Molybdenum carbides are highly active for CO2 conversion to CO via the reverse water-gas shift(RWGS)reaction, however the large grain size up to micrometers renders its relatively lower active sites utilization effici...Molybdenum carbides are highly active for CO2 conversion to CO via the reverse water-gas shift(RWGS)reaction, however the large grain size up to micrometers renders its relatively lower active sites utilization efficiency while generating CH4 as a by-product. In this work, a homogeneously dispersed molybdenum carbide hybrid catalyst with sub-nanosized cluster(the average size as small as 0.5 nm) is prepared via a facile carbothermal treatment for highly selective CO2-CO reduction. The partially disordered Mo2C clusters are characterized by synchrotron high-resolution XRD and atomic resolution HAADF-STEM analysis, for which the source cause of the disorder is pinpointed by XAFS analysis to be the nitrogen intercalants from the carbonaceous precursor. The partially disordered Mo2C clusters show a RWGS rate as high as 184.4 μmol gMo2C-1s-1 at 400 ℃ with a superior selectivity toward CO(> 99.5%). This work 2 highlights a facile strategy for fabricating highly dispersed and partially disordered Mo2C clusters at a sub-nano size with beneficial N-doping for delivering high catalytic activity and operational stability.展开更多
Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geome...Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geometry,determination of which is challenging,particularly for clusters formed by multiple elements.In this study,we investigate the geometries and electronic structures of binary V_(n)C_(3)-(n=1-6)clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory.The adiabatic detachment energies of V_(n)C_(3)-,or equally,the electron affinities of V_(n)C_(3),have been determined from the measured photoelectron spectra.Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters,i.e.,the C-C interactions present in small clusters are replaced by V-C and/or V-V interactions in larger ones.We further explore the composition dependent formation of cubic or cube-like structures in 8-atom VnCm(n+m=8)clusters.展开更多
基金the National Natural Science Foundation of China(21872144,21972140 and 91645117)Liaoning Revitalization Talents Program(XLYC1907053)+2 种基金CAS Youth Innovation Promotion Association(2018220)Talents Innovation Project of Dalian City(2017RQ032 and 2016RD04)China Postdoctoral Science Foundation(2019TQ0314,2018M641726 and 2019M661146)。
文摘Molybdenum carbides are highly active for CO2 conversion to CO via the reverse water-gas shift(RWGS)reaction, however the large grain size up to micrometers renders its relatively lower active sites utilization efficiency while generating CH4 as a by-product. In this work, a homogeneously dispersed molybdenum carbide hybrid catalyst with sub-nanosized cluster(the average size as small as 0.5 nm) is prepared via a facile carbothermal treatment for highly selective CO2-CO reduction. The partially disordered Mo2C clusters are characterized by synchrotron high-resolution XRD and atomic resolution HAADF-STEM analysis, for which the source cause of the disorder is pinpointed by XAFS analysis to be the nitrogen intercalants from the carbonaceous precursor. The partially disordered Mo2C clusters show a RWGS rate as high as 184.4 μmol gMo2C-1s-1 at 400 ℃ with a superior selectivity toward CO(> 99.5%). This work 2 highlights a facile strategy for fabricating highly dispersed and partially disordered Mo2C clusters at a sub-nano size with beneficial N-doping for delivering high catalytic activity and operational stability.
基金the Doctoral Start-up Funding of Zhengzhou University of Light Industry(No.2017BSJJ030)Henan Province Science Fund for Excellent Young Scholars(No.202300410494)+4 种基金the Beijing Municipal Science and Technology Commission(No.Z191100007219009)for supportsthe VSC(Flemish Supercomputer Center),funded by the Research Foundation-Flanders(FWO)the Flemish Government-department EWIthe support of Xi’an Jiaotong University via the“Young Talent Support Plan”the“Fundamental Research Funds for Central Universities”。
文摘Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geometry,determination of which is challenging,particularly for clusters formed by multiple elements.In this study,we investigate the geometries and electronic structures of binary V_(n)C_(3)-(n=1-6)clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory.The adiabatic detachment energies of V_(n)C_(3)-,or equally,the electron affinities of V_(n)C_(3),have been determined from the measured photoelectron spectra.Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters,i.e.,the C-C interactions present in small clusters are replaced by V-C and/or V-V interactions in larger ones.We further explore the composition dependent formation of cubic or cube-like structures in 8-atom VnCm(n+m=8)clusters.
