Single-molecule tip-enhanced Raman spectroscopy(TERS)has emerged as an important technique for structural analysis at sub-molecular scale.Here in this work,we report a TERS study of an isolated free-base porphyrin mol...Single-molecule tip-enhanced Raman spectroscopy(TERS)has emerged as an important technique for structural analysis at sub-molecular scale.Here in this work,we report a TERS study of an isolated free-base porphyrin molecule adsorbed on the Ag(100)surface at cryogenic temperature(~7 K).Site-dependent TERS spectra reveal distinct local vibrational information for the chemical constituents within a single molecule.Moreover,distinct spatial features among different Raman peaks can be resolved from the TERS mapping images.These images are found to associate with related vibrational modes,enabling to resolve the mode associated with N-H bonds at the sub-nanometer level.This study will provide deep insights into the symmetry of adsorption configurations and local vibrational information within a single molecule.展开更多
Electrocatalysis of CO_(2)reduction reaction is an effective way to convert CO_(2)into high value-added products,but the selectivity of Cu-based catalysts for C2+products needs to be improved due to the high energy ba...Electrocatalysis of CO_(2)reduction reaction is an effective way to convert CO_(2)into high value-added products,but the selectivity of Cu-based catalysts for C2+products needs to be improved due to the high energy barrier of C-C coupling.Therefore,a viable catalyst design strategy to decrease energy barrier of C-C coupling should be put forward.Here,a nanocavity-enriched CuPd single atom alloy(CuPd SAA)catalyst is designed to promote CC coupling process.The faradaic efficiency of CuPd SAA for ethylene and C_(2+)reaches 75.6%and 85.7%at-0.7 V versus reversible hydrogen electrode(RHE),respectively.Based on the results given by in situ characterization,the porous hollow structure dramatically increases the ratio of the linear-bond*CO,thus enhancing the faradaic efficiency for ethylene.Density functional theory(DFT)calculation reveals that the Pd doping can regulate the electronic structure of neighboring Cu atoms to decrease the energy barrier of C-C coupling,further improving the faradaic efficiency.This work provides a new idea for designing catalyst with high selectivity for ethylene.展开更多
基金supported by the National Key R&D Program of China(No.2016YFA0200600)the National Natural Science Foundation of China,the Chinese Academy of Sciences+1 种基金Anhui Initiative in Quantum Information TechnologiesAtif Ghafoor acknowledges support by the China Scholarship Council
文摘Single-molecule tip-enhanced Raman spectroscopy(TERS)has emerged as an important technique for structural analysis at sub-molecular scale.Here in this work,we report a TERS study of an isolated free-base porphyrin molecule adsorbed on the Ag(100)surface at cryogenic temperature(~7 K).Site-dependent TERS spectra reveal distinct local vibrational information for the chemical constituents within a single molecule.Moreover,distinct spatial features among different Raman peaks can be resolved from the TERS mapping images.These images are found to associate with related vibrational modes,enabling to resolve the mode associated with N-H bonds at the sub-nanometer level.This study will provide deep insights into the symmetry of adsorption configurations and local vibrational information within a single molecule.
基金financially supported by the National Natural Science Foundation of China(Nos.50835002 and 51105102)。
文摘Electrocatalysis of CO_(2)reduction reaction is an effective way to convert CO_(2)into high value-added products,but the selectivity of Cu-based catalysts for C2+products needs to be improved due to the high energy barrier of C-C coupling.Therefore,a viable catalyst design strategy to decrease energy barrier of C-C coupling should be put forward.Here,a nanocavity-enriched CuPd single atom alloy(CuPd SAA)catalyst is designed to promote CC coupling process.The faradaic efficiency of CuPd SAA for ethylene and C_(2+)reaches 75.6%and 85.7%at-0.7 V versus reversible hydrogen electrode(RHE),respectively.Based on the results given by in situ characterization,the porous hollow structure dramatically increases the ratio of the linear-bond*CO,thus enhancing the faradaic efficiency for ethylene.Density functional theory(DFT)calculation reveals that the Pd doping can regulate the electronic structure of neighboring Cu atoms to decrease the energy barrier of C-C coupling,further improving the faradaic efficiency.This work provides a new idea for designing catalyst with high selectivity for ethylene.
