The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results in...The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results indicated that besides a small quantity of 6H-SiC, SiC NPs mainly consisted of 3C-SiC. The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra, respectively. The Cu2O modification can enhance the photocatalytic performance of SiC NPs, and the largest yields of methanol on SiC, Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153, 104 and 191μmol/g, respectively.展开更多
Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as p...Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as precursor,a novel noble-metal-free FeCo@NGC cocatalyst(nano-FeCo alloy@N-doped graphitized carbon) is fabricated by a simple pyrolysis method.Coupling with g-C3 N4, the optimal FeCo@NGC/g-C3N4 receives a boosted visible light driven photocatalytic H2 evolution rate of 42.2 μmol h-1, which is even higher than that of 1.0 wt% Pt modified g-C3N4 photocatalyst.Based on the results of density functional theory(DFT) calculations and practical experiment measurements,such outstanding photocatalytic performance of FeCo@NGC/g-C3N4 is mainly attributed to two aspects.One is the accelerated charge transfer behavior,induced by a photogene rated electrons secondary transfer performance on the surface of FeCo alloy nanoparticles.The other is related to the adjustment of H adsorption energy(approaching the standard hydrogen electrode potential) by the presence of external NGC thin layer.Both factors play key roles in the H2 evolution reaction.Such outstanding performance highlights an enormous potential of developing noble-metal-free bimetallic nano-alloy as inexpensive and efficient cocatalysts for solar applications.展开更多
The sluggish redox kinetics and shuttle effect of soluble polysulfides intermediate primarily restrict the electrochemical performance of lithium–sulfur(Li–S) batteries. To address this issue, rational design of hig...The sluggish redox kinetics and shuttle effect of soluble polysulfides intermediate primarily restrict the electrochemical performance of lithium–sulfur(Li–S) batteries. To address this issue, rational design of high–efficiency sulfur host is increasingly demanded to accelerate the polysulfides conversion during charge/discharge process. Herein, we propose a macro–mesoporous sulfur host(Co@NC), which comprises highly dispersed cobalt nanoparticles embedding in N–doped ultrathin carbon nanosheets. Co@NC is simply synthesized via a carbon nitride–derived pyrolysis approach. Owing to the highly conductive graphene–like matrix and well defined porous structure, the designed multifunctional Co@NC host enables rapid electron/ion transport, electrolyte penetration and effective sulfur trapping. More significantly,N heteroatoms and homogeneous Co nanocatalysts in the graphitic carbon nanosheets could serve as chemisorption sites as well as electrocatalytic centers for sulfur species. These Co–N active sites can synergistically facilitate the redox conversion kinetics and mitigate the shuttling of polysulfides, thus leading to improved electrochemical cycling performance of Li–S batteries. As a consequence, the S/Co@NC cathode demonstrates high initial specific capacity(1505 mA h g-1 at 0.1 C) and excellent cycling stability at 1 C over 300 cycles, giving rise to a capacity retention of 91.7% and an average capacity decline of 0.03%cycle-1.展开更多
Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes.In this work,one-dimensional coaxial core-she...Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes.In this work,one-dimensional coaxial core-shell carbon nanotubes@SiC nanotubes were successfully synthesized via in situ growth of SiC coatings on carbon nanotubes by a vapor-solid reaction between silicon vapor and carbon nanotubes.High-resolution transmission electron microscope images show that SiC and carbon nanotubes link to form a robust heterojunction with intrinsic atomic contact,which results in efficient separation of the photogenerated electron-hole pairs on SiC and electron transfer from SiC to carbon nanotubes.Compared with those of similar materials such as pure SiC nanocrystals and SiC nanotubes,the metal-free carbon nanotubes@SiC exhibits an enhanced photocatalytic activity for hydrogen evolution,which is attributed to the enhanced light absorption and the efficient interfacial charge transfer/separation brought about by their one-dimensional coaxial nanoheterostructures.Moreover,the photocatalytic stability of the metal-free carbon nanotubes@SiC was tested for over 20 h without any obvious decay.展开更多
Pursuing appropriate photo-active Li-ion storage materials and understanding their basic energy storage/conversion principle are pretty crucial for the rapidly developing photoassisted Li-ion batteries(PA-LIBs).Copper...Pursuing appropriate photo-active Li-ion storage materials and understanding their basic energy storage/conversion principle are pretty crucial for the rapidly developing photoassisted Li-ion batteries(PA-LIBs).Copper oxide(CuO)is one of the most popular candidates in both LIBs and photocatalysis.While CuO based PA-LIBs have never been reported yet.Herein,one-dimensional(1D)CuO nanowire arrays in situ grown on a three-dimensional(3D)copper foam support were employed as dualfunctional photoanode for both‘solar-to-electricity’and‘electricity-to-chemical’energy conversion in the PA-LIBs.It is found that light energy can be indeed stored and converted into electrical energy through the assembled CuO based PA-LIBs.Without external power source,the photo conversion efficiency of CuO based photocell reaches about 0.34%.Impressively,at a high current density of 4000 m A g^(-1),photoassisted discharge and charge specific capacity of CuO based PA-LIBs respectively receive 64.01%and 60.35%enhancement compared with the net electric charging and discharging process.Mechanism investigation reveals that photogenerated charges from CuO promote the interconversion between Cu^(2+)and Cu^(+)during the discharging/charging process,thus forcing the lithium storage reaction more completely and increasing the specific capacity of the PA-LIBs.This work can provide a general principle for the development of other high-efficient semiconductor-based PA-LIBs.展开更多
The exploration of high-efficiency transition metal-nitrogen-carbon(M-N-C)catalysts is crucial for accelerating the kinetics of oxygen reduction/oxygen evolution reactions(ORR/OER).Fine-tuning the distribution of acce...The exploration of high-efficiency transition metal-nitrogen-carbon(M-N-C)catalysts is crucial for accelerating the kinetics of oxygen reduction/oxygen evolution reactions(ORR/OER).Fine-tuning the distribution of accessible metal sites and the correlated triphase interfaces within the M-N-C catalysts holds significant promise.In this study,we present an integrated electrocatalyst comprised of tip-enriched NiFe nanoalloys encapsulated within N-doped carbon nanotubes(NiFe@CNTs),synthesized using an in-situ wet-electrochemistry mediated approach.The well-defined NiFe@CNTs catalyst possesses a porous heterostructure,synergistic M-N_(x)-C active sites,and intimate micro interfaces,facilitating accelerated redox kinetics.This leads to exceptional OER/ORR activities with a low overallΔE of 630 mV.Experimental results and density functional theory calculations unveil the predominant electronic interplay between the apical bimetallic sites and neighboring N-doped CNTs,thereby enhancing the binding of intermediates on NiFe@CNTs.Molecular dynamics simulations reveal that the local gas-liquid environment surrounding NiFe@CNTs favors the diffusion/adsorption of the OH-/O_(2)reactants.Consequently,NiFe@CNTs contribute to high-performance aqueous Zn-Air batteries(ZABs),exhibiting a high gravimetric energy den-sity(936 Wh kgZn-1)and superb cycling stability(>425 h)at 20 mA cm^(-2).Furthermore,solid-state ZABs based on NiFe@CNTs demonstrate impressive electrochemical performance(e.g.,peak power density of 108 mW cm-2,specific energy of 1003 Wh kgZn-1)and prominent flexibility.This work illuminates a viable strategy for constructing metal site-specific,cobalt-free,and integrated M-N-C electrocatalysts for multifunctional catalysis and advanced/flexible energy storage applications.展开更多
In the realm of photoenergy conversion,the scarcity of efficient light-driven semiconductors poses a significant obstacle to the advancement of photocatalysis,highlighting the critical need for researchers to explore ...In the realm of photoenergy conversion,the scarcity of efficient light-driven semiconductors poses a significant obstacle to the advancement of photocatalysis,highlighting the critical need for researchers to explore novel semiconductor materials.Herein,we present the inaugural synthesis of a novel semiconductor,CdNCN,under mild conditions,while shedding light on its formation mechanism.By effectively harnessing the[NCN]^(2⁻)moiety in the thiourea process,we successfully achieve the one-pot synthesis of CdNCN-CdS heterostructure photocatalysts.Notably,the optimal CdNCN-CdS sample demonstrates a hydrogen evolution rate of 14.7 mmol g^(-1)h^(-1)under visible light irradiation,establishing itself as the most efficient catalyst among all reported CdS-based composites without any cocatalysts.This outstanding hydrogen evolution performance of CdNCN-CdS primarily arises from two key factors:i)the establishment of an atomic-level N-Cd-S heterostructure at the interface between CdNCN and CdS,which facilitating highly efficient electron transfer;ii)the directed transfer of electrons to the(110)crystal plane of CdNCN,promoting optimal hydrogen adsorption and active participation in the hydrogen evolution reaction.This study provides a new method for synthesizing CdNCN materials and offers insights into the design and preparation of innovative atomic-level composite semiconductor photocatalysts.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 20906034)the Key Academic Program of the 3rd Phase "211 Project" of South China Agricultural University (Grant No. 2009B010100001)China Postdoctoral Science Foundation (Grant No. 20080430820)
文摘The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results indicated that besides a small quantity of 6H-SiC, SiC NPs mainly consisted of 3C-SiC. The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra, respectively. The Cu2O modification can enhance the photocatalytic performance of SiC NPs, and the largest yields of methanol on SiC, Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153, 104 and 191μmol/g, respectively.
基金supported by the National Natural Science Foundation of China (21972048, 21802046)the Natural Science Foundation of Guangdong Province (Nos. 2019A1515011138, 2017A030313090, 2017A030310086, 2018A0303130018)。
文摘Cocatalysts play important roles in improving the activity and stability of most photocatalysts.It is of great significance to develop economical,efficient and stable cocatalysts.Herein,using Na2CoFe(CN)6 complex as precursor,a novel noble-metal-free FeCo@NGC cocatalyst(nano-FeCo alloy@N-doped graphitized carbon) is fabricated by a simple pyrolysis method.Coupling with g-C3 N4, the optimal FeCo@NGC/g-C3N4 receives a boosted visible light driven photocatalytic H2 evolution rate of 42.2 μmol h-1, which is even higher than that of 1.0 wt% Pt modified g-C3N4 photocatalyst.Based on the results of density functional theory(DFT) calculations and practical experiment measurements,such outstanding photocatalytic performance of FeCo@NGC/g-C3N4 is mainly attributed to two aspects.One is the accelerated charge transfer behavior,induced by a photogene rated electrons secondary transfer performance on the surface of FeCo alloy nanoparticles.The other is related to the adjustment of H adsorption energy(approaching the standard hydrogen electrode potential) by the presence of external NGC thin layer.Both factors play key roles in the H2 evolution reaction.Such outstanding performance highlights an enormous potential of developing noble-metal-free bimetallic nano-alloy as inexpensive and efficient cocatalysts for solar applications.
基金the Guangdong Provincial Natural Science Foundation(nos.2017A030313283,2017A030313083)National Natural Science Foundation of China(NSFC,no.51602109)。
文摘The sluggish redox kinetics and shuttle effect of soluble polysulfides intermediate primarily restrict the electrochemical performance of lithium–sulfur(Li–S) batteries. To address this issue, rational design of high–efficiency sulfur host is increasingly demanded to accelerate the polysulfides conversion during charge/discharge process. Herein, we propose a macro–mesoporous sulfur host(Co@NC), which comprises highly dispersed cobalt nanoparticles embedding in N–doped ultrathin carbon nanosheets. Co@NC is simply synthesized via a carbon nitride–derived pyrolysis approach. Owing to the highly conductive graphene–like matrix and well defined porous structure, the designed multifunctional Co@NC host enables rapid electron/ion transport, electrolyte penetration and effective sulfur trapping. More significantly,N heteroatoms and homogeneous Co nanocatalysts in the graphitic carbon nanosheets could serve as chemisorption sites as well as electrocatalytic centers for sulfur species. These Co–N active sites can synergistically facilitate the redox conversion kinetics and mitigate the shuttling of polysulfides, thus leading to improved electrochemical cycling performance of Li–S batteries. As a consequence, the S/Co@NC cathode demonstrates high initial specific capacity(1505 mA h g-1 at 0.1 C) and excellent cycling stability at 1 C over 300 cycles, giving rise to a capacity retention of 91.7% and an average capacity decline of 0.03%cycle-1.
基金supported by the National Natural Science Foundation of China(21673083,21802046)the Guangdong Provincial Science and Technology Project(2017A030313090,2014A030310427)~~
文摘Considerable research efforts have been devoted to developing novel photocatalysts with increased performances by hybridizing inorganic nanomaterials with carbon nanotubes.In this work,one-dimensional coaxial core-shell carbon nanotubes@SiC nanotubes were successfully synthesized via in situ growth of SiC coatings on carbon nanotubes by a vapor-solid reaction between silicon vapor and carbon nanotubes.High-resolution transmission electron microscope images show that SiC and carbon nanotubes link to form a robust heterojunction with intrinsic atomic contact,which results in efficient separation of the photogenerated electron-hole pairs on SiC and electron transfer from SiC to carbon nanotubes.Compared with those of similar materials such as pure SiC nanocrystals and SiC nanotubes,the metal-free carbon nanotubes@SiC exhibits an enhanced photocatalytic activity for hydrogen evolution,which is attributed to the enhanced light absorption and the efficient interfacial charge transfer/separation brought about by their one-dimensional coaxial nanoheterostructures.Moreover,the photocatalytic stability of the metal-free carbon nanotubes@SiC was tested for over 20 h without any obvious decay.
基金supported by the Laboratory of Lingnan Modern Agriculture Project(NZ2021029)the National Natural Science Foundation of China(Nos.21802046 and 21972048)。
文摘Pursuing appropriate photo-active Li-ion storage materials and understanding their basic energy storage/conversion principle are pretty crucial for the rapidly developing photoassisted Li-ion batteries(PA-LIBs).Copper oxide(CuO)is one of the most popular candidates in both LIBs and photocatalysis.While CuO based PA-LIBs have never been reported yet.Herein,one-dimensional(1D)CuO nanowire arrays in situ grown on a three-dimensional(3D)copper foam support were employed as dualfunctional photoanode for both‘solar-to-electricity’and‘electricity-to-chemical’energy conversion in the PA-LIBs.It is found that light energy can be indeed stored and converted into electrical energy through the assembled CuO based PA-LIBs.Without external power source,the photo conversion efficiency of CuO based photocell reaches about 0.34%.Impressively,at a high current density of 4000 m A g^(-1),photoassisted discharge and charge specific capacity of CuO based PA-LIBs respectively receive 64.01%and 60.35%enhancement compared with the net electric charging and discharging process.Mechanism investigation reveals that photogenerated charges from CuO promote the interconversion between Cu^(2+)and Cu^(+)during the discharging/charging process,thus forcing the lithium storage reaction more completely and increasing the specific capacity of the PA-LIBs.This work can provide a general principle for the development of other high-efficient semiconductor-based PA-LIBs.
基金supported by the Natural Science Foundation of Guangdong Province(No.2023A1515030131,2022A1515010476)the National Natural Science Foundation of China(22078118).
文摘The exploration of high-efficiency transition metal-nitrogen-carbon(M-N-C)catalysts is crucial for accelerating the kinetics of oxygen reduction/oxygen evolution reactions(ORR/OER).Fine-tuning the distribution of accessible metal sites and the correlated triphase interfaces within the M-N-C catalysts holds significant promise.In this study,we present an integrated electrocatalyst comprised of tip-enriched NiFe nanoalloys encapsulated within N-doped carbon nanotubes(NiFe@CNTs),synthesized using an in-situ wet-electrochemistry mediated approach.The well-defined NiFe@CNTs catalyst possesses a porous heterostructure,synergistic M-N_(x)-C active sites,and intimate micro interfaces,facilitating accelerated redox kinetics.This leads to exceptional OER/ORR activities with a low overallΔE of 630 mV.Experimental results and density functional theory calculations unveil the predominant electronic interplay between the apical bimetallic sites and neighboring N-doped CNTs,thereby enhancing the binding of intermediates on NiFe@CNTs.Molecular dynamics simulations reveal that the local gas-liquid environment surrounding NiFe@CNTs favors the diffusion/adsorption of the OH-/O_(2)reactants.Consequently,NiFe@CNTs contribute to high-performance aqueous Zn-Air batteries(ZABs),exhibiting a high gravimetric energy den-sity(936 Wh kgZn-1)and superb cycling stability(>425 h)at 20 mA cm^(-2).Furthermore,solid-state ZABs based on NiFe@CNTs demonstrate impressive electrochemical performance(e.g.,peak power density of 108 mW cm-2,specific energy of 1003 Wh kgZn-1)and prominent flexibility.This work illuminates a viable strategy for constructing metal site-specific,cobalt-free,and integrated M-N-C electrocatalysts for multifunctional catalysis and advanced/flexible energy storage applications.
基金financially supported by the National Natural Science Foundation of China(Nos.22078118,22274059 and 42277219)the Natural Science Foundation of Guangdong Province,China(Nos.2023A1515010740 and 2023A1515030131).
文摘In the realm of photoenergy conversion,the scarcity of efficient light-driven semiconductors poses a significant obstacle to the advancement of photocatalysis,highlighting the critical need for researchers to explore novel semiconductor materials.Herein,we present the inaugural synthesis of a novel semiconductor,CdNCN,under mild conditions,while shedding light on its formation mechanism.By effectively harnessing the[NCN]^(2⁻)moiety in the thiourea process,we successfully achieve the one-pot synthesis of CdNCN-CdS heterostructure photocatalysts.Notably,the optimal CdNCN-CdS sample demonstrates a hydrogen evolution rate of 14.7 mmol g^(-1)h^(-1)under visible light irradiation,establishing itself as the most efficient catalyst among all reported CdS-based composites without any cocatalysts.This outstanding hydrogen evolution performance of CdNCN-CdS primarily arises from two key factors:i)the establishment of an atomic-level N-Cd-S heterostructure at the interface between CdNCN and CdS,which facilitating highly efficient electron transfer;ii)the directed transfer of electrons to the(110)crystal plane of CdNCN,promoting optimal hydrogen adsorption and active participation in the hydrogen evolution reaction.This study provides a new method for synthesizing CdNCN materials and offers insights into the design and preparation of innovative atomic-level composite semiconductor photocatalysts.
