Ag3PO4/Ag/Ag2Mo2O7 composite photocatalyst was successfully prepared via an in situ precipitation method. The as-prepared Ag3PO4/Ag/Ag2Mo2O7 nanocomposite included Ag3PO4 nanoparticles （NPs） as well as Ag NPs assemb...Ag3PO4/Ag/Ag2Mo2O7 composite photocatalyst was successfully prepared via an in situ precipitation method. The as-prepared Ag3PO4/Ag/Ag2Mo2O7 nanocomposite included Ag3PO4 nanoparticles （NPs） as well as Ag NPs assembling on the surface of Ag2Mo2O7 nanowires. Under visible light irradiation （λ〉420 nm）, the Ag3PO4/Ag/Ag2Mo2O7 com- posite degraded rhodamine B （Rh B） efficiently and showed much higher photocatalytic efficiency than pure AgaPO4, Ag2Mo2O7, or Ag3PO4/Ag2Mo2O7. It was elucidated that the excellent photocatalytic performance of Ag3PO4/Ag/Ag2Mo2O7 for the degradation of Rh B under visible light could be ascribed to the high specific surface area, the extended absorption in the visible light region resulting from the Ag3PO4/Ag loading, and the effi- cient separation of photogenerated electrons and holes through the ternary heterostrucure composed of Ag3PO4, Ag and Ag2Mo2O7.展开更多
Herein,we demonstrate the synthesis of W and Ba co-doped La2Mo2O9(LBMWO)nanocrystalline powder by a sol-gel process.In all the compositions have general formulae La1.9Ba0.1Mo2-xWxO8.95(x=0-0.40).The crystal structure,...Herein,we demonstrate the synthesis of W and Ba co-doped La2Mo2O9(LBMWO)nanocrystalline powder by a sol-gel process.In all the compositions have general formulae La1.9Ba0.1Mo2-xWxO8.95(x=0-0.40).The crystal structure,microstructure and conductivity of LBMWO were characterized by X-ray diffraction,scanning electron microscopy and electrical impedance spectroscopy.In addition,the thermal and decomposition properties of the LBMWO gel were analyzed by differential scanning calorimetry-thermogravimetric.The results reveal that all LBMWO powders calcined at 700℃have a cubic structure;the average crystallite size is about 48 nm.The unit cell parameter of LBMWO powders increases with increase in W content.The as-synthesized nanocrystalline LBMWO samples exhibit excellent sinterability and a relatively lower sintering temperature of 900℃.A high relative density of-96%is achieved after sintering at 900℃which is in good agreeme nt with the re sults of the SEM.Moreover,W and Ba codoping suppresses the phase transition and effectively stabilizes theβ-phase at low temperature.At the same time,La1.9Ba0.1Mo1.85W0.15O8.95 exhibits high ionic conductivity,3.07 x 10^-2 S/cm at 800℃.It is therefore concluded that co-doping can improve the properties of La2MO2O9 electrolytes.展开更多
Dielectric relaxation method was employed to study the properties of oxygen ion diffusion and phase transition in the oxide-ion conductors （Lal-xLnx）2Mo209 （Ln=Nd, Gd, x=0.05-0.25）. Two dielectric loss peaks were ...Dielectric relaxation method was employed to study the properties of oxygen ion diffusion and phase transition in the oxide-ion conductors （Lal-xLnx）2Mo209 （Ln=Nd, Gd, x=0.05-0.25）. Two dielectric loss peaks were observed： peak Pd at about 600 K and peak P5 around 720 K. Peak Pd is a relaxational peak and associated with the short-range diffusion of oxygen ions, while peak P5 hardly changes its position and dramatically decreases in height with increasing frequency, exhibiting non-relaxational nature. With increasing Ln^3＋ concentration, the heights of peak Ph and Pd increase at first and then decrease after passing a maximum at 15% doping. It is suggested that peak P5 is related to the phase transition of a static disordered state to a dynamic disordered state in oxygen ions/vacancies distribution. It is found that the 15%Gd or 15%Nd doped La2Mo209 samples exhibit the highest conductivity in accordance with the highest height of peak Pd at this doping content.展开更多
Emerging as a new class of two-dimensional materials with atomically thin layers,MBenes have great potential for many important applications such as energy storage and electrocatalysis.Toward mitigating carbon footpri...Emerging as a new class of two-dimensional materials with atomically thin layers,MBenes have great potential for many important applications such as energy storage and electrocatalysis.Toward mitigating carbon footprint,there has been increasing interest in CO_(2)/CO conversion on MBenes,but mostly focused on C_(1) products.C^(2+) chemicals generally possess higher energy densities and wider applications than C_(1) counterparts.However,C–C coupling is technically challenging because of high energy requirement and currently few catalysts are suited for this process.Here,we explore electrochemical CO reduction reaction to C_(2) chemicals on Mo_(2)B_(2)O_(2) MBene via density-functional theory calculations.Remarkably,the most favorable CO–COH coupling is revealed to be a spontaneous and barrierless process,making Mo_(2)B_(2)O_(2) an efficient catalyst for C–C coupling.Among C_(1) and C_(2) chemicals,ethanol is predicted to be the primary product.Furthermore,by charge and bond analysis,it is unraveled that there exist significantly more unbonded electrons in the C atom of intermediate*COH than other C_(1) intermediates,which is responsible for the facile C–C coupling.From an atomic scale,this work provides microscopic insight into C–C coupling process and suggests Mo_(2)B_(2)O_(2) a promising catalyst for electrochemical CO reduction to C_(2) chemicals.展开更多
基金supported by the National Natural Science Foundation of China(No.21407059,No.21576112,No.21407064,and No.21607051)the Science Development Project of Jiangsu Province(BK20140527)+1 种基金the Science and Technology Research Project of the Department of Education of Jilin Province(No.2015220)the Open Subject of the State Key Laboratory of Rare Earth Resource Utilization(RERU2017011)
文摘Ag3PO4/Ag/Ag2Mo2O7 composite photocatalyst was successfully prepared via an in situ precipitation method. The as-prepared Ag3PO4/Ag/Ag2Mo2O7 nanocomposite included Ag3PO4 nanoparticles （NPs） as well as Ag NPs assembling on the surface of Ag2Mo2O7 nanowires. Under visible light irradiation （λ〉420 nm）, the Ag3PO4/Ag/Ag2Mo2O7 com- posite degraded rhodamine B （Rh B） efficiently and showed much higher photocatalytic efficiency than pure AgaPO4, Ag2Mo2O7, or Ag3PO4/Ag2Mo2O7. It was elucidated that the excellent photocatalytic performance of Ag3PO4/Ag/Ag2Mo2O7 for the degradation of Rh B under visible light could be ascribed to the high specific surface area, the extended absorption in the visible light region resulting from the Ag3PO4/Ag loading, and the effi- cient separation of photogenerated electrons and holes through the ternary heterostrucure composed of Ag3PO4, Ag and Ag2Mo2O7.
基金Project supported by the Natural Science Foundation of Anhui Province of China(1708085ME112)Anhui Province Outstanding Young Teachers Visit Abroad Training Projects(gxfxZD2016220)+2 种基金Key Projects of Natural Science Research in Anhui Universities(KJ2018A0549,KJ2017A533)Major Project of Research and Development fund of Hefei University(17ZR02ZDA)the Graduate Thesis Innovative Foundation of Hefei University(CX201805)
文摘Herein,we demonstrate the synthesis of W and Ba co-doped La2Mo2O9(LBMWO)nanocrystalline powder by a sol-gel process.In all the compositions have general formulae La1.9Ba0.1Mo2-xWxO8.95(x=0-0.40).The crystal structure,microstructure and conductivity of LBMWO were characterized by X-ray diffraction,scanning electron microscopy and electrical impedance spectroscopy.In addition,the thermal and decomposition properties of the LBMWO gel were analyzed by differential scanning calorimetry-thermogravimetric.The results reveal that all LBMWO powders calcined at 700℃have a cubic structure;the average crystallite size is about 48 nm.The unit cell parameter of LBMWO powders increases with increase in W content.The as-synthesized nanocrystalline LBMWO samples exhibit excellent sinterability and a relatively lower sintering temperature of 900℃.A high relative density of-96%is achieved after sintering at 900℃which is in good agreeme nt with the re sults of the SEM.Moreover,W and Ba codoping suppresses the phase transition and effectively stabilizes theβ-phase at low temperature.At the same time,La1.9Ba0.1Mo1.85W0.15O8.95 exhibits high ionic conductivity,3.07 x 10^-2 S/cm at 800℃.It is therefore concluded that co-doping can improve the properties of La2MO2O9 electrolytes.
基金This work was supported by the Ningbo Civic Natural Science Foundation （No.2006A610057）, the Ningbo Civic Project of International Cooperation （No.2006B100080）, Zhejiang Provincial Project of International Cooperation （No.2007C24022）, and the National Natural Science Foundation of China （No.50672100 and No.50702061）.
文摘Dielectric relaxation method was employed to study the properties of oxygen ion diffusion and phase transition in the oxide-ion conductors （Lal-xLnx）2Mo209 （Ln=Nd, Gd, x=0.05-0.25）. Two dielectric loss peaks were observed： peak Pd at about 600 K and peak P5 around 720 K. Peak Pd is a relaxational peak and associated with the short-range diffusion of oxygen ions, while peak P5 hardly changes its position and dramatically decreases in height with increasing frequency, exhibiting non-relaxational nature. With increasing Ln^3＋ concentration, the heights of peak Ph and Pd increase at first and then decrease after passing a maximum at 15% doping. It is suggested that peak P5 is related to the phase transition of a static disordered state to a dynamic disordered state in oxygen ions/vacancies distribution. It is found that the 15%Gd or 15%Nd doped La2Mo209 samples exhibit the highest conductivity in accordance with the highest height of peak Pd at this doping content.
基金the A*STAR LCER-FI project(LCERFI01-0033 U2102d2006)the Ministry of Education of Singapore and the National University of Singapore(C-261-000-207-532/C-261-000-777-532 and R-279-000-574-114)for financial support.
文摘Emerging as a new class of two-dimensional materials with atomically thin layers,MBenes have great potential for many important applications such as energy storage and electrocatalysis.Toward mitigating carbon footprint,there has been increasing interest in CO_(2)/CO conversion on MBenes,but mostly focused on C_(1) products.C^(2+) chemicals generally possess higher energy densities and wider applications than C_(1) counterparts.However,C–C coupling is technically challenging because of high energy requirement and currently few catalysts are suited for this process.Here,we explore electrochemical CO reduction reaction to C_(2) chemicals on Mo_(2)B_(2)O_(2) MBene via density-functional theory calculations.Remarkably,the most favorable CO–COH coupling is revealed to be a spontaneous and barrierless process,making Mo_(2)B_(2)O_(2) an efficient catalyst for C–C coupling.Among C_(1) and C_(2) chemicals,ethanol is predicted to be the primary product.Furthermore,by charge and bond analysis,it is unraveled that there exist significantly more unbonded electrons in the C atom of intermediate*COH than other C_(1) intermediates,which is responsible for the facile C–C coupling.From an atomic scale,this work provides microscopic insight into C–C coupling process and suggests Mo_(2)B_(2)O_(2) a promising catalyst for electrochemical CO reduction to C_(2) chemicals.
