The slow kinetics at the cathode of oxygen reduction reaction(ORR)seriously limits the efficiencies of fuel cells and metal-air batteries.Pt,the state-of-the-art ORR electrocatalyst,suffers from high cost,low earth ab...The slow kinetics at the cathode of oxygen reduction reaction(ORR)seriously limits the efficiencies of fuel cells and metal-air batteries.Pt,the state-of-the-art ORR electrocatalyst,suffers from high cost,low earth abundance,and poor stability.Here a self-templated strategy based on metal-organic frameworks(MOFs)is proposed for the fabrication of hollow nitrogen-doped carbon spheres that are embedded with cobalt nanoparticles(Co/HNC).The Co/HNC manifests better ORR activities,methanol tolerance,and stability than commercial Pt/C.The high ORR performance of Co/NHC can be attributed to the hollow structure which provides enlarged electrochemically active surface area,the formation of more Co-N species,and the introduction of defects.This work highlights the significance of rational engineering of MOFs for enhanced ORR activity and stability and offers new routes to the design and synthesis of high-performance electrocatalysts.展开更多
In this work,we carried out both theoretical calculation and experimental studies to reveal the contribution of hollow geometry to the light utilization efficiency of the TiO_2 photocatalysts in diluted aqueous soluti...In this work,we carried out both theoretical calculation and experimental studies to reveal the contribution of hollow geometry to the light utilization efficiency of the TiO_2 photocatalysts in diluted aqueous solution.It is found that the single or multi-shelled hollow structures do not induce significant multiple reflections within the shells as widely believed in previous reports,and therefore the geometric factor has minimal contribution to the improvement of the light utilization efficiency of the photocatalyst.To design TiO_2 photocatalysts with higher activity,it is more appropriate to focus on the improvement of the crystallinity,diffusion,surface area,and dispersity of the catalysts,rather than their geometric shapes.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21673150 and 51922073)Natural Science Foundation of Jiangsu Province(No.BK20180097)。
文摘The slow kinetics at the cathode of oxygen reduction reaction(ORR)seriously limits the efficiencies of fuel cells and metal-air batteries.Pt,the state-of-the-art ORR electrocatalyst,suffers from high cost,low earth abundance,and poor stability.Here a self-templated strategy based on metal-organic frameworks(MOFs)is proposed for the fabrication of hollow nitrogen-doped carbon spheres that are embedded with cobalt nanoparticles(Co/HNC).The Co/HNC manifests better ORR activities,methanol tolerance,and stability than commercial Pt/C.The high ORR performance of Co/NHC can be attributed to the hollow structure which provides enlarged electrochemically active surface area,the formation of more Co-N species,and the introduction of defects.This work highlights the significance of rational engineering of MOFs for enhanced ORR activity and stability and offers new routes to the design and synthesis of high-performance electrocatalysts.
基金support from the U.S.Department of Energy,Office of Science,Basic Energy Sciences,Chemical Sciences,Geosciences,&Biosciences(CSGB)Division(DE-SC0002247)support from the National Natural Science Foundation of China(21501081,21571089,and 21401091)the Fundamental Research Funds for the Central Universities(SWU116010 and lzujbky-2015-19)
文摘In this work,we carried out both theoretical calculation and experimental studies to reveal the contribution of hollow geometry to the light utilization efficiency of the TiO_2 photocatalysts in diluted aqueous solution.It is found that the single or multi-shelled hollow structures do not induce significant multiple reflections within the shells as widely believed in previous reports,and therefore the geometric factor has minimal contribution to the improvement of the light utilization efficiency of the photocatalyst.To design TiO_2 photocatalysts with higher activity,it is more appropriate to focus on the improvement of the crystallinity,diffusion,surface area,and dispersity of the catalysts,rather than their geometric shapes.
