Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loadin...Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.展开更多
Linearly bonded triiodide chains with fairly small distance between the adjacent iodine ions feature a facile electron transfer and highly anisotropic properties.Here,we demonstrate a novel strategy towards a new one-...Linearly bonded triiodide chains with fairly small distance between the adjacent iodine ions feature a facile electron transfer and highly anisotropic properties.Here,we demonstrate a novel strategy towards a new one-dimensional linear triiodide DMEDA·I6,using chain-type N,N'-dimethylethanediamine(DMEDA)cation to coordinate triiodine ions.This triiodide has the shortest distance between adjacent I3^- and good linearity.An estimated electronic band gap of1.36 e V indicates its semiconducting properties.100 fold differences both in polarization-sensitive absorption and effective mass were achieved by simulation,with directions parallel and perpendicular to the a-axis of DMEDA·I6.The DMEDA·I6 single crystal-based photodetectors show a good switching characteristic and a distinct polarization-sensitive photoresponse with linear dichroic photodetection ratio of about 1.9.Strongly anisotropic features and semiconducting properties of DMEDA·I6 make this triiodide system an interesting candidate for polarization related applications.展开更多
The dynamic first hyperpolarizabilities of a series of 1,10-phenanthroline Ru（II） complexes were carried out using density functional theory （DFT）. The results indicate that these complexes have large second-order...The dynamic first hyperpolarizabilities of a series of 1,10-phenanthroline Ru（II） complexes were carried out using density functional theory （DFT）. The results indicate that these complexes have large second-order nonlinear optical （NLO） responses. Specially, complex 6b has a maximal first hyperpolarizability βtot value. The first hyperpolarizabilities can be tuned by changing the ancillary ligand, introducing electron-acceptor group NO2 and/or increasing r-conjugation on phenanthroline. Calculations on absorption spectra demonstrate that the second-order NLO responses of complexes in series a are ascribed to the intraligand charge transfer （ILCT）, while the complexes in series b exhibit metal-to-ligand charge transfer （MLCT） and lig- and-to-ligand charge transfer （LLCT） transition at relatively low-energy absorptions.展开更多
Developing efficient counter electrodes(CEs)and quantum dots made of earth-abundant and non-toxic elements is essential but still challenging for quantum dot-sensitized solar cells(QDSSCs).Here,we report a facile stra...Developing efficient counter electrodes(CEs)and quantum dots made of earth-abundant and non-toxic elements is essential but still challenging for quantum dot-sensitized solar cells(QDSSCs).Here,we report a facile strategy to prepare self-supported and robust CoS_2and NiS nanocrystals-assembled nanosheets directly grown on carbon paper(MS_xNS@CP)as efficient counter electrodes for QDSSCs.Such CEs integrate the merits of fast electron transfer from interconnected conductive scaffold,efficient mass transfer from hierarchically vertical nanosheet on 3D open substrate,as well as abundant highly active catalytic sites from metal sulphide nanocrystal units.As a result,QDDSCs based on such CoS_2NS@CP and NiS NS@CP CEs achieve a PCE of8.88%and 7.53%,respectively.The detailed analyses suggest that CoS_2NS@CP has the highest catalytic activity and shows the lowest charger transfer resistance,leading to the highest PCE.These findings may inspire the design and exploration of other self-supported efficient CEs by integrating highly active catalysts onto 3D conductive networks for efficient QDSSCs.展开更多
文摘Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.
基金financially supported by the National Natural Science Foundation of China (51761145048, 61725401 and 61704097)the Innovation Fund of WNLO and the 62th China Postdoctoral Science Foundation (2017M622418)
文摘Linearly bonded triiodide chains with fairly small distance between the adjacent iodine ions feature a facile electron transfer and highly anisotropic properties.Here,we demonstrate a novel strategy towards a new one-dimensional linear triiodide DMEDA·I6,using chain-type N,N'-dimethylethanediamine(DMEDA)cation to coordinate triiodine ions.This triiodide has the shortest distance between adjacent I3^- and good linearity.An estimated electronic band gap of1.36 e V indicates its semiconducting properties.100 fold differences both in polarization-sensitive absorption and effective mass were achieved by simulation,with directions parallel and perpendicular to the a-axis of DMEDA·I6.The DMEDA·I6 single crystal-based photodetectors show a good switching characteristic and a distinct polarization-sensitive photoresponse with linear dichroic photodetection ratio of about 1.9.Strongly anisotropic features and semiconducting properties of DMEDA·I6 make this triiodide system an interesting candidate for polarization related applications.
基金supported by the National Natural Science Foundation of China (20873017)the Natural Science Foundation of Jilin Province (20101154)
文摘The dynamic first hyperpolarizabilities of a series of 1,10-phenanthroline Ru（II） complexes were carried out using density functional theory （DFT）. The results indicate that these complexes have large second-order nonlinear optical （NLO） responses. Specially, complex 6b has a maximal first hyperpolarizability βtot value. The first hyperpolarizabilities can be tuned by changing the ancillary ligand, introducing electron-acceptor group NO2 and/or increasing r-conjugation on phenanthroline. Calculations on absorption spectra demonstrate that the second-order NLO responses of complexes in series a are ascribed to the intraligand charge transfer （ILCT）, while the complexes in series b exhibit metal-to-ligand charge transfer （MLCT） and lig- and-to-ligand charge transfer （LLCT） transition at relatively low-energy absorptions.
基金supported by the National Natural Science Foundation of China (21573249, 51732004)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12020100)
文摘Developing efficient counter electrodes(CEs)and quantum dots made of earth-abundant and non-toxic elements is essential but still challenging for quantum dot-sensitized solar cells(QDSSCs).Here,we report a facile strategy to prepare self-supported and robust CoS_2and NiS nanocrystals-assembled nanosheets directly grown on carbon paper(MS_xNS@CP)as efficient counter electrodes for QDSSCs.Such CEs integrate the merits of fast electron transfer from interconnected conductive scaffold,efficient mass transfer from hierarchically vertical nanosheet on 3D open substrate,as well as abundant highly active catalytic sites from metal sulphide nanocrystal units.As a result,QDDSCs based on such CoS_2NS@CP and NiS NS@CP CEs achieve a PCE of8.88%and 7.53%,respectively.The detailed analyses suggest that CoS_2NS@CP has the highest catalytic activity and shows the lowest charger transfer resistance,leading to the highest PCE.These findings may inspire the design and exploration of other self-supported efficient CEs by integrating highly active catalysts onto 3D conductive networks for efficient QDSSCs.
