Lithium-sulfur batteries are considered to be a new generation of high energy density batteries due to their non-toxicity,low cost and high theoretical specific capacity.However,the development of practical lithium-su...Lithium-sulfur batteries are considered to be a new generation of high energy density batteries due to their non-toxicity,low cost and high theoretical specific capacity.However,the development of practical lithium-sulfur batteries is seriously impeded by the sluggish multi-electron redox reaction of sulfur species and obstinate shuttle effect of polysulfides.In this study,a porous lanthanum oxychloride(LaOCl)nanofiber is designed as adsorbent and electrocatalyst of polysulfides to regulate the redox kinetics and suppress shuttling of sulfur species.Benefiting from the porous architecture and luxuriant active site of LaOCl nanofibers,the meliorative polarization effect and sulfur expansion can be accomplished.The LaOCl/S electrode exhibits an initial discharge specific capacity of 1112.3 mAh/g at 0.1 C and maintains a superior cycling performance with a slight decay of 0.02%per cycle over 1000 cycles at 1.0 C.Furthermore,even under a high sulfur loading of 4.6mg/cm^(2),the S cathode with LaOCl nanofibers still retains a high reversible areal capacity of 4.2 mAh/cm^(2)at 0.2 C and a stable cycling performance.Such a porous host expands the application of rare earth based catalysts in lithium-sulfur batteries and provides an alternative approach to facilitate the polysulfides conversion kinetics.展开更多
Density functional theory(DFT)was performed to systematically study the adsorption and dissociation of N_(2)on Ir(100)and Ir(110)surfaces.By analyzing the properties,including adsorption energies,reaction barriers,and...Density functional theory(DFT)was performed to systematically study the adsorption and dissociation of N_(2)on Ir(100)and Ir(110)surfaces.By analyzing the properties,including adsorption energies,reaction barriers,and optimal adsorption sites,the hollow(H)sites were finally identified as favorable dissociation sites for N_(2).The dissociation barriers of N_(2)are 0.87eV on Ir(100)and 1.12eV on Ir(110),which can be overcome at around 348 and 448 K,respectively.Therefore,Ir(100)is screened as a promising catalyst for N_(2)dissociation compared to Ir(110).This can be attributed to the significantly higher adsorption energy of N_(2)on the H site of Ir(100)(−0.48 eV)compared to that on Ir(110)(−0.22 eV),leading to different dissociation mechanisms on Ir(100)and Ir(110).Ir(100)can dissociate N_(2)directly on H site and Ir(110)should firstly capture N_(2)via bridge site and further transfer the adsorbed N_(2)to the H site,which will dramatically deteriorate the reactivity of N_(2)dissociation.In addition,the following protonation processes of dissociated∗N atoms are all exothermal at 348 K on Ir(100),indicating that the ammonia synthesis can occur spontaneously as the temperature higher than 348 K.These results have provided a reasonable materials design scheme for subsequent ammonia synthesis.展开更多
In order to reduce the greenhouse effect caused by the rapid increase of CO_(2)concentration in the atmosphere,it is necessary to develop more efficient,controllable,and highly sensitive adsorbing materials.In this st...In order to reduce the greenhouse effect caused by the rapid increase of CO_(2)concentration in the atmosphere,it is necessary to develop more efficient,controllable,and highly sensitive adsorbing materials.In this study,the adsorption behavior of CO_(2)on BC_(3)nanosheets under an external electric field was explored based on density functional theory(DFT).It was found that CO_(2)experienced a transition from physisorption to chemisorption in the electric field range of 0.0060-0.0065 a.u..In addition,the adsorption/desorption of CO_(2)is reversible and can be precisely controlled by switching on/off at the electric field of 0.0065 a.u..The selective adsorption of CO_(2)/H_(2)/CH_(4)by BC_(3)can also be used to realize gas separation and purification under different electric fields.This study highlighted the potential application of BC_(3)nanosheets as a high-performance,controllable material for CO_(2)capture,regeneration,and separation in an electric field.展开更多
In this paper,a novel BC_(3)N_(2)monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations.The predicted structure mee...In this paper,a novel BC_(3)N_(2)monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations.The predicted structure meets the thermodynamical,dynamical,and mechanical stability requirements.Interestingly,the BC_(3)N_(2)plane shows a metallic character.Importantly,BC_(3)N_(2)has an in-plane stiffness comparable to that of graphene.We have also investigated the adsorption characteristics of CO_(2)on pristine monolayer and Mo functionalized monolayer using density functional theory.Subsequently,electronic structures of the interacting systems(CO_(2)molecule and substrates)have been preliminarily explored.The results show that Mo/BC_(3)N_(2)has a stronger adsorption capacity towards CO_(2)comparing with the pristine one,which can provide a reference for the further study of the CO_(2)reduction mechanism on the transition metal-functionalized surface as well as the new catalyst’s design.展开更多
As the greenhouse effect concerns increases,the development of new materials for the efficient capture and separation of CO_(2)gas from gas mixtures has become a matter of urgency.In this study,we performed density fu...As the greenhouse effect concerns increases,the development of new materials for the efficient capture and separation of CO_(2)gas from gas mixtures has become a matter of urgency.In this study,we performed density functional theory(DFT)calculations to investigate the adsorption and separation behavior of CO_(2)/CH_(4)/H_(2)on the surface of two-dimensional(2D)Al_(2)C materials under positive/negative applied electric fields.In the absence of an electric field CO_(2)is weakly physisorbed on the Al_(2)C surface,but with the application of an applied electric field,the adsorption state of CO_(2)gradually changes from physical to chemisorption(adsorption energy changes from-0.29 e V to-3.61 e V),while the negative electric field has little effect on the adsorption of CO_(2).We conclude that the C=O bond in adsorbed CO_(2)can be activated under an external electric field(maximum activation of 15%under an external electric field of 0-0.005 a.u.).Only in the presence of an applied electric field of 0.0033 a.u.and temperatures above525 K/675 K can the adsorption/separation reaction of CO_(2)single adsorption and CO_(2)/CH_(4)/H_(2)mixture be spontaneous.The adsorption/desorption of CO_(2)on Al_(2)C nanosheet in an electric field of 0.003-0.0033 a.u.is all exothermic,which can be easily controlled by switching on/off the electric field without any energy barriers.The capacity of Al_(2)C to capture CO_(2)per unit electric field decreases with increasing CO_(2)concentration,but still has efficient gas separation properties for CO_(2)/CH_(4)/H_(2).Our theoretical results could provide guidance for designing high-capacity and high-selectivity CO_(2)capture materials.展开更多
Using particle swarm optimization(PSO)methodology for crystal structure prediction,we predicted a novel two-dimensional(2 D)monolayer of silicide diphosphorus compound:SiP_(2),which exhibits good stability as examined...Using particle swarm optimization(PSO)methodology for crystal structure prediction,we predicted a novel two-dimensional(2 D)monolayer of silicide diphosphorus compound:SiP_(2),which exhibits good stability as examined via cohesive energy,mechanical criteria,molecular dynamics simulation and all positive phonon spectrum,respectively.The SiP_(2)monolayer is an indirect semiconductor with the band gap as 1.8484 eV(PBE)or 2.681 eV(HSE06),which makes it more advantageous for high-frequencyresponse optoelectronic materials.Moreover,the monolayer is a relatively hard auxetic material with negative Possion’s ratios,and also possesses a ultrahigh carrier mobility(1.069×10^(5)cm^(2)V^(-1)s^(-1))which is approximately four times the maximum value in phosphorene and comparable to the value of graphene and CP monolayers.Furthermore,the effects of strains on band structures and optical properties of SiP_(2)monolayer have been studied,as well as CO_(2)molecules can be strongly chemically adsorbed on the SiP_(2)monolayer.A semiconductor-to-metal transition for-9.5%strain ratio case and a huge optical absorption capacity on the order of 10^(6)cm^(-1)in visible region present.These theoretical findings endow SiP_(2)Monolayer to be a novel 2 D material holding great promises for applications in highperformance electronics,optoelectronics,mechanics and CO_(2)capturing material.展开更多
Constructing 3 D multifunctional conductive framework as stable sulfur cathode contributes to develop advanced lithium-sulfur(Li-S)batteries.Herein,a freestanding electrode with nickel foam framework and nitrogen dope...Constructing 3 D multifunctional conductive framework as stable sulfur cathode contributes to develop advanced lithium-sulfur(Li-S)batteries.Herein,a freestanding electrode with nickel foam framework and nitrogen doped porous carbon(PC)network is presented to encapsulate active sulfur for Li-S batteries.In such a mutually embedded architecture with high stability,the interconnected carbon network and nickel foam matrix can expedite ionic/electro nic tra nsport and sustain volume variations of sulfur.Furthermore,rationally designed porous structures provide sufficient internal space and large surface area for high active sulfur loading and polar polysulfides anchoring.Benefiting from the synergistic superiority,the Ni/PC-S cathode exhibits a high initial capacity of around 1200 mAh/g at 0.2 C,excelle nt rate perfo rmance,and high cycling stability with a low decay rate of 0.059%per cycle after 500 cycles.This work provides a useful strategy to exploit freestanding porous framework for diverse applications.展开更多
To reduce the greenhouse effect caused by the surgery of nitrogen-oxides concentration in the atmosphere and develop a future energy carrier of renewables,it is very critical to develop more efficient,controllable,and...To reduce the greenhouse effect caused by the surgery of nitrogen-oxides concentration in the atmosphere and develop a future energy carrier of renewables,it is very critical to develop more efficient,controllable,and highly sensitive catalytic materials.In our work,we proposed that nitric oxide(NO),as a supplement to N_(2) for the synthesis of ammonia,which is equipped with a lower barrier.And the study highlighted the potential of CeO_(2)(111)nanosheets with La doping and oxygen vacancy(OV)as a high-performance,controllable material for NO capture at the site of Vo site,and separation the process of hydrogenation.We also reported that the E_(ads) of-1.12 eV with horizontal adsorption and the Bader charge of N increasing of 0.53|e|and O increasing of 0.17|e|at the most active site of reduction-OV predicted.It is worth noting thatΔG of NORR(NO reduction reaction)shows good performance(thermodynamically spontaneous reaction)to synthesize ammonia and water at room temperature in the theoretical calculation.展开更多
Nitric oxide reduction to ammonia by electrocatalysis is the potential application in the elimination of smog and energy conversion. In this work, the feasibility of the application of two-dimensional metal borides(MB...Nitric oxide reduction to ammonia by electrocatalysis is the potential application in the elimination of smog and energy conversion. In this work, the feasibility of the application of two-dimensional metal borides(MBenes) in nitric oxide electroreduction reaction(NOER) was investigated through density functional theory calculations. Including the geometry and electronic structure of five kinds of MBenes, the adsorption of NO on the surface of these substrates, the selective adsorption of hydrogen protons during the hydrogenation process, and the overpotential in the electrocatalytic ammonia synthesis process. As a result, Mn B exhibited the most favorable catalytic performance according to the associative pathways,which is thermodynamically performed spontaneously, and WB has a minimum overpotential of 0.37 V vs. RHE in the process of ammonia production according to the dissociative pathway. Overall, our work is the first to explore the electrocatalytic NO through the dissociative mechanism to synthesize ammonia in-depth and proves that MBenes are efficient NO electrocatalytic ammonia synthesis catalysts. These research results provide a new direction for the development of electrocatalytic ammonia synthesis experimentally and theoretically.展开更多
Using the global particle-swarm optimization method and density functional theory,we predict a new stable two-dimensional layered material:MgSiP_(2)with a low-buckled honeycomb lattice.Our HSE06 calculation shows that...Using the global particle-swarm optimization method and density functional theory,we predict a new stable two-dimensional layered material:MgSiP_(2)with a low-buckled honeycomb lattice.Our HSE06 calculation shows that MgSiP_(2)is an indirect-gap semiconductor with a band-gap of 1.20 eV,closed to that of bulk silicon.More remarkably,MgSiP_(2)exhibits worthwhile anisotropy along with electron and hole carrier mobility.A ultrahigh electron mobility is even up to 1.29×10^(4)cm^(2)V^(-1)s^(-1).while the hole mobility is nearly zero along the a direction.The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP_(2)may be a good candidate for solar cell or photochemical catalysis material.Furthermore,we explore MgSiP_(2)as an anode for sodium-ion batte ries.Upon Na adsorption,the semiconducting MgSiP_(2)transforms to a metallic state,ensuring good electrical conductivity.A maximum theoretical capacity of 1406 mAh/g,a small volume change(within 9.5%),a small diffusion barrier(~0.16 eV)and low average open-circuit voltages(~0.15 V)were found fo r MgSiP_(2)as an anode for sodium-ion batteries.These results are helpful to deepen the understanding of MgSiP_(2)as a nanoelectronic device and a potential anode for Na-ion batteries.展开更多
In this paper,the process of ammonia borane(AB)hydrolysis generate H_(2) on the transition metal Fe@Co core-shell structure has been obtained.According to the different roles played by H_(2)O molecules and the number ...In this paper,the process of ammonia borane(AB)hydrolysis generate H_(2) on the transition metal Fe@Co core-shell structure has been obtained.According to the different roles played by H_(2)O molecules and the number of H_(2)O molecules involved,there are three schemes of reaction paths.RouteⅠdoes not involve the dissociation of H_(2)O molecules and all H atoms come from AB.Moreover,the H_(2)O molecule has no effect on the breaking of the B—H bond or the N—H bond.The reaction absorbs more heat during the formation of the second and third H_(2) molecules.RouteⅡincludes the dissociation of H_(2)O molecules and the cleavage of B—H or N—H bonds,respectively,and the reaction shows a slight exotherm.RouteⅢstarted from the break of the B—N bond and obtained 3H_(2) molecules through the participation of different numbers of H_(2)O molecules.After multiple comparative analyses,the optimal hydrolysis reaction path has been obtained,and the reaction process can proceed spontaneously at room temperature.展开更多
Ammonia borane(NHsBH3,AB)is an ideal raw material of hydrogen production with higher hydrogen storage capacity.In this paper,the catalytic processes of AB dehydrogenation were described from different ways,including t...Ammonia borane(NHsBH3,AB)is an ideal raw material of hydrogen production with higher hydrogen storage capacity.In this paper,the catalytic processes of AB dehydrogenation were described from different ways,including thermal dehydrogenation,hydrolysis,methanolysis,photocatalysis and photopiezoelectric synergy catalysis with experimental research and theoretical calculations.Catalyst models include bulk materials,two-dimensional materials,nanocluster particles and single/diatomic structures.Among them,the proportion of H2 released is different,and the reaction conditions are also different,which are suitable for different application scenarios.Through this review,we could have a preliminary comprehensive understanding of AB dehydrogenation reaction.展开更多
In the present work,a stable two-dimensional(2D)P_(2)Si monolayer was predicted.The monolayer is semimetallic/metallic under the PBE/HSE06 functional and is mechanically isotropic.The stability of the P_(2)Si monolaye...In the present work,a stable two-dimensional(2D)P_(2)Si monolayer was predicted.The monolayer is semimetallic/metallic under the PBE/HSE06 functional and is mechanically isotropic.The stability of the P_(2)Si monolayer has been proved via cohesive energy,mechanical criteria,molecular dynamics simulation,and phonon dispersion respectively,and the monolayer possesses high carrier mobility which is three times that of Mo S_(2).On the other hand,the catalytic performance of the P_(2)Si monolayer modified with a single transition metals(M=Sc-Cu)atom for the electrochemical reduction of CO_(2)was investigated,and the monolayer can catalyze CO_(2)with three constraints:stable molecular dynamics,high migration potential of metal atoms,and suitable band gap for electrocatalyst after metal doping exhibiting excellent catalytic stabilization activity and CRR selectivity.In addition,the reduction product of V@P_(2)Si is HCOOH with an overpotential as low as 0.75 V,and the most suitable reaction path is^(*)CO_(2)→^(*)CHOO→O^(*)CHOH→^(*)+HCOOH with the final reduction product HCOOH obtained.As a whole,the above results endow the P_(2)Si monolayer to be a good 2D material holding great promises for applications in nanoelectronics and CO_(2)reduction catalysts.展开更多
We predicted two stable two-dimensional materials of carbon and bismuth elements,namely BiC and Bi_(2)C monolayers.The stabilities of two monolayers were examined by cohesive energy,Born criteria,first-principle MD si...We predicted two stable two-dimensional materials of carbon and bismuth elements,namely BiC and Bi_(2)C monolayers.The stabilities of two monolayers were examined by cohesive energy,Born criteria,first-principle MD simulations and phonon spectra,respectively.By including the spin-orbit coupling effects,the BiC monolayer is a metal and the Bi_(2)C monolayer possesses a narrow direct(indirect)band gap of 0.403(0.126)eV under the HSE06(GGA-PBE)functional.For the adsorption of CO_(2)molecules,the BiC and Bi_(2)C monolayers have three stable adsorption sites C2,T3 and T4 with the adsorption energies as-0.57,-0.51 and-0.81 eV,and the activation ability on the adsorption as T4>T3>C2.These consequences make the BiC and Bi_(2)C monolayers to be promising adsorbents to capture CO_(2)gas,the Bi_(2)C monolayer to be well photovoltaics and optoelectronics material,and the BiC monolayer to be ideal battery and electronics materials,respectively.展开更多
In this paper,Fe_(36)Co_(44)nanocluster structure is used to catalyze the hydrolysis reaction of ammonia borane to produce H_(2).Firstly,we complete the construction of Fe_(36)Co_(44)cluster structure and calculate th...In this paper,Fe_(36)Co_(44)nanocluster structure is used to catalyze the hydrolysis reaction of ammonia borane to produce H_(2).Firstly,we complete the construction of Fe_(36)Co_(44)cluster structure and calculate the electronic properties of the cluster.By comparing the adsorption process of Ammonia Borane (AB) in active sites of the cluster,which have different Effective Coordination Number (ECN),the qualitative relationship between ECN and the catalytic activation of AB is clarified,and the optimal catalytic active site is obtained.Then,from the perspective of different reaction paths,we study the hydrolysis reaction of AB in multiple paths,and obtain 5 different reaction paths and energy profiles.The calculation results show that in the case of N–H bond priority break (path 5),the reaction has the minimum rate-determining step (RDS) barrier (about 1.02 e V) and the entire reaction is exothermic (about 0.40 e V).So,path 5 is an optimal catalytic reaction path.This study will have an important guiding significance for the study of the AB hydrolysis reaction mechanism.展开更多
Nitrogen reduction reactions(NRR) under room conditions remain the challenge for N_(2)activation on metal-based catalysis materials. Herein, the M-doped CeO_(2)(111)(M = Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) with ...Nitrogen reduction reactions(NRR) under room conditions remain the challenge for N_(2)activation on metal-based catalysis materials. Herein, the M-doped CeO_(2)(111)(M = Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) with oxygen vacancies, are systematically investigated by spin-polarized DFT + U calculations.We discuss briefly the situation of OVs on pure and reduced cerium, and we found that(1) doping TMs can promote the formation of oxygen defects, apart from Ti and V-dopant,(2) the O atoms are easier to escape connecting to M atoms than the ones of adjacent atoms connecting to the Ce(111), the value of OVs formation energies decrease as the TMs radius decrease. Also, our computational results show that Cr-doped, Mn-doped, Fe-doped, and Co-doped CeO_(2)(111) adsorbs N;strongly than the stoichiometric surface and other M-doped CeO_(2)surfaces with adsorption energies of-0.82,-1.02,-0.83 and-1.05 e V.Through COHP analysis, it is found that the predicted active sites have good catalytic performance.展开更多
The heightened piezoelectric performance observed in most explored perovskite systems is typically at-tributed to the electric-field-induced phase transition near the morphotropic phase boundary(MPB)or polymorphic pha...The heightened piezoelectric performance observed in most explored perovskite systems is typically at-tributed to the electric-field-induced phase transition near the morphotropic phase boundary(MPB)or polymorphic phase boundary(PPB).This study,however,unveils a distinct piezoelectric enhancement mechanism in the xPb(Nb_(2/3)Ni_(1/3))O_(3)-(1-x)Pb(Zr_(0.3)Ti_(0.7))O_(3)(PNN-PZT)system,diverging from the MPB/PPB-centered piezoelectric systems.Notably,the composition with x=0.55,positioned close to the tetragonal-pseudocubic(T-PC)phase boundary,achieves an unprecedented piezoelectric coefficient(d_(33))of 1264 pC/N,while retaining a tetragonal local structure.Importantly,on a local scale,electric fields do not in-cite phase transitions,suggesting that the exceptional piezoelectric performance in PNN-PZT stems from polarization extension near the T-PC boundary.Distinct from other mechanisms,the relative permittivity significantly increases post-poling due to this particular enhancement process.The dielectric behavior in poled specimens does not exhibit a conspicuous change at the ferroelectric-relaxor transition tempera-ture.However,both the relative permittivity and planar electromechanical coupling coefficient experience a sharp rise in the temperature range of−25℃to 25℃.This investigation underscores the pivotal role of designing compositionally-driven T-PC phase boundaries,presenting a promising avenue for enhancing piezoelectric properties in ferroelectric ceramics.展开更多
Electrocatalytic synthesis of ammonia as an environment-friendly and sustainable development method has received widespread attention in recent years.Two-dimensional(2D)materials are a promising catalyst for ammonia s...Electrocatalytic synthesis of ammonia as an environment-friendly and sustainable development method has received widespread attention in recent years.Two-dimensional(2D)materials are a promising catalyst for ammonia synthesis due to their large surface area.In this work,we have constructed a series of 2D metal borides(MBenes)with transition metal(TM)defects(TMd-MBenes)and comprehensively calculated the reactivity of electrocatalytic synthesis of ammonia-based on density functional theory.The results have demonstrated that the TMd-MBenes can effectively activate nitrogen oxide(NO)and nitrogen(N2)molecules thermodynamically.Particularly interesting,the co-chemisorption of O atoms,dissociated from NO,can facilitate the spilled of the inert N2 molecules into single N atoms,which can further hydrogenate into ammonia easily with an ultralow limiting potential of 0.59 V on TMd-MnB.Our research has not only provided clues for catalyst design for experimental study but also paved the way for the industrial application of electrocatalytic ammonia synthesis.展开更多
Synthesis of ammonia gas through environmental protection and low-cost electrocatalysis is one of the ways to solve the current human energy problems.Herein,through the study of density functional theory(DFT),a series...Synthesis of ammonia gas through environmental protection and low-cost electrocatalysis is one of the ways to solve the current human energy problems.Herein,through the study of density functional theory(DFT),a series of transition metal single atoms are embedded in the defect-containing h-BN to construct a TM@B_(2) N_(2)(TM=Ti-Zn,Nb-Ag) two-dimensional nanostructure.The activation effect of these single-atom catalysts on NO molecules and the electrochemical performance of catalyzing NO reduction reaction(NORR)were explored.All reaction pathways are studied in detail,and competition between hydrogen proton and ammonia(NH3) oxidation with NORRs is also explored.Among the16 transition metal atoms we studied,the intercalation of Pb atom into h-BN has the best catalytic activity.The reaction rate-limiting potential of NORR is only 0.55 eV,and the surface HER reaction and ammonia oxidation can be effectively inhibited.It is hoped that our research can further promote the application of h-BN in the field of catalysis and provide some guidance for experimental workers in the field of ammonia synthesis.展开更多
The photocatalytic nitrogen reduction reaction(NRR) has mild reaction conditions and only requires sunlight energy as a driving force to replace the traditional ammonia synthesis method. We herein investigate the cata...The photocatalytic nitrogen reduction reaction(NRR) has mild reaction conditions and only requires sunlight energy as a driving force to replace the traditional ammonia synthesis method. We herein investigate the catalytic activity and selectivity on Penta-B_(2)C for NRR by using density functional theory calculations. Penta-B_(2)C is a semiconductor with an indirect bandgap(2.328 e V) and is kinetically stable based on molecular dynamic simulations. The optical absorption spectrum of Penta-B;C is achieved in the ultraviolet and visible range. Effective light absorption is more conducive to generate photo-excited electrons and improving photocatalytic performances. Rich B atoms as activation sites in Penta-B_(2)C facilitate capturing N_(2). The activated N_(2)molecule prefers the side-on adsorption configuration on Penta-B_(2)C, which facilitates the subsequent reduction reaction. Among considered NRR mechanisms on Penta-B_(2)C, the best pathway prefers the enzymatic mechanism, only required a low onset potential of 0.23 V. The hydrogen evolution reaction is inhibited when the hydrogen adsorption concentration is increased or N_(2)molecules first occupy the adsorption sites. Our results indicate Penta-B_(2)C is a highly reactive and selective photocatalyst for NRR. Our work provides theoretical insights into the experiments and has guiding significance to synthesize efficient NRR photocatalysts.展开更多
基金supported by the Scientific Research Program Funded by Education Department of Shaanxi Provincial Government(No.22JK0411)the Natural Science Basic Research Program of Shaanxi Province(No.2023-JC-QN-0165)the National Natural Science Foundation of China(No.21603109).
文摘Lithium-sulfur batteries are considered to be a new generation of high energy density batteries due to their non-toxicity,low cost and high theoretical specific capacity.However,the development of practical lithium-sulfur batteries is seriously impeded by the sluggish multi-electron redox reaction of sulfur species and obstinate shuttle effect of polysulfides.In this study,a porous lanthanum oxychloride(LaOCl)nanofiber is designed as adsorbent and electrocatalyst of polysulfides to regulate the redox kinetics and suppress shuttling of sulfur species.Benefiting from the porous architecture and luxuriant active site of LaOCl nanofibers,the meliorative polarization effect and sulfur expansion can be accomplished.The LaOCl/S electrode exhibits an initial discharge specific capacity of 1112.3 mAh/g at 0.1 C and maintains a superior cycling performance with a slight decay of 0.02%per cycle over 1000 cycles at 1.0 C.Furthermore,even under a high sulfur loading of 4.6mg/cm^(2),the S cathode with LaOCl nanofibers still retains a high reversible areal capacity of 4.2 mAh/cm^(2)at 0.2 C and a stable cycling performance.Such a porous host expands the application of rare earth based catalysts in lithium-sulfur batteries and provides an alternative approach to facilitate the polysulfides conversion kinetics.
基金funded by the Natural Science Foundation of China(No.21603109)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)supported by Natural Science Basic Research Program of Shanxi(Nos.2022JQ-108,2022JQ096)。
文摘Density functional theory(DFT)was performed to systematically study the adsorption and dissociation of N_(2)on Ir(100)and Ir(110)surfaces.By analyzing the properties,including adsorption energies,reaction barriers,and optimal adsorption sites,the hollow(H)sites were finally identified as favorable dissociation sites for N_(2).The dissociation barriers of N_(2)are 0.87eV on Ir(100)and 1.12eV on Ir(110),which can be overcome at around 348 and 448 K,respectively.Therefore,Ir(100)is screened as a promising catalyst for N_(2)dissociation compared to Ir(110).This can be attributed to the significantly higher adsorption energy of N_(2)on the H site of Ir(100)(−0.48 eV)compared to that on Ir(110)(−0.22 eV),leading to different dissociation mechanisms on Ir(100)and Ir(110).Ir(100)can dissociate N_(2)directly on H site and Ir(110)should firstly capture N_(2)via bridge site and further transfer the adsorbed N_(2)to the H site,which will dramatically deteriorate the reactivity of N_(2)dissociation.In addition,the following protonation processes of dissociated∗N atoms are all exothermal at 348 K on Ir(100),indicating that the ammonia synthesis can occur spontaneously as the temperature higher than 348 K.These results have provided a reasonable materials design scheme for subsequent ammonia synthesis.
基金funded by the National Natural Science Foundation of China(No.21603109)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)。
文摘In order to reduce the greenhouse effect caused by the rapid increase of CO_(2)concentration in the atmosphere,it is necessary to develop more efficient,controllable,and highly sensitive adsorbing materials.In this study,the adsorption behavior of CO_(2)on BC_(3)nanosheets under an external electric field was explored based on density functional theory(DFT).It was found that CO_(2)experienced a transition from physisorption to chemisorption in the electric field range of 0.0060-0.0065 a.u..In addition,the adsorption/desorption of CO_(2)is reversible and can be precisely controlled by switching on/off at the electric field of 0.0065 a.u..The selective adsorption of CO_(2)/H_(2)/CH_(4)by BC_(3)can also be used to realize gas separation and purification under different electric fields.This study highlighted the potential application of BC_(3)nanosheets as a high-performance,controllable material for CO_(2)capture,regeneration,and separation in an electric field.
基金supported by the National Natural Science Foundation of China(Nos.21603109,U1404216,U1904179,U1404608)the Special Fund of Tianshui Normal University,China(Grant No.CXJ2020-08)+1 种基金the Key Science Fund of Educational Department of Henan Province of China(Nos.19A140013,20B140010)Shaanxi Provincial Education Department Serves Local Scientific Research Program(Nos.19JC020,20JK0676)。
文摘In this paper,a novel BC_(3)N_(2)monolayer has been found with a graphene-like structure using the developed particle swarm optimization algorithm in combination with ab initio calculations.The predicted structure meets the thermodynamical,dynamical,and mechanical stability requirements.Interestingly,the BC_(3)N_(2)plane shows a metallic character.Importantly,BC_(3)N_(2)has an in-plane stiffness comparable to that of graphene.We have also investigated the adsorption characteristics of CO_(2)on pristine monolayer and Mo functionalized monolayer using density functional theory.Subsequently,electronic structures of the interacting systems(CO_(2)molecule and substrates)have been preliminarily explored.The results show that Mo/BC_(3)N_(2)has a stronger adsorption capacity towards CO_(2)comparing with the pristine one,which can provide a reference for the further study of the CO_(2)reduction mechanism on the transition metal-functionalized surface as well as the new catalyst’s design.
基金funded by the National Natural Science Foundation of China(No.21603109)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)。
文摘As the greenhouse effect concerns increases,the development of new materials for the efficient capture and separation of CO_(2)gas from gas mixtures has become a matter of urgency.In this study,we performed density functional theory(DFT)calculations to investigate the adsorption and separation behavior of CO_(2)/CH_(4)/H_(2)on the surface of two-dimensional(2D)Al_(2)C materials under positive/negative applied electric fields.In the absence of an electric field CO_(2)is weakly physisorbed on the Al_(2)C surface,but with the application of an applied electric field,the adsorption state of CO_(2)gradually changes from physical to chemisorption(adsorption energy changes from-0.29 e V to-3.61 e V),while the negative electric field has little effect on the adsorption of CO_(2).We conclude that the C=O bond in adsorbed CO_(2)can be activated under an external electric field(maximum activation of 15%under an external electric field of 0-0.005 a.u.).Only in the presence of an applied electric field of 0.0033 a.u.and temperatures above525 K/675 K can the adsorption/separation reaction of CO_(2)single adsorption and CO_(2)/CH_(4)/H_(2)mixture be spontaneous.The adsorption/desorption of CO_(2)on Al_(2)C nanosheet in an electric field of 0.003-0.0033 a.u.is all exothermic,which can be easily controlled by switching on/off the electric field without any energy barriers.The capacity of Al_(2)C to capture CO_(2)per unit electric field decreases with increasing CO_(2)concentration,but still has efficient gas separation properties for CO_(2)/CH_(4)/H_(2).Our theoretical results could provide guidance for designing high-capacity and high-selectivity CO_(2)capture materials.
基金funded by the Scientific Research Fund of Hunan Provincial Education Department of China(No.16A081)the Natural Science Foundation of China(Nos.21603109,11304128)+2 种基金the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)the Science and Technology Program of Henan Department of Science and Technology,China(No.182102310609)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering(Mathematics,Electronic Science and Technology)。
文摘Using particle swarm optimization(PSO)methodology for crystal structure prediction,we predicted a novel two-dimensional(2 D)monolayer of silicide diphosphorus compound:SiP_(2),which exhibits good stability as examined via cohesive energy,mechanical criteria,molecular dynamics simulation and all positive phonon spectrum,respectively.The SiP_(2)monolayer is an indirect semiconductor with the band gap as 1.8484 eV(PBE)or 2.681 eV(HSE06),which makes it more advantageous for high-frequencyresponse optoelectronic materials.Moreover,the monolayer is a relatively hard auxetic material with negative Possion’s ratios,and also possesses a ultrahigh carrier mobility(1.069×10^(5)cm^(2)V^(-1)s^(-1))which is approximately four times the maximum value in phosphorene and comparable to the value of graphene and CP monolayers.Furthermore,the effects of strains on band structures and optical properties of SiP_(2)monolayer have been studied,as well as CO_(2)molecules can be strongly chemically adsorbed on the SiP_(2)monolayer.A semiconductor-to-metal transition for-9.5%strain ratio case and a huge optical absorption capacity on the order of 10^(6)cm^(-1)in visible region present.These theoretical findings endow SiP_(2)Monolayer to be a novel 2 D material holding great promises for applications in highperformance electronics,optoelectronics,mechanics and CO_(2)capturing material.
基金financially supported by the National Natural Science Foundation of China(No.21603109)the Henan Joint Fund of theNational Natural Science Foundation of China(No.U1404216)。
文摘Constructing 3 D multifunctional conductive framework as stable sulfur cathode contributes to develop advanced lithium-sulfur(Li-S)batteries.Herein,a freestanding electrode with nickel foam framework and nitrogen doped porous carbon(PC)network is presented to encapsulate active sulfur for Li-S batteries.In such a mutually embedded architecture with high stability,the interconnected carbon network and nickel foam matrix can expedite ionic/electro nic tra nsport and sustain volume variations of sulfur.Furthermore,rationally designed porous structures provide sufficient internal space and large surface area for high active sulfur loading and polar polysulfides anchoring.Benefiting from the synergistic superiority,the Ni/PC-S cathode exhibits a high initial capacity of around 1200 mAh/g at 0.2 C,excelle nt rate perfo rmance,and high cycling stability with a low decay rate of 0.059%per cycle after 500 cycles.This work provides a useful strategy to exploit freestanding porous framework for diverse applications.
基金funded by the Natural Science Foundation of China(No.21603109)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)the Special Fund of Tianshui Normal University,China(No.CXJ2020-08)。
文摘To reduce the greenhouse effect caused by the surgery of nitrogen-oxides concentration in the atmosphere and develop a future energy carrier of renewables,it is very critical to develop more efficient,controllable,and highly sensitive catalytic materials.In our work,we proposed that nitric oxide(NO),as a supplement to N_(2) for the synthesis of ammonia,which is equipped with a lower barrier.And the study highlighted the potential of CeO_(2)(111)nanosheets with La doping and oxygen vacancy(OV)as a high-performance,controllable material for NO capture at the site of Vo site,and separation the process of hydrogenation.We also reported that the E_(ads) of-1.12 eV with horizontal adsorption and the Bader charge of N increasing of 0.53|e|and O increasing of 0.17|e|at the most active site of reduction-OV predicted.It is worth noting thatΔG of NORR(NO reduction reaction)shows good performance(thermodynamically spontaneous reaction)to synthesize ammonia and water at room temperature in the theoretical calculation.
基金funded by the Natural Science Foundation of China (No.21603109)the Henan Joint Fund of the National Natural Science Foundation of China (No.U1404216)+1 种基金the Special Fund of Tianshui Normal University,China (No.CXJ2020-08)the Scientific Research Program Funded by Shaanxi Provincial Education Department (No.20JK0676)。
文摘Nitric oxide reduction to ammonia by electrocatalysis is the potential application in the elimination of smog and energy conversion. In this work, the feasibility of the application of two-dimensional metal borides(MBenes) in nitric oxide electroreduction reaction(NOER) was investigated through density functional theory calculations. Including the geometry and electronic structure of five kinds of MBenes, the adsorption of NO on the surface of these substrates, the selective adsorption of hydrogen protons during the hydrogenation process, and the overpotential in the electrocatalytic ammonia synthesis process. As a result, Mn B exhibited the most favorable catalytic performance according to the associative pathways,which is thermodynamically performed spontaneously, and WB has a minimum overpotential of 0.37 V vs. RHE in the process of ammonia production according to the dissociative pathway. Overall, our work is the first to explore the electrocatalytic NO through the dissociative mechanism to synthesize ammonia in-depth and proves that MBenes are efficient NO electrocatalytic ammonia synthesis catalysts. These research results provide a new direction for the development of electrocatalytic ammonia synthesis experimentally and theoretically.
基金supported by Henan Joint Funds of the National Natural Science Foundation of China(Nos.U1904179,U1404608 and U1404216)the National Natural Science Foundation of China(No.21603109)the Key Science Fund of Educational Department of Henan Province of China(No.20B140010)。
文摘Using the global particle-swarm optimization method and density functional theory,we predict a new stable two-dimensional layered material:MgSiP_(2)with a low-buckled honeycomb lattice.Our HSE06 calculation shows that MgSiP_(2)is an indirect-gap semiconductor with a band-gap of 1.20 eV,closed to that of bulk silicon.More remarkably,MgSiP_(2)exhibits worthwhile anisotropy along with electron and hole carrier mobility.A ultrahigh electron mobility is even up to 1.29×10^(4)cm^(2)V^(-1)s^(-1).while the hole mobility is nearly zero along the a direction.The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP_(2)may be a good candidate for solar cell or photochemical catalysis material.Furthermore,we explore MgSiP_(2)as an anode for sodium-ion batte ries.Upon Na adsorption,the semiconducting MgSiP_(2)transforms to a metallic state,ensuring good electrical conductivity.A maximum theoretical capacity of 1406 mAh/g,a small volume change(within 9.5%),a small diffusion barrier(~0.16 eV)and low average open-circuit voltages(~0.15 V)were found fo r MgSiP_(2)as an anode for sodium-ion batteries.These results are helpful to deepen the understanding of MgSiP_(2)as a nanoelectronic device and a potential anode for Na-ion batteries.
基金funded by the Natural Science Foundation of China(Nos.21603109,U1404216)the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)。
文摘In this paper,the process of ammonia borane(AB)hydrolysis generate H_(2) on the transition metal Fe@Co core-shell structure has been obtained.According to the different roles played by H_(2)O molecules and the number of H_(2)O molecules involved,there are three schemes of reaction paths.RouteⅠdoes not involve the dissociation of H_(2)O molecules and all H atoms come from AB.Moreover,the H_(2)O molecule has no effect on the breaking of the B—H bond or the N—H bond.The reaction absorbs more heat during the formation of the second and third H_(2) molecules.RouteⅡincludes the dissociation of H_(2)O molecules and the cleavage of B—H or N—H bonds,respectively,and the reaction shows a slight exotherm.RouteⅢstarted from the break of the B—N bond and obtained 3H_(2) molecules through the participation of different numbers of H_(2)O molecules.After multiple comparative analyses,the optimal hydrolysis reaction path has been obtained,and the reaction process can proceed spontaneously at room temperature.
基金funded by the Natural Science Basic Research Program of Shaanxi(Nos.2022JQ-108 and 2022JQ-096)the National Natural Science Foundation of China(No.22104079).
文摘Ammonia borane(NHsBH3,AB)is an ideal raw material of hydrogen production with higher hydrogen storage capacity.In this paper,the catalytic processes of AB dehydrogenation were described from different ways,including thermal dehydrogenation,hydrolysis,methanolysis,photocatalysis and photopiezoelectric synergy catalysis with experimental research and theoretical calculations.Catalyst models include bulk materials,two-dimensional materials,nanocluster particles and single/diatomic structures.Among them,the proportion of H2 released is different,and the reaction conditions are also different,which are suitable for different application scenarios.Through this review,we could have a preliminary comprehensive understanding of AB dehydrogenation reaction.
基金funded by the Natural Science Foundation of China(Nos.21603109,11304128)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)+1 种基金the Science and Technology Program of Henan Department of Science and Technology,China(No.182102310609)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering(Mathematics,Education and Electronic Science and Technology)。
文摘In the present work,a stable two-dimensional(2D)P_(2)Si monolayer was predicted.The monolayer is semimetallic/metallic under the PBE/HSE06 functional and is mechanically isotropic.The stability of the P_(2)Si monolayer has been proved via cohesive energy,mechanical criteria,molecular dynamics simulation,and phonon dispersion respectively,and the monolayer possesses high carrier mobility which is three times that of Mo S_(2).On the other hand,the catalytic performance of the P_(2)Si monolayer modified with a single transition metals(M=Sc-Cu)atom for the electrochemical reduction of CO_(2)was investigated,and the monolayer can catalyze CO_(2)with three constraints:stable molecular dynamics,high migration potential of metal atoms,and suitable band gap for electrocatalyst after metal doping exhibiting excellent catalytic stabilization activity and CRR selectivity.In addition,the reduction product of V@P_(2)Si is HCOOH with an overpotential as low as 0.75 V,and the most suitable reaction path is^(*)CO_(2)→^(*)CHOO→O^(*)CHOH→^(*)+HCOOH with the final reduction product HCOOH obtained.As a whole,the above results endow the P_(2)Si monolayer to be a good 2D material holding great promises for applications in nanoelectronics and CO_(2)reduction catalysts.
基金funded by the Natural Science Foundation of China(Nos.21603109,11304128)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)+1 种基金the Science and Technology Program of Henan Department of Science and Technology,China(No.182102310609)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering(Mathematics,Education and Electronic Science and Technology).
文摘We predicted two stable two-dimensional materials of carbon and bismuth elements,namely BiC and Bi_(2)C monolayers.The stabilities of two monolayers were examined by cohesive energy,Born criteria,first-principle MD simulations and phonon spectra,respectively.By including the spin-orbit coupling effects,the BiC monolayer is a metal and the Bi_(2)C monolayer possesses a narrow direct(indirect)band gap of 0.403(0.126)eV under the HSE06(GGA-PBE)functional.For the adsorption of CO_(2)molecules,the BiC and Bi_(2)C monolayers have three stable adsorption sites C2,T3 and T4 with the adsorption energies as-0.57,-0.51 and-0.81 eV,and the activation ability on the adsorption as T4>T3>C2.These consequences make the BiC and Bi_(2)C monolayers to be promising adsorbents to capture CO_(2)gas,the Bi_(2)C monolayer to be well photovoltaics and optoelectronics material,and the BiC monolayer to be ideal battery and electronics materials,respectively.
基金funded by the Scientific Research Program Funded by Shaanxi Provincial Education Department (No. 20JK0676)the National Supercomputing Center in Zhengzhoupartially supported by the postgraduate research opportunities program of HZWTECH (No. HZWTECH-PROP)。
文摘In this paper,Fe_(36)Co_(44)nanocluster structure is used to catalyze the hydrolysis reaction of ammonia borane to produce H_(2).Firstly,we complete the construction of Fe_(36)Co_(44)cluster structure and calculate the electronic properties of the cluster.By comparing the adsorption process of Ammonia Borane (AB) in active sites of the cluster,which have different Effective Coordination Number (ECN),the qualitative relationship between ECN and the catalytic activation of AB is clarified,and the optimal catalytic active site is obtained.Then,from the perspective of different reaction paths,we study the hydrolysis reaction of AB in multiple paths,and obtain 5 different reaction paths and energy profiles.The calculation results show that in the case of N–H bond priority break (path 5),the reaction has the minimum rate-determining step (RDS) barrier (about 1.02 e V) and the entire reaction is exothermic (about 0.40 e V).So,path 5 is an optimal catalytic reaction path.This study will have an important guiding significance for the study of the AB hydrolysis reaction mechanism.
基金funded by the Natural Science Foundation of China (Nos. 21603109, 21772152)the Henan Joint Fund of the National Natural Science Foundation of China (No. U1404216)+3 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department (No. 20JK0676)the Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi (No. 2020CG032)the Cultivation Plan of Young Scientific Researchers in Higher Education Institutions of Shanxi Provincethe Fund for Shanxi “1331 Project”。
文摘Nitrogen reduction reactions(NRR) under room conditions remain the challenge for N_(2)activation on metal-based catalysis materials. Herein, the M-doped CeO_(2)(111)(M = Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) with oxygen vacancies, are systematically investigated by spin-polarized DFT + U calculations.We discuss briefly the situation of OVs on pure and reduced cerium, and we found that(1) doping TMs can promote the formation of oxygen defects, apart from Ti and V-dopant,(2) the O atoms are easier to escape connecting to M atoms than the ones of adjacent atoms connecting to the Ce(111), the value of OVs formation energies decrease as the TMs radius decrease. Also, our computational results show that Cr-doped, Mn-doped, Fe-doped, and Co-doped CeO_(2)(111) adsorbs N;strongly than the stoichiometric surface and other M-doped CeO_(2)surfaces with adsorption energies of-0.82,-1.02,-0.83 and-1.05 e V.Through COHP analysis, it is found that the predicted active sites have good catalytic performance.
基金financially supported by the National Natu-ral Science Foundation of China(Project No.11704301)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2022JM212).
文摘The heightened piezoelectric performance observed in most explored perovskite systems is typically at-tributed to the electric-field-induced phase transition near the morphotropic phase boundary(MPB)or polymorphic phase boundary(PPB).This study,however,unveils a distinct piezoelectric enhancement mechanism in the xPb(Nb_(2/3)Ni_(1/3))O_(3)-(1-x)Pb(Zr_(0.3)Ti_(0.7))O_(3)(PNN-PZT)system,diverging from the MPB/PPB-centered piezoelectric systems.Notably,the composition with x=0.55,positioned close to the tetragonal-pseudocubic(T-PC)phase boundary,achieves an unprecedented piezoelectric coefficient(d_(33))of 1264 pC/N,while retaining a tetragonal local structure.Importantly,on a local scale,electric fields do not in-cite phase transitions,suggesting that the exceptional piezoelectric performance in PNN-PZT stems from polarization extension near the T-PC boundary.Distinct from other mechanisms,the relative permittivity significantly increases post-poling due to this particular enhancement process.The dielectric behavior in poled specimens does not exhibit a conspicuous change at the ferroelectric-relaxor transition tempera-ture.However,both the relative permittivity and planar electromechanical coupling coefficient experience a sharp rise in the temperature range of−25℃to 25℃.This investigation underscores the pivotal role of designing compositionally-driven T-PC phase boundaries,presenting a promising avenue for enhancing piezoelectric properties in ferroelectric ceramics.
基金funded by the Natural Science Foundation of China(No.21603109)the Henan Joint Fund of the National Natural Science Foundation of China(No.U1404216)+2 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department(No.20JK0676)the Science and Technology Innovation Talents in Universities of Henan Province(No.22HASTIT028)supported by Natural Science Basic Research Program of Shanxi(Nos.2022JQ-108,2022JQ-096).
文摘Electrocatalytic synthesis of ammonia as an environment-friendly and sustainable development method has received widespread attention in recent years.Two-dimensional(2D)materials are a promising catalyst for ammonia synthesis due to their large surface area.In this work,we have constructed a series of 2D metal borides(MBenes)with transition metal(TM)defects(TMd-MBenes)and comprehensively calculated the reactivity of electrocatalytic synthesis of ammonia-based on density functional theory.The results have demonstrated that the TMd-MBenes can effectively activate nitrogen oxide(NO)and nitrogen(N2)molecules thermodynamically.Particularly interesting,the co-chemisorption of O atoms,dissociated from NO,can facilitate the spilled of the inert N2 molecules into single N atoms,which can further hydrogenate into ammonia easily with an ultralow limiting potential of 0.59 V on TMd-MnB.Our research has not only provided clues for catalyst design for experimental study but also paved the way for the industrial application of electrocatalytic ammonia synthesis.
基金financially supported by the Natural Science Foundation of China (No.21603109)Henan Joint Fund of the National Natural Science Foundation of China (No. U1404216)the Scientific Research Program Funded by Shaanxi Provincial Education Department (No.20JK0676)。
文摘Synthesis of ammonia gas through environmental protection and low-cost electrocatalysis is one of the ways to solve the current human energy problems.Herein,through the study of density functional theory(DFT),a series of transition metal single atoms are embedded in the defect-containing h-BN to construct a TM@B_(2) N_(2)(TM=Ti-Zn,Nb-Ag) two-dimensional nanostructure.The activation effect of these single-atom catalysts on NO molecules and the electrochemical performance of catalyzing NO reduction reaction(NORR)were explored.All reaction pathways are studied in detail,and competition between hydrogen proton and ammonia(NH3) oxidation with NORRs is also explored.Among the16 transition metal atoms we studied,the intercalation of Pb atom into h-BN has the best catalytic activity.The reaction rate-limiting potential of NORR is only 0.55 eV,and the surface HER reaction and ammonia oxidation can be effectively inhibited.It is hoped that our research can further promote the application of h-BN in the field of catalysis and provide some guidance for experimental workers in the field of ammonia synthesis.
基金funded by the Natural Science Foundation of China (No. 21603109)the Henan Joint Fund of the National Natural Science Foundation of China (No. U1404216)the Scientific Research Program Funded by Shaanxi Provincial Education Department (No. 20JK0676)。
文摘The photocatalytic nitrogen reduction reaction(NRR) has mild reaction conditions and only requires sunlight energy as a driving force to replace the traditional ammonia synthesis method. We herein investigate the catalytic activity and selectivity on Penta-B_(2)C for NRR by using density functional theory calculations. Penta-B_(2)C is a semiconductor with an indirect bandgap(2.328 e V) and is kinetically stable based on molecular dynamic simulations. The optical absorption spectrum of Penta-B;C is achieved in the ultraviolet and visible range. Effective light absorption is more conducive to generate photo-excited electrons and improving photocatalytic performances. Rich B atoms as activation sites in Penta-B_(2)C facilitate capturing N_(2). The activated N_(2)molecule prefers the side-on adsorption configuration on Penta-B_(2)C, which facilitates the subsequent reduction reaction. Among considered NRR mechanisms on Penta-B_(2)C, the best pathway prefers the enzymatic mechanism, only required a low onset potential of 0.23 V. The hydrogen evolution reaction is inhibited when the hydrogen adsorption concentration is increased or N_(2)molecules first occupy the adsorption sites. Our results indicate Penta-B_(2)C is a highly reactive and selective photocatalyst for NRR. Our work provides theoretical insights into the experiments and has guiding significance to synthesize efficient NRR photocatalysts.
