The NASICON-structured Na_(2)VTi(PO_(4))_(3)(NVTPO)has attracted significant attention due to its exceptional structural stability and rapid Na~+mobility.However,the development of this material has been hindered by p...The NASICON-structured Na_(2)VTi(PO_(4))_(3)(NVTPO)has attracted significant attention due to its exceptional structural stability and rapid Na~+mobility.However,the development of this material has been hindered by poor electronic conductivity and inadequate low-temperature performance.Herein,a feasible strategy of lattice regulation integrated with surface modification for NVTPO by nitrogen(N)deep doping is proposed.Systematic characterizations and theoretical calculations confirm that N is doped into both the inner crystal structure of NVTPO and the outer carbon layer.The blueshift of the P—O bonds and charge redistribution induced by the V/Ti—N bonds strengthen the local environment and narrow the bandgap,thereby enabling reversible structural evolution and improving electronic conductivity.As expected,the optimized NVTPO/N@CN material achieves an ultra-high capacity of 188.48 mA h g^(-1)at 10 mA g^(-1)and a long-term lifespan of 2000 cycles at 1 A g^(-1).More importantly,it exhibits competitive low-temperature performance(92.15%retention after 1000 cycles at 300 mA g^(-1)and-15℃)due to reduced charge transfer impedance and activation energy.This deep doping strategy modification is expected to broaden the applications of NASICON-type cathodes.展开更多
V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for N...V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.展开更多
基金supported by the National Natural Science Foundation of China(22272205 and 22178094)the Hunan Provincial Nature Science Foundation of China(2022JJ30685,2023JJ20059 and 2024JJ5292)+2 种基金the Hunan Provincial Science and Technology Plan Projects of China(2022RC3050 and 2017TP1001)the financial support from the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Provincesupport from the Young Elite Scientists Sponsorship Program by CAST(YESS20220432)。
文摘The NASICON-structured Na_(2)VTi(PO_(4))_(3)(NVTPO)has attracted significant attention due to its exceptional structural stability and rapid Na~+mobility.However,the development of this material has been hindered by poor electronic conductivity and inadequate low-temperature performance.Herein,a feasible strategy of lattice regulation integrated with surface modification for NVTPO by nitrogen(N)deep doping is proposed.Systematic characterizations and theoretical calculations confirm that N is doped into both the inner crystal structure of NVTPO and the outer carbon layer.The blueshift of the P—O bonds and charge redistribution induced by the V/Ti—N bonds strengthen the local environment and narrow the bandgap,thereby enabling reversible structural evolution and improving electronic conductivity.As expected,the optimized NVTPO/N@CN material achieves an ultra-high capacity of 188.48 mA h g^(-1)at 10 mA g^(-1)and a long-term lifespan of 2000 cycles at 1 A g^(-1).More importantly,it exhibits competitive low-temperature performance(92.15%retention after 1000 cycles at 300 mA g^(-1)and-15℃)due to reduced charge transfer impedance and activation energy.This deep doping strategy modification is expected to broaden the applications of NASICON-type cathodes.
基金Supported by Fundamental Research Funds for Central Universities(HEUCF201403002)Advanced Technique Project Funds of the Manufacture and Information Ministry
基金supported by the National Natural Science Foundation of China (51372137)the National High Technology Research and Development Program of China (863 Program,2015AA034603)~~
文摘V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.
