Electrical properties and magnetoresistance have been studied in two series of xAg-La0.67（Ca0.65Ba0.35）0.33MnO3 and xPd-La0.67（Ca0.65Ba0.35）0.33MnO3 （abbreviated by xAg-LCBMO and xPd-LCBMO） composites. Both Pd a...Electrical properties and magnetoresistance have been studied in two series of xAg-La0.67（Ca0.65Ba0.35）0.33MnO3 and xPd-La0.67（Ca0.65Ba0.35）0.33MnO3 （abbreviated by xAg-LCBMO and xPd-LCBMO） composites. Both Pd and Ag addition induce a decrease in resistivity and an increase in temperature at which the resistivity reaches its maximum. This is mainly due to the improvement of grain boundaries caused by the segregation of good conductive metal grains on the grain boundaries/surfaces. In addition, both Pd and Ag addition induce a large enhancement of room temperature magnetoresistance （RTMR）. Note that 27% molar ratio of Ag addition induces a large RTMR of about 70%, about ten times larger than pure LCBMO, whereas 27% molar ratio Pd addition brings a much larger RTMR of about 170%. The large enhancements of MR can be attributed to the decrease in resistivity of the samples caused by the good conductive metal. On the other hand, the polarization of Pd atoms near the Mn ions on the grain surfaces/boundaries plays a very im-portant role in the increase in MR, which induces a large number of spin clusters in Pd-added samples.展开更多
The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d c...The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d core lines show the presence of nanometer-sized silver particles in each of the annealed samples,even if these Ag 3d lines appear to be very different from each other. We explain these results as a different interaction of silver with the two glasses matrix,which leads to a different nucleation rate of the Ag clusters.展开更多
Amidst the development of photoelectrochemical(PEC)CO_(2) conversion toward practical application,the production of high-value chemicals beyond C1 compounds under mild conditions is greatly desired yet challenging.Her...Amidst the development of photoelectrochemical(PEC)CO_(2) conversion toward practical application,the production of high-value chemicals beyond C1 compounds under mild conditions is greatly desired yet challenging.Here,through rational PEC device design by combining Au-loaded and N-doped TiO_(2) plate nanoarray photoanode with Zn-doped Cu_(2)O dark cathode,efficient conversion of CO_(2) to CH3COOH has been achieved with an outstanding Faradaic efficiency up to 58.1%(91.5%carbon selectivity)at 0.5 V vs.Ag/AgCl.Temperature programmed desorption and in situ Raman spectra reveal that the Zn-dopant in Cu_(2)O plays multiple roles in selective catalytic CO_(2) conversion,including local electronic structure manipulation and active site modification,which together promote the formation of intermediate*CH2/*CH3 for C-C coupling.Apart from that,it is also unveiled that the sufficient electron density provided by the Au-loaded and N-doped TiO_(2) plate nanoarray photoanode plays an equally important role by initiating multi-electron CO_(2) reduction.This work provides fresh insights into the PEC system design to reach the multi-electron reduction reaction and facilitate the C-C coupling reaction toward high-value multicarbon(C2+)chemical production via CO_(2) conversion.展开更多
文摘Electrical properties and magnetoresistance have been studied in two series of xAg-La0.67（Ca0.65Ba0.35）0.33MnO3 and xPd-La0.67（Ca0.65Ba0.35）0.33MnO3 （abbreviated by xAg-LCBMO and xPd-LCBMO） composites. Both Pd and Ag addition induce a decrease in resistivity and an increase in temperature at which the resistivity reaches its maximum. This is mainly due to the improvement of grain boundaries caused by the segregation of good conductive metal grains on the grain boundaries/surfaces. In addition, both Pd and Ag addition induce a large enhancement of room temperature magnetoresistance （RTMR）. Note that 27% molar ratio of Ag addition induces a large RTMR of about 70%, about ten times larger than pure LCBMO, whereas 27% molar ratio Pd addition brings a much larger RTMR of about 170%. The large enhancements of MR can be attributed to the decrease in resistivity of the samples caused by the good conductive metal. On the other hand, the polarization of Pd atoms near the Mn ions on the grain surfaces/boundaries plays a very im-portant role in the increase in MR, which induces a large number of spin clusters in Pd-added samples.
基金This work was partially supported by MIUR-FIRB (RBNE012N3X-005) and by PAT-FAPVU projects.
文摘The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d core lines show the presence of nanometer-sized silver particles in each of the annealed samples,even if these Ag 3d lines appear to be very different from each other. We explain these results as a different interaction of silver with the two glasses matrix,which leads to a different nucleation rate of the Ag clusters.
基金financially supported in part by the National Key R&D Program of China (2017YFA0207301, and 2017YFA0403402)the National Natural Science Foundation of China (21725102, 91961106, U1832156, 22075267, 21803002, 91963108, 21950410514, and U1732272)+5 种基金CAS Key Research Program of Frontier Sciences (QYZDB-SSW-SLH018)Science and Technological Fund of Anhui Province for Outstanding Youth (2008085 J05)Youth Innovation Promotion Association of CAS (2019444)Young Elite Scientist Sponsorship Program by CAST, China Postdoctoral Science Foundation (2019 M652190, 2020 T130627)Chinese Universities Scientific Fund (WK2060190096), MOST (2018YFA0208603)DNL Cooperation Fund, CAS (DNL201922, DNL180201)
文摘Amidst the development of photoelectrochemical(PEC)CO_(2) conversion toward practical application,the production of high-value chemicals beyond C1 compounds under mild conditions is greatly desired yet challenging.Here,through rational PEC device design by combining Au-loaded and N-doped TiO_(2) plate nanoarray photoanode with Zn-doped Cu_(2)O dark cathode,efficient conversion of CO_(2) to CH3COOH has been achieved with an outstanding Faradaic efficiency up to 58.1%(91.5%carbon selectivity)at 0.5 V vs.Ag/AgCl.Temperature programmed desorption and in situ Raman spectra reveal that the Zn-dopant in Cu_(2)O plays multiple roles in selective catalytic CO_(2) conversion,including local electronic structure manipulation and active site modification,which together promote the formation of intermediate*CH2/*CH3 for C-C coupling.Apart from that,it is also unveiled that the sufficient electron density provided by the Au-loaded and N-doped TiO_(2) plate nanoarray photoanode plays an equally important role by initiating multi-electron CO_(2) reduction.This work provides fresh insights into the PEC system design to reach the multi-electron reduction reaction and facilitate the C-C coupling reaction toward high-value multicarbon(C2+)chemical production via CO_(2) conversion.
