Metal‐organic frameworks(MOFs)are a series of highly porous crystalline materials,which are built from inorganic metal nodes and organic linkers through coordination bonds.Their unique porous structural features(such...Metal‐organic frameworks(MOFs)are a series of highly porous crystalline materials,which are built from inorganic metal nodes and organic linkers through coordination bonds.Their unique porous structural features(such as high porosity,high surface areas,and highly ordered nanoporous structures)and designable structures and compositions have facilitated their use in gas capture,separation,catalysis,and energy storage and conversion.Recently,the design and synthesis of pure MOFs and their derivatives have opened new routes to develop highly efficient electrocatalysts toward oxygen reduction reactions(ORR)and oxygen evolution reactions(OER),which are the core electrode reactions in many energy storage and conversion techniques,such as metal‐air batteries and fuel cells.This review first discusses recent progress in the synthesis and the electrocatalytic applications of pure MOF‐based electrocatalysts toward ORR or OER,including pure MOFs,MOFs decorated with active species,and MOFs incorporated with conductive materials.The following section focuses on the advancements of the design and preparation of various MOF‐derived materials-such as inorganic nano‐(or micro‐)structures/porous carbon composites,pure porous carbons,pure inorganic nano‐(or micro‐)structured materials,and single‐atom electrocatalysts-and their applications in oxygen electrocatalysis.Finally,we present a conclusion and an outlook for some general design strategies and future research directions of MOF‐based oxygen electrocatalysts.展开更多
Pd/TiO2 catalysts prepared by three different methods(impregnation,deposition-precipitation,and polyethylene glycol reduction)were investigated in the selective catalytic reduction of NOx by H2(H2-SCR).It was found th...Pd/TiO2 catalysts prepared by three different methods(impregnation,deposition-precipitation,and polyethylene glycol reduction)were investigated in the selective catalytic reduction of NOx by H2(H2-SCR).It was found that the preparation method exerted a significant effect on the activity of the Pd/TiO2 catalyst,and that the catalyst prepared by the polyethylene glycol reduction method exhibited the highest activity in the reduction of NOx.Characterization of the catalyst showed that,in the Pd/TiO2 catalyst prepared by the polyethylene glycol reduction method,the existing Pd species was Pd0,which is the desirable species for the H2-SCR of NOx.In situ DRIFTS studies demonstrated that over this catalyst,more chelating nitrite and monodentate nitrite species formed,both of which are reactive intermediates in the H2-SCR of NOx.All of these factors account for the high activity of Pd/TiO2 prepared by the polyethylene glycol reduction method.展开更多
Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical...Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical reaction of CaC_(2) and a carbonate(CaCO_(3),Na2CO_(3),or NaHCO_(3))at ambient temperature.The resultant OACMs are micro mesoporous carbon nanomaterials with high specific area(>648 m2 g^(-1)),highly crosslinked texture,and rich alkynyl and oxygenated groups.The OACMs exhibit excellent Hg(Ⅱ)adsorption due to the soft acid-soft base interaction between alkynyl and Hg(Ⅱ),and OACM-3 derived from CaC_(2) and NaHCO_(3) has the saturated Hg(Ⅱ)adsorbance of 483.9 mg g^(-1)along with good selectivity and recyclability.The adsorption is mainly chemisorption following the Langmuir mode.OACM-3 also shows high adsorbance for other heavy metal ions,e.g.256.6 mg g^(-1)for Pb(II),232.4 mg g^(-1)for Zn(II),and 198.7 mg g^(-1)for Cu(II).This work expands the mechnochemical reaction of CaC_(2)with carbonates and possibly other oxyanionic salts,provides a new synthesis approach for functional alkynyl carbon materials with excellent adsorption performance for heavy metal ions,as well as a feasible approach for CO2 resource utilization.展开更多
In this work,the solubility data and liquid-phase mass transfer coefficients of hydrogen(H2),methane(CH4)and their mixtures in vacuum gas oil(VGO)at temperatures(353.15-453.15 K)and pressures(1-7 MPa)were measured,whi...In this work,the solubility data and liquid-phase mass transfer coefficients of hydrogen(H2),methane(CH4)and their mixtures in vacuum gas oil(VGO)at temperatures(353.15-453.15 K)and pressures(1-7 MPa)were measured,which are necessary for catalytic cracking process simulation and design.The solubility of H2 and CH4 in VGO increases with the increase of pressure,but decreases with the increase of temperature.Henry’s constants of H2 and CH4 follow the relation of In H=-413.05/T+5.27 and In H=-990.67/T+5.87,respectively.The molar fractions of H2 and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients.The results showed that with the increase of pressure,the liquid-phase mass transfer coefficients increase.Furthermore,the solubility of H2 and CH4 in VGO was predicted by the predictive COSMO-RS model,and the predicted values agree well with experimental data.In addition,the gas-liquid equilibrium(GLE)for H2+CH4+VGO system at different feeding gas ratios in volume fraction(i.e.,H285%+CH415%and H290%+CH410%)was measured.The selectivity of H2 to CH4 predicted by the COSMO-RS model agrees well with experimental data.This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.展开更多
Our recent theoretical studies have screened out CuCs-doped Ag-based promising catalysts for ethylene epoxidation[ACS Catal.11,3371(2021)].The theoretical results were based on surface modeling,while in the actual rea...Our recent theoretical studies have screened out CuCs-doped Ag-based promising catalysts for ethylene epoxidation[ACS Catal.11,3371(2021)].The theoretical results were based on surface modeling,while in the actual reaction process Ag catalysts are particle shaped.In this work,we combine density functional theory(DFT),Wulff construction theory,and micro kinetic analysis to study the catalytic performance of Ag catalysts at the particle model.It demonstrates that the CuCs-doped Ag catalysts are superior to pure Ag catalysts in terms of selectivity and activity,which is further proved by experimental validation.The characterization analysis finds that both Cu and Cs dopant promote particle growth as well as particle dispersion,resulting in a grain boundary-rich Ag particle.Besides,CuCs also facilitate electrophilic atomic oxygen formation on catalyst surface,which is benefitial for ethylene oxide formation and desorption.Our work provides a case study for catalyst design by combining theory and experiment.展开更多
In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan(HMF) from fructose in aqueous solution is systemically investigated by perfo...In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan(HMF) from fructose in aqueous solution is systemically investigated by performing CFD simulations.Influential factors including solvents,residence time distribution of reaction mixtures,heat transfer conditions and micro-channel configurations are evaluated in terms of the reaction performance indices,i.e.,conversion of fructose,HMF selectivity and yield.A scale-up method from a single channel to a multiple channel reactor is also proposed.It is demonstrated that:1) at the single channel scale,controlling residence times and temperature distribution of the reaction mixture within the channel is crucial for enhancing the reaction performance,while different channel configurations lead to marginal improvements;2) for the scaling-up of the reaction process,a reactor module containing 15 circular parallel channels could be used as module blocks,which can be stacked one by one to meet the required reactor performance and production capacity.The present results show that micro-reactors are quite suitable for HMF production.展开更多
Thermocatalytic CO_(2) hydrogenation with"green"H_(2) is one of the most promising carbon-negative technologies,wherein oxygen vacancy engineering serves as a novel strategy to boost the catalytic performanc...Thermocatalytic CO_(2) hydrogenation with"green"H_(2) is one of the most promising carbon-negative technologies,wherein oxygen vacancy engineering serves as a novel strategy to boost the catalytic performance of oxide-containing catalysts.To provide theoretical guidance and promote technical progress in this important field,the status and prospect of oxygen vacancy-boosted thermocatalytic CO_(2) hydrogenation have been thoroughly reviewed herein.Specifically,fundamentals including origin,construction,characterization,and function of oxygen vacancies will be systematically summarized and oxygen vacancy-boosted hydrogenation reactions including methanation,reverse water-gas shift(RWGS),methanol synthesis,and other hydrogenation processes will be comprehensively introduced.In addition,challenges and opportunities from the perspective of engineering strategies,promoting effects,and mediating mechanisms of oxygen vacancies will be succinctly proposed.Overall,this review is expected to gain more insights into the role of oxygen vacancies and shed new light on the design of efficient oxide-containing catalysts.展开更多
Four kinds of cryptomelane-type octahedral molecular sieve(OMS)-2-X(the X represents the molar ratio of KMnO4/MnAc2) were prepared as catalytic materials for ozone decomposition through a one-step hydrothermal reactio...Four kinds of cryptomelane-type octahedral molecular sieve(OMS)-2-X(the X represents the molar ratio of KMnO4/MnAc2) were prepared as catalytic materials for ozone decomposition through a one-step hydrothermal reaction of KMnO4 and MnAc2, by changing their molar ratios. These samples were characterized by N2 adsorption–desorption, X-ray di raction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), temperature programmed reduction by H2(H2-TPR) and X-ray photoelectron spectroscopy(XPS). Among them, the OMS-2-0.7 sample showed the best O3 conversion of 92% under high relative humidity(RH) of 90% and gas hourly space velocity of 585,000 h-1. This was accordingly thought as a possible way for purifying ozone-containing waste gases under high RH atmospheres. The e ciency of ozone decomposition of the prepared OMS-2-X sample was found to be related to specific surface area, particle size, surface oxygen vacancies, and Mn3+ cation amounts. The one-step hydrothermal synthesis was shown to be a simple method to prepare the considerably active OMS-2 solids for ozone decomposition.展开更多
Nanosheet(S) and nanoplate(P) γ-Al_2O_3 were synthesized by simple hydrothermal methods and employed as supports for Ni catalysts in CO_2 methanation.Both of the nanostructured Ni/Al_2O_3 catalysts displayed good act...Nanosheet(S) and nanoplate(P) γ-Al_2O_3 were synthesized by simple hydrothermal methods and employed as supports for Ni catalysts in CO_2 methanation.Both of the nanostructured Ni/Al_2O_3 catalysts displayed good activity.In comparison,the Ni/Al_2O_3-S catalyst showed higher CO_2 conversion than the Ni/Al_2O_3-P counterpart at the reaction temperature ranging from 250 to 400 °C.The physical and chemical properties of the catalysts were systematically characterized by N2 sorption,X-ray diffraction(XRD),high resolution-transmission electron microscopy(HR-TEM),hydrogen temperature-programmed reduction(H2-TPR) and CO_2 temperature-programmed desorption(CO_2-TPD) techniques.Higher specific surface area and stronger metal-support interactions were confirmed on the Ni/Al_2O_3-S catalyst,which may lead to smaller particle size of Ni nanoparticles.Moreover,the Ni/Al_2O_3-S catalyst possessed more abundant weak and medium basic sites,which would benefit the activation of CO_2.The smaller Ni size and more suitable basic sites may rationalize the superior activity of the Ni/Al_2O_3-S catalyst.Besides,the Ni/Al_2O_3-S catalyst exhibited excellent stability at 325 °C for 40 h.展开更多
Design and preparation of novel advanced carbon materials with unique architecture and functional groups is of great significance.Herein,a spongy acetylenic carbon material(SACM) was prepared through mechanochemical r...Design and preparation of novel advanced carbon materials with unique architecture and functional groups is of great significance.Herein,a spongy acetylenic carbon material(SACM) was prepared through mechanochemical reaction of CaC2 and chlorinated rubber in a planetary ball mill at ambient temperature.Its composition and structure were characterized,and its electrochemical properties and adsorption performance for Hg^2+ were studied.The SACM is composed of submicron spongy aggregates with high carbon content(81.8%) and specific area(503.9 m^2·g^-1),rich porosity and acetylenic groups.The SACM exhibits excellent adsorption for Hg2+with saturated adsorption amount being 157.1 mg·g^-1,which is superior to conventional carbon materials.Further,it exhibits good electrochemical performance with low equivalent series resistance(0.50 Ω),excellent cycling stability and ideal double layer capacitive behavior.This paper provides a novel and universal synthesis method of spongy carbon materials,and better results can be expected through tuning the pore structure,graphitization degree,and heteroatoms of the target carbon materials.展开更多
The ordered membrane electrode assembly(MEA)has gained much attention because of its potential in improving mass transfer.Here,a comprehensive study was conducted on the influence of the patterned microporous layer(MP...The ordered membrane electrode assembly(MEA)has gained much attention because of its potential in improving mass transfer.Here,a comprehensive study was conducted on the influence of the patterned microporous layer(MPL)on the proton exchange membrane fuel cell performances.When patterned MPL is employed,grooves are generated between the catalyst layer and the gas diffusion layer.It is found that the grooves do not increase the contact resistance,and it is beneficial for water retention.When the MEA works under low humidity scenarios,the MEA with patterned MPL illustrated higher performance,due to the reduced inner resistance caused by improved water retention,leading to increased ionic conductivity.However,when the humidity is higher than 80%or working under high current density,the generated water accumulated in the grooves and hindered the oxygen mass transport,leading to a reduced MEA performance.展开更多
O3 decomposition catalysts with excellent performance still need to be developed. In this study, Ag-modified manganese oxides(AgMnOx) were synthesized by a simple co-precipitation method. The effect of calcination tem...O3 decomposition catalysts with excellent performance still need to be developed. In this study, Ag-modified manganese oxides(AgMnOx) were synthesized by a simple co-precipitation method. The effect of calcination temperature on the activity of MnOx and AgMnOxcatalysts was investigated. The effect of the amount of Ag addition on the activity and structure of the catalysts was further studied by activity testing and characterization by a variety of techniques. The activity of 8%AgMnOxfor ozone decomposition was significantly enhanced due to the formation of the Ag1.8 Mn8 O16 structure, indicating that this phase has excellent performance for ozone decomposition.The weight content of Ag1.8 Mn8 O16 in the 8%AgMnOxcatalyst was only about 33.76%, which further indicates the excellent performance of the Ag1.8 Mn8 O16 phase for ozone decomposition. The H2 temperature programmed reduction(H2-TPR) results indicated that the reducibility of the catalysts increased due to the formation of the Ag1.8 Mn8 O16 structure.This study provides guidance for a follow-up study on Ag-modified manganese oxide catalysts for ozone decomposition.展开更多
Doped phosphide is promising in earthabundant element based catalysts for hydrogen evolution reaction(HER). Here we employ ammonium hypophosphite(NH4H2PO2) to synthesize a novel parallel doped catalyst,nitrogen doped ...Doped phosphide is promising in earthabundant element based catalysts for hydrogen evolution reaction(HER). Here we employ ammonium hypophosphite(NH4H2PO2) to synthesize a novel parallel doped catalyst,nitrogen doped molybdenum phosphide nanoparticles(NPs)supported on nitrogen doped carbon nanotubes(N-MoP/N-CNTs). The NH4H2PO2 as a bifunctional agent severs as both phosphidation agent and nitrogen source, which makes the synthetic route simple and efficient. The as-obtained parallel doped N-MoP/N-CNTs show an overpotential of 103±5 mV at 10 mA cm-2, which is 140 mV lower than that of MoP NPs. The enhanced HER performance is attributed to the electronic effect by doped MoP and CNTs supports. This work provides a facile route to synthesize doped phosphides for the potential applications in hydrogen energy.展开更多
Manganese oxides supported by ZSM-5 zeolite(Mn/ZSM-5) as well as their further modified by Ce promoter were achieved by simple impregnation method for ozone catalytic decomposition. The yCe20Mn/ZSM-5–81 catalyst with...Manganese oxides supported by ZSM-5 zeolite(Mn/ZSM-5) as well as their further modified by Ce promoter were achieved by simple impregnation method for ozone catalytic decomposition. The yCe20Mn/ZSM-5–81 catalyst with 8% Ce loading showed the highest catalytic activity at relative humidity of 50% and a space velocity of 360 L/(g × hr), giving 93% conversion of 600 ppm O_(3) after 5 hr. Moreover, this sample still maintained highly activity and stability in humid air with 50%–70% relative humidity. Series of physicochemical characterization including X-ray diffraction, temperature-programmed technology(NH_3-TPD and H_(2)-TPR), X-ray photoelectron spectroscopy and oxygen isotopic exchange were introduced to disclose the structure-performance relationship. The results indicated that moderate Si/Al ratio(81) of zeolite support was beneficial for ozone decomposition owing to the synergies of acidity and hydrophobicity. Furthermore, compared with 20 Mn/ZSM-5-81, Ce doping could enhance the amount of low valance manganese(such as Mn^(2+) and Mn^(3+)). Besides, the Ce^(3+)/Ce^(4+) ratio of 8Ce20Mn/ZSM-5-81 sample was higher than that of 4Ce_(2)0 Mn/ZSM-5-81. Additionally, the synergy between the MnO_x and CeO_(2) could easily transfer electron via the redox cycle, thus resulting in an increased reducibility at low temperatures and high concentration of surface oxygen. This study provides important insights to the utilization of porous zeolite with high surface area to disperse active component of manganese for ozone decomposition.展开更多
Pt catalysts with nitrogen-doped graphene oxide (GO) as support and CeO_(2)as promoter were prepared by impregnation method,and their catalytic oxidation of formaldehyde (HCHO) at room temperature was tested.The Pt-Ce...Pt catalysts with nitrogen-doped graphene oxide (GO) as support and CeO_(2)as promoter were prepared by impregnation method,and their catalytic oxidation of formaldehyde (HCHO) at room temperature was tested.The Pt-CeO_(2)/N-rGO (reduced GO) with a mass fraction of 0.7% Pt and 0.8%CeO_(2)exhibited an excellent catalytic performance with the 100% conversion of HCHO at room temperature.Physicochemical characterization demonstrated that nitrogendoping greatly increased the defect degree and the specific surface area of GO,enhanced the dispersion of Pt and promoted more zero-valent Pt.The synergistic effect between CeO_(2)and Pt was also beneficial to the dispersion of Pt.Nitrogen-doping promoted the production of more Ce3+ions,generating more oxygen vacancies,which was conducive to O_(2)adsorption.As a result,the catalyst exhibited enhanced redox properties,leading to the best catalytic activity.Finally,an attempt to propose the reaction mechanism of HCHO oxidation has been made.展开更多
Red mud,as a solid waste produced during the alumina production,can cause severe ecoenvironmental pollution and health risks to human.Therefore,the resourcing of this type of solid waste is an effective way for the su...Red mud,as a solid waste produced during the alumina production,can cause severe ecoenvironmental pollution and health risks to human.Therefore,the resourcing of this type of solid waste is an effective way for the sustainable development.This paper reviews the recent progress on red mud-based catalysts for the removal of typical air pollutants,such as the catalytic reduction of nitrogen oxides(NO_(x))by NH_(3)(NH_(3)-SCR)and the catalytic oxidation of CO and volatile organic compounds(VOCs).The factors influencing the catalytic performance and the structure–activity relationship have been discussed.Future prospects and directions for the development of such catalysts are also proposed.This review would benefit for the high value-added utilizations of red mud in mitigating atmospheric pollutions.展开更多
An environmentally benign WO_(3) wrapped cubic CeO_(2) core-shell catalyst(Ce@W)was developed for the selective catalytic reduction of NO_(x) with NH_(3).Compared with CeW particles prepared via the conventional co-pr...An environmentally benign WO_(3) wrapped cubic CeO_(2) core-shell catalyst(Ce@W)was developed for the selective catalytic reduction of NO_(x) with NH_(3).Compared with CeW particles prepared via the conventional co-precipitation method,this core-shell catalyst not only displays higher tolerance to SO_(2) and H_(2)O,but also exhibits a wider activity tempe rature window of 250-450℃,in which NO_(x)conversion and N_(2) selectivity reaches 100%.The improved performance of Ce@W catalysts can be contributed to the strong interactions between CeO_(2)(100) and WO_(3),which generates more Ce^(3+) and surface chemisorbed oxygen.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)reveal that the more thermally stable Br?nsted acid sites on Ce@W lead to its excellent high-temperature activity.展开更多
Electrochemical coupling hydrogen evolution with biomass reforming reaction(named electrochemical hydrogen and chemical cogeneration(EHCC)),which realizes green hydrogen production and chemical upgrading simultaneousl...Electrochemical coupling hydrogen evolution with biomass reforming reaction(named electrochemical hydrogen and chemical cogeneration(EHCC)),which realizes green hydrogen production and chemical upgrading simultaneously,is a promising method to build a carbon-neutral society.Herein,we analyze the EHCC process by considering the market assessment.The ethanol to acetic acid and hydrogen approach is the most feasible for large-scale hydrogen production.We develop AuCu nanocatalysts,which can selectively oxidize ethanol to acetic acid(>97%)with high long-term activity.The isotopic and in-situ infrared experiments reveal that the promoted water dissociation step by alloying contributes to the enhanced activity of the partial oxidation reaction path.A flow-cell electrolyzer equipped with the AuCu anodic catalyst achieves the steady production of hydrogen and acetic acid simultaneously in both high selectivity(>90%),demonstrating the potential scalable application for green hydrogen production with low energy consumption and high profitability.展开更多
Water electrolysis is considered to be an effective way to fabricate hydrogen, and it is desirable to find the highly efficient, inexpensive and good durability bifunctional electrocatalysts for overall water splittin...Water electrolysis is considered to be an effective way to fabricate hydrogen, and it is desirable to find the highly efficient, inexpensive and good durability bifunctional electrocatalysts for overall water splitting.In this paper, we synthesis a unique structured catalyst that was composed by Co_9S_8 nanowires and nickel cobalt layered double hydroxide(NiCo-LDH) nanosheets. The ultrathin nanosheets decorated on the Co_9S_8 nanoarrays offer large specific surface area, numerous active edge sites and excellent electrical conductivity for fast electron transfer. Benefiting from this heterogeneous structure, the catalyst presents excellent catalytic performance in alkaline media. It requires 168 mV to reach current density of 10 mA/cm^2 for HER and 278 m V to reach current density of 30 mA/cm^2 for OER. When used as electrode in a homemade two-electrode system, it only needs t a voltage of 1.63 V to achieve current densities of 10 mA/cm^2, which proves Co_9S_8@NiCo LDH/NF as a superior bifunctional catalyst for water splitting.展开更多
It is urgent to develop low-cost but efficient oxygen reduction reaction(ORR)catalysts for the emerging clean energy devices of fuel cells based on proton exchange membrane.Herein,we report a facile method to covert t...It is urgent to develop low-cost but efficient oxygen reduction reaction(ORR)catalysts for the emerging clean energy devices of fuel cells based on proton exchange membrane.Herein,we report a facile method to covert the biomass of black fungus into an efficient ORR catalyst.The black fungus undergoes hydrothermal and pyrolysis processes to transform into carbon-based materials.The as-obtained BF-N-950 catalyst shows prominent ORR catalytic activities in both acidic and alkaline electrolytes with a half-wave potential reaching 0.77 and 0.91 V,respectively.A membrane electrolyte assembly was fabricated with the as-obtained BF-N-950 as the cathode catalyst which shows a high peak power density of255 mW cm^-2.The study shows the potential of converting conventional biomass into low-cost ORR catalyst,which is promising for the fuel cell technology.展开更多
文摘Metal‐organic frameworks(MOFs)are a series of highly porous crystalline materials,which are built from inorganic metal nodes and organic linkers through coordination bonds.Their unique porous structural features(such as high porosity,high surface areas,and highly ordered nanoporous structures)and designable structures and compositions have facilitated their use in gas capture,separation,catalysis,and energy storage and conversion.Recently,the design and synthesis of pure MOFs and their derivatives have opened new routes to develop highly efficient electrocatalysts toward oxygen reduction reactions(ORR)and oxygen evolution reactions(OER),which are the core electrode reactions in many energy storage and conversion techniques,such as metal‐air batteries and fuel cells.This review first discusses recent progress in the synthesis and the electrocatalytic applications of pure MOF‐based electrocatalysts toward ORR or OER,including pure MOFs,MOFs decorated with active species,and MOFs incorporated with conductive materials.The following section focuses on the advancements of the design and preparation of various MOF‐derived materials-such as inorganic nano‐(or micro‐)structures/porous carbon composites,pure porous carbons,pure inorganic nano‐(or micro‐)structured materials,and single‐atom electrocatalysts-and their applications in oxygen electrocatalysis.Finally,we present a conclusion and an outlook for some general design strategies and future research directions of MOF‐based oxygen electrocatalysts.
基金supported by the National Key R&D Program of China(2017YFC0210700)the National Natural Science Foundation of China(21876009,21611130170)+1 种基金the Beijing Municipal Natural Science Foundation(8162030)the Fundamental Research Funds for the Central Universities(XK1802-1)~~
文摘Pd/TiO2 catalysts prepared by three different methods(impregnation,deposition-precipitation,and polyethylene glycol reduction)were investigated in the selective catalytic reduction of NOx by H2(H2-SCR).It was found that the preparation method exerted a significant effect on the activity of the Pd/TiO2 catalyst,and that the catalyst prepared by the polyethylene glycol reduction method exhibited the highest activity in the reduction of NOx.Characterization of the catalyst showed that,in the Pd/TiO2 catalyst prepared by the polyethylene glycol reduction method,the existing Pd species was Pd0,which is the desirable species for the H2-SCR of NOx.In situ DRIFTS studies demonstrated that over this catalyst,more chelating nitrite and monodentate nitrite species formed,both of which are reactive intermediates in the H2-SCR of NOx.All of these factors account for the high activity of Pd/TiO2 prepared by the polyethylene glycol reduction method.
基金supports from the National Natural Science Foundation of China(No.21776015)the University Scientific Research Project of Anhui Province(No.KJ2018A0065&KJ2020A0245).
文摘Adsorptive removal of heavy metal ions from wastewater is very important,and the key is the development of efficient sorbents.In this work,oxygenated alkynyl carbon materials(OACMs)were synthesized via mechanochemical reaction of CaC_(2) and a carbonate(CaCO_(3),Na2CO_(3),or NaHCO_(3))at ambient temperature.The resultant OACMs are micro mesoporous carbon nanomaterials with high specific area(>648 m2 g^(-1)),highly crosslinked texture,and rich alkynyl and oxygenated groups.The OACMs exhibit excellent Hg(Ⅱ)adsorption due to the soft acid-soft base interaction between alkynyl and Hg(Ⅱ),and OACM-3 derived from CaC_(2) and NaHCO_(3) has the saturated Hg(Ⅱ)adsorbance of 483.9 mg g^(-1)along with good selectivity and recyclability.The adsorption is mainly chemisorption following the Langmuir mode.OACM-3 also shows high adsorbance for other heavy metal ions,e.g.256.6 mg g^(-1)for Pb(II),232.4 mg g^(-1)for Zn(II),and 198.7 mg g^(-1)for Cu(II).This work expands the mechnochemical reaction of CaC_(2)with carbonates and possibly other oxyanionic salts,provides a new synthesis approach for functional alkynyl carbon materials with excellent adsorption performance for heavy metal ions,as well as a feasible approach for CO2 resource utilization.
基金Supported by the National Natural Science Foundation of China(U1862103).
文摘In this work,the solubility data and liquid-phase mass transfer coefficients of hydrogen(H2),methane(CH4)and their mixtures in vacuum gas oil(VGO)at temperatures(353.15-453.15 K)and pressures(1-7 MPa)were measured,which are necessary for catalytic cracking process simulation and design.The solubility of H2 and CH4 in VGO increases with the increase of pressure,but decreases with the increase of temperature.Henry’s constants of H2 and CH4 follow the relation of In H=-413.05/T+5.27 and In H=-990.67/T+5.87,respectively.The molar fractions of H2 and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients.The results showed that with the increase of pressure,the liquid-phase mass transfer coefficients increase.Furthermore,the solubility of H2 and CH4 in VGO was predicted by the predictive COSMO-RS model,and the predicted values agree well with experimental data.In addition,the gas-liquid equilibrium(GLE)for H2+CH4+VGO system at different feeding gas ratios in volume fraction(i.e.,H285%+CH415%and H290%+CH410%)was measured.The selectivity of H2 to CH4 predicted by the COSMO-RS model agrees well with experimental data.This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.
基金This work is supported by PetroChina Innovation Foundation(2019D-5007-0403).
文摘Our recent theoretical studies have screened out CuCs-doped Ag-based promising catalysts for ethylene epoxidation[ACS Catal.11,3371(2021)].The theoretical results were based on surface modeling,while in the actual reaction process Ag catalysts are particle shaped.In this work,we combine density functional theory(DFT),Wulff construction theory,and micro kinetic analysis to study the catalytic performance of Ag catalysts at the particle model.It demonstrates that the CuCs-doped Ag catalysts are superior to pure Ag catalysts in terms of selectivity and activity,which is further proved by experimental validation.The characterization analysis finds that both Cu and Cs dopant promote particle growth as well as particle dispersion,resulting in a grain boundary-rich Ag particle.Besides,CuCs also facilitate electrophilic atomic oxygen formation on catalyst surface,which is benefitial for ethylene oxide formation and desorption.Our work provides a case study for catalyst design by combining theory and experiment.
文摘In this work the applicability of the micro-channel reactor technique to the production of promising platform chemical 5-hydroxymethyl furan(HMF) from fructose in aqueous solution is systemically investigated by performing CFD simulations.Influential factors including solvents,residence time distribution of reaction mixtures,heat transfer conditions and micro-channel configurations are evaluated in terms of the reaction performance indices,i.e.,conversion of fructose,HMF selectivity and yield.A scale-up method from a single channel to a multiple channel reactor is also proposed.It is demonstrated that:1) at the single channel scale,controlling residence times and temperature distribution of the reaction mixture within the channel is crucial for enhancing the reaction performance,while different channel configurations lead to marginal improvements;2) for the scaling-up of the reaction process,a reactor module containing 15 circular parallel channels could be used as module blocks,which can be stacked one by one to meet the required reactor performance and production capacity.The present results show that micro-reactors are quite suitable for HMF production.
基金financial supports from the National Natural Science Foundation of China(22378017,21776007)the National Key Research and Development Program of China(2022YFC2105604)are acknowledged。
文摘Thermocatalytic CO_(2) hydrogenation with"green"H_(2) is one of the most promising carbon-negative technologies,wherein oxygen vacancy engineering serves as a novel strategy to boost the catalytic performance of oxide-containing catalysts.To provide theoretical guidance and promote technical progress in this important field,the status and prospect of oxygen vacancy-boosted thermocatalytic CO_(2) hydrogenation have been thoroughly reviewed herein.Specifically,fundamentals including origin,construction,characterization,and function of oxygen vacancies will be systematically summarized and oxygen vacancy-boosted hydrogenation reactions including methanation,reverse water-gas shift(RWGS),methanol synthesis,and other hydrogenation processes will be comprehensively introduced.In addition,challenges and opportunities from the perspective of engineering strategies,promoting effects,and mediating mechanisms of oxygen vacancies will be succinctly proposed.Overall,this review is expected to gain more insights into the role of oxygen vacancies and shed new light on the design of efficient oxide-containing catalysts.
基金financial support from the National Natural Science Foundation of China (No. U1862102)the Fundamental Research Funds for the Central Universities (XK1802-1, JD1819)
文摘Four kinds of cryptomelane-type octahedral molecular sieve(OMS)-2-X(the X represents the molar ratio of KMnO4/MnAc2) were prepared as catalytic materials for ozone decomposition through a one-step hydrothermal reaction of KMnO4 and MnAc2, by changing their molar ratios. These samples were characterized by N2 adsorption–desorption, X-ray di raction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), temperature programmed reduction by H2(H2-TPR) and X-ray photoelectron spectroscopy(XPS). Among them, the OMS-2-0.7 sample showed the best O3 conversion of 92% under high relative humidity(RH) of 90% and gas hourly space velocity of 585,000 h-1. This was accordingly thought as a possible way for purifying ozone-containing waste gases under high RH atmospheres. The e ciency of ozone decomposition of the prepared OMS-2-X sample was found to be related to specific surface area, particle size, surface oxygen vacancies, and Mn3+ cation amounts. The one-step hydrothermal synthesis was shown to be a simple method to prepare the considerably active OMS-2 solids for ozone decomposition.
基金financially supported by the National Natural Science Foundation of China (Nos.21776007,21403012,21473185,U1532117)the Fundamental Research Funds for the Central Universities (No.buctrc201311)
文摘Nanosheet(S) and nanoplate(P) γ-Al_2O_3 were synthesized by simple hydrothermal methods and employed as supports for Ni catalysts in CO_2 methanation.Both of the nanostructured Ni/Al_2O_3 catalysts displayed good activity.In comparison,the Ni/Al_2O_3-S catalyst showed higher CO_2 conversion than the Ni/Al_2O_3-P counterpart at the reaction temperature ranging from 250 to 400 °C.The physical and chemical properties of the catalysts were systematically characterized by N2 sorption,X-ray diffraction(XRD),high resolution-transmission electron microscopy(HR-TEM),hydrogen temperature-programmed reduction(H2-TPR) and CO_2 temperature-programmed desorption(CO_2-TPD) techniques.Higher specific surface area and stronger metal-support interactions were confirmed on the Ni/Al_2O_3-S catalyst,which may lead to smaller particle size of Ni nanoparticles.Moreover,the Ni/Al_2O_3-S catalyst possessed more abundant weak and medium basic sites,which would benefit the activation of CO_2.The smaller Ni size and more suitable basic sites may rationalize the superior activity of the Ni/Al_2O_3-S catalyst.Besides,the Ni/Al_2O_3-S catalyst exhibited excellent stability at 325 °C for 40 h.
基金Supported by National Natural Science Foundation of China(21776015)
文摘Design and preparation of novel advanced carbon materials with unique architecture and functional groups is of great significance.Herein,a spongy acetylenic carbon material(SACM) was prepared through mechanochemical reaction of CaC2 and chlorinated rubber in a planetary ball mill at ambient temperature.Its composition and structure were characterized,and its electrochemical properties and adsorption performance for Hg^2+ were studied.The SACM is composed of submicron spongy aggregates with high carbon content(81.8%) and specific area(503.9 m^2·g^-1),rich porosity and acetylenic groups.The SACM exhibits excellent adsorption for Hg2+with saturated adsorption amount being 157.1 mg·g^-1,which is superior to conventional carbon materials.Further,it exhibits good electrochemical performance with low equivalent series resistance(0.50 Ω),excellent cycling stability and ideal double layer capacitive behavior.This paper provides a novel and universal synthesis method of spongy carbon materials,and better results can be expected through tuning the pore structure,graphitization degree,and heteroatoms of the target carbon materials.
基金supported by Beijing Natural Science Foundation(No.Z210016).
文摘The ordered membrane electrode assembly(MEA)has gained much attention because of its potential in improving mass transfer.Here,a comprehensive study was conducted on the influence of the patterned microporous layer(MPL)on the proton exchange membrane fuel cell performances.When patterned MPL is employed,grooves are generated between the catalyst layer and the gas diffusion layer.It is found that the grooves do not increase the contact resistance,and it is beneficial for water retention.When the MEA works under low humidity scenarios,the MEA with patterned MPL illustrated higher performance,due to the reduced inner resistance caused by improved water retention,leading to increased ionic conductivity.However,when the humidity is higher than 80%or working under high current density,the generated water accumulated in the grooves and hindered the oxygen mass transport,leading to a reduced MEA performance.
基金supported by the National Key R&D Program of China (Nos. 2016YFC0207104 and 2017YFC0211802)the National Natural Science Foundation of China (NSFC) (No. 21876191)the Youth Innovation Promotion Association, Chinese Academy of Sciences (No. 2017064)
文摘O3 decomposition catalysts with excellent performance still need to be developed. In this study, Ag-modified manganese oxides(AgMnOx) were synthesized by a simple co-precipitation method. The effect of calcination temperature on the activity of MnOx and AgMnOxcatalysts was investigated. The effect of the amount of Ag addition on the activity and structure of the catalysts was further studied by activity testing and characterization by a variety of techniques. The activity of 8%AgMnOxfor ozone decomposition was significantly enhanced due to the formation of the Ag1.8 Mn8 O16 structure, indicating that this phase has excellent performance for ozone decomposition.The weight content of Ag1.8 Mn8 O16 in the 8%AgMnOxcatalyst was only about 33.76%, which further indicates the excellent performance of the Ag1.8 Mn8 O16 phase for ozone decomposition. The H2 temperature programmed reduction(H2-TPR) results indicated that the reducibility of the catalysts increased due to the formation of the Ag1.8 Mn8 O16 structure.This study provides guidance for a follow-up study on Ag-modified manganese oxide catalysts for ozone decomposition.
基金supported by the National Key Research and Development Program of China (2017YFA0206500)the National Natural Science Foundation of China (21671014)the Fundamental Research Funds for the Central Universities (buctrc201522)
文摘Doped phosphide is promising in earthabundant element based catalysts for hydrogen evolution reaction(HER). Here we employ ammonium hypophosphite(NH4H2PO2) to synthesize a novel parallel doped catalyst,nitrogen doped molybdenum phosphide nanoparticles(NPs)supported on nitrogen doped carbon nanotubes(N-MoP/N-CNTs). The NH4H2PO2 as a bifunctional agent severs as both phosphidation agent and nitrogen source, which makes the synthetic route simple and efficient. The as-obtained parallel doped N-MoP/N-CNTs show an overpotential of 103±5 mV at 10 mA cm-2, which is 140 mV lower than that of MoP NPs. The enhanced HER performance is attributed to the electronic effect by doped MoP and CNTs supports. This work provides a facile route to synthesize doped phosphides for the potential applications in hydrogen energy.
基金financially supported by the National Natural Science Foundation of China(Nos.U1862102,21976012)the Fundamental Research Funds for the Central Universities(XK1802-1,JD2016)。
文摘Manganese oxides supported by ZSM-5 zeolite(Mn/ZSM-5) as well as their further modified by Ce promoter were achieved by simple impregnation method for ozone catalytic decomposition. The yCe20Mn/ZSM-5–81 catalyst with 8% Ce loading showed the highest catalytic activity at relative humidity of 50% and a space velocity of 360 L/(g × hr), giving 93% conversion of 600 ppm O_(3) after 5 hr. Moreover, this sample still maintained highly activity and stability in humid air with 50%–70% relative humidity. Series of physicochemical characterization including X-ray diffraction, temperature-programmed technology(NH_3-TPD and H_(2)-TPR), X-ray photoelectron spectroscopy and oxygen isotopic exchange were introduced to disclose the structure-performance relationship. The results indicated that moderate Si/Al ratio(81) of zeolite support was beneficial for ozone decomposition owing to the synergies of acidity and hydrophobicity. Furthermore, compared with 20 Mn/ZSM-5-81, Ce doping could enhance the amount of low valance manganese(such as Mn^(2+) and Mn^(3+)). Besides, the Ce^(3+)/Ce^(4+) ratio of 8Ce20Mn/ZSM-5-81 sample was higher than that of 4Ce_(2)0 Mn/ZSM-5-81. Additionally, the synergy between the MnO_x and CeO_(2) could easily transfer electron via the redox cycle, thus resulting in an increased reducibility at low temperatures and high concentration of surface oxygen. This study provides important insights to the utilization of porous zeolite with high surface area to disperse active component of manganese for ozone decomposition.
基金the National Natural Science Foundation of China (Nos. U1862102, 22176010 and 21976012) for the financial supportthe Fundamental Research Funds for the Central Universities (Nos. XK1802-1, JD2117)。
文摘Pt catalysts with nitrogen-doped graphene oxide (GO) as support and CeO_(2)as promoter were prepared by impregnation method,and their catalytic oxidation of formaldehyde (HCHO) at room temperature was tested.The Pt-CeO_(2)/N-rGO (reduced GO) with a mass fraction of 0.7% Pt and 0.8%CeO_(2)exhibited an excellent catalytic performance with the 100% conversion of HCHO at room temperature.Physicochemical characterization demonstrated that nitrogendoping greatly increased the defect degree and the specific surface area of GO,enhanced the dispersion of Pt and promoted more zero-valent Pt.The synergistic effect between CeO_(2)and Pt was also beneficial to the dispersion of Pt.Nitrogen-doping promoted the production of more Ce3+ions,generating more oxygen vacancies,which was conducive to O_(2)adsorption.As a result,the catalyst exhibited enhanced redox properties,leading to the best catalytic activity.Finally,an attempt to propose the reaction mechanism of HCHO oxidation has been made.
基金supported by the National Natural Science Foundation of China(Nos.21876009,21677008)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019A18)the Fundamental Research Funds for the Central Universities(Nos.JD2110,PY2103).
文摘Red mud,as a solid waste produced during the alumina production,can cause severe ecoenvironmental pollution and health risks to human.Therefore,the resourcing of this type of solid waste is an effective way for the sustainable development.This paper reviews the recent progress on red mud-based catalysts for the removal of typical air pollutants,such as the catalytic reduction of nitrogen oxides(NO_(x))by NH_(3)(NH_(3)-SCR)and the catalytic oxidation of CO and volatile organic compounds(VOCs).The factors influencing the catalytic performance and the structure–activity relationship have been discussed.Future prospects and directions for the development of such catalysts are also proposed.This review would benefit for the high value-added utilizations of red mud in mitigating atmospheric pollutions.
基金Project supported by the National Natural Science Foundation of China(22276010,21876009)National Engineering Laboratory for Mobile Source Emission Control Technology(NELMS2019A18)the Fundamental Research Funds for the Central Universities(PY2103,JD2110).
文摘An environmentally benign WO_(3) wrapped cubic CeO_(2) core-shell catalyst(Ce@W)was developed for the selective catalytic reduction of NO_(x) with NH_(3).Compared with CeW particles prepared via the conventional co-precipitation method,this core-shell catalyst not only displays higher tolerance to SO_(2) and H_(2)O,but also exhibits a wider activity tempe rature window of 250-450℃,in which NO_(x)conversion and N_(2) selectivity reaches 100%.The improved performance of Ce@W catalysts can be contributed to the strong interactions between CeO_(2)(100) and WO_(3),which generates more Ce^(3+) and surface chemisorbed oxygen.In situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)reveal that the more thermally stable Br?nsted acid sites on Ce@W lead to its excellent high-temperature activity.
基金supported by the National Natural Science Foundation of China(Nos.21971008 and 22279004)Beijing Natural Science Foundation(No.Z210016)Fundamental Research Funds for the Central Universities(No.buctrc201916).
文摘Electrochemical coupling hydrogen evolution with biomass reforming reaction(named electrochemical hydrogen and chemical cogeneration(EHCC)),which realizes green hydrogen production and chemical upgrading simultaneously,is a promising method to build a carbon-neutral society.Herein,we analyze the EHCC process by considering the market assessment.The ethanol to acetic acid and hydrogen approach is the most feasible for large-scale hydrogen production.We develop AuCu nanocatalysts,which can selectively oxidize ethanol to acetic acid(>97%)with high long-term activity.The isotopic and in-situ infrared experiments reveal that the promoted water dissociation step by alloying contributes to the enhanced activity of the partial oxidation reaction path.A flow-cell electrolyzer equipped with the AuCu anodic catalyst achieves the steady production of hydrogen and acetic acid simultaneously in both high selectivity(>90%),demonstrating the potential scalable application for green hydrogen production with low energy consumption and high profitability.
基金supported by the National Natural Science Foundation of China (21571012)
文摘Water electrolysis is considered to be an effective way to fabricate hydrogen, and it is desirable to find the highly efficient, inexpensive and good durability bifunctional electrocatalysts for overall water splitting.In this paper, we synthesis a unique structured catalyst that was composed by Co_9S_8 nanowires and nickel cobalt layered double hydroxide(NiCo-LDH) nanosheets. The ultrathin nanosheets decorated on the Co_9S_8 nanoarrays offer large specific surface area, numerous active edge sites and excellent electrical conductivity for fast electron transfer. Benefiting from this heterogeneous structure, the catalyst presents excellent catalytic performance in alkaline media. It requires 168 mV to reach current density of 10 mA/cm^2 for HER and 278 m V to reach current density of 30 mA/cm^2 for OER. When used as electrode in a homemade two-electrode system, it only needs t a voltage of 1.63 V to achieve current densities of 10 mA/cm^2, which proves Co_9S_8@NiCo LDH/NF as a superior bifunctional catalyst for water splitting.
基金financially supported by the National Key Research and Development Program of China (2017YFA0206500)the National Natural Science Foundation of China (21671014)the Fundamental Research Funds for the Central Universities (buctrc201823)
文摘It is urgent to develop low-cost but efficient oxygen reduction reaction(ORR)catalysts for the emerging clean energy devices of fuel cells based on proton exchange membrane.Herein,we report a facile method to covert the biomass of black fungus into an efficient ORR catalyst.The black fungus undergoes hydrothermal and pyrolysis processes to transform into carbon-based materials.The as-obtained BF-N-950 catalyst shows prominent ORR catalytic activities in both acidic and alkaline electrolytes with a half-wave potential reaching 0.77 and 0.91 V,respectively.A membrane electrolyte assembly was fabricated with the as-obtained BF-N-950 as the cathode catalyst which shows a high peak power density of255 mW cm^-2.The study shows the potential of converting conventional biomass into low-cost ORR catalyst,which is promising for the fuel cell technology.
