Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(HER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded ...Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(HER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded as low-active HER catalysts,due to their inapposite hydrogen adsorption and water dissociation.Here,we report a detailed study on perovskite LaCoO_(3)epitaxial thin films as a model catalyst to significantly enhance the HER performance via an electrochemical activation process.As a result,the overpotential for the activation films to achieve a current density of 0.36 m A/cm^(2)is 238 m V,reduced by more than 200 m V in comparison with that of original samples.Structural characterization revealed the activation process dramatically increases the concentration of oxygen vacancies(Vo)on the surface of LaCoO_(3).We established the relationship between the electronic structure induced by Vo and the enhanced HER activity.Further theoretical calculations revealed that the Vo optimizes the hydrogen adsorption and dissociation of water on the surface of LaCoO_(3)thin films,thus improving the HER catalytic activity.This work may promote a deepened understanding of perovskite oxides for HER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.展开更多
By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating paramet...By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating parameters of the combined process. The process involved advantages and shortages of SBR and CW. Under normal temperature, the 3rd cycle (SBR’s operation cycle is 8 h: inflow for 1 h, limited aeration for 3 h, sediment for 1 h, outflow for 1 h, and idling for 2 h; CW’s hydraulic retention time (HRT) is 24.8 h and hydraulic loading is 24.5 m3/m2 d) was the best cyclic mode. The effluents can meet the standard GB/T18921-2002: "The reuse of urban recycling water: water quality standard for scenic environment use". In the 3rd cycle, the efficiency of CW was the maximum, and energy consumption of SBR was the minimum. Under the condition of low dissolved oxygen, the removing efficiency of chemical oxygen demand (COD) and ammonia was not affected obviously. Simultaneously, nitrification and denitrification phenomena occured and phosphorus was absorbed obviously.展开更多
Exploring anode materials with high energy and power density is one of the critical milestones in developing sodium-ion batteries/capacitors(SIBs/SICs).Here,the Mo and W-based bimetallic organic framework(Mo-W-MOF)wit...Exploring anode materials with high energy and power density is one of the critical milestones in developing sodium-ion batteries/capacitors(SIBs/SICs).Here,the Mo and W-based bimetallic organic framework(Mo-W-MOF)with core-shell structure is first formed by a facile strategy,followed by a selenization and carbonization strategy to finally prepare multileveled Mo WSe_(2)/WO_(3)/C anode materials with core-shell petal like curled nanosheet structure.Between the petal(MoSe_(2))-core(WO_(3))structure,the formation of WSe_(2)flakes by partial selenization on the surface of WO_(3)serves as a heterogeneous connection between MoSe_(2)and WO_(3).The enlarged layer distance(0.677 nm)between MoSe_(2)and WSe_(2)can facilitate the rapid transfer of Na+and electrons.The density functional theory(DFT)calculations verify that the Mo WSe_(2)/WO_(3)/C heterostructure performs excellent metallic properties.Ex-situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron microscopy(TEM)confirm the activation process from the initial insertion reaction to the later conversion reaction.Resultantly,when employed as the anode of SIBs,a remarkable capacity of 384.3 mA h g-1after 950 cycles at 10 A g^(-1)is performed.Furthermore,the SICs assembled with commercial activated carbon(AC)as the cathode exhibits a remarkable energy density of 81.86 W h kg^(-1)(at 190 W kg^(-1))and 72.83 W h kg^(-1)(at 3800 W kg^(-1)).The unique structural design and the reaction investigation of the electrode process can provide a reference for the development of transition metal chalcogenides anodes.展开更多
基金funding support by the National Natural Science Foundation of China(Grant No.21872116 and 22075232)the Mobility Program of the Sino-German Center for Research Promotion(Grant No.M-0377)the financial support by National Natural Science Foundation of China(Grant No.21991151,21991150,22021001)。
文摘Developing highly-active,earth-abundant non-precious-metal catalysts for hydrogen evolution reaction(HER)in alkaline solution would be beneficial to sustainable energy storage.Perovskite oxides are generally regarded as low-active HER catalysts,due to their inapposite hydrogen adsorption and water dissociation.Here,we report a detailed study on perovskite LaCoO_(3)epitaxial thin films as a model catalyst to significantly enhance the HER performance via an electrochemical activation process.As a result,the overpotential for the activation films to achieve a current density of 0.36 m A/cm^(2)is 238 m V,reduced by more than 200 m V in comparison with that of original samples.Structural characterization revealed the activation process dramatically increases the concentration of oxygen vacancies(Vo)on the surface of LaCoO_(3).We established the relationship between the electronic structure induced by Vo and the enhanced HER activity.Further theoretical calculations revealed that the Vo optimizes the hydrogen adsorption and dissociation of water on the surface of LaCoO_(3)thin films,thus improving the HER catalytic activity.This work may promote a deepened understanding of perovskite oxides for HER mechanism by Vo adjusting and a new avenue for designing highly active electrochemical catalysts in alkaline solution.
基金Funded by Sustainable Water Management Improves Tomorrow’s City’s Health (SWITCH018530)
文摘By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating parameters of the combined process. The process involved advantages and shortages of SBR and CW. Under normal temperature, the 3rd cycle (SBR’s operation cycle is 8 h: inflow for 1 h, limited aeration for 3 h, sediment for 1 h, outflow for 1 h, and idling for 2 h; CW’s hydraulic retention time (HRT) is 24.8 h and hydraulic loading is 24.5 m3/m2 d) was the best cyclic mode. The effluents can meet the standard GB/T18921-2002: "The reuse of urban recycling water: water quality standard for scenic environment use". In the 3rd cycle, the efficiency of CW was the maximum, and energy consumption of SBR was the minimum. Under the condition of low dissolved oxygen, the removing efficiency of chemical oxygen demand (COD) and ammonia was not affected obviously. Simultaneously, nitrification and denitrification phenomena occured and phosphorus was absorbed obviously.
基金supported by the National Natural Science Foundation of China(22008053,52002111)the Key Research and Development Program of Hebei Province(20310601D,205A4401D)the Ministry of Higher Education of Malaysia for the Fundamental Research Grant(FRGS/1/2018/STG02/UM/02/10)awarded to Woo Haw Jiunn and University of Malaya research grant(GPF 038B-2018)。
文摘Exploring anode materials with high energy and power density is one of the critical milestones in developing sodium-ion batteries/capacitors(SIBs/SICs).Here,the Mo and W-based bimetallic organic framework(Mo-W-MOF)with core-shell structure is first formed by a facile strategy,followed by a selenization and carbonization strategy to finally prepare multileveled Mo WSe_(2)/WO_(3)/C anode materials with core-shell petal like curled nanosheet structure.Between the petal(MoSe_(2))-core(WO_(3))structure,the formation of WSe_(2)flakes by partial selenization on the surface of WO_(3)serves as a heterogeneous connection between MoSe_(2)and WO_(3).The enlarged layer distance(0.677 nm)between MoSe_(2)and WSe_(2)can facilitate the rapid transfer of Na+and electrons.The density functional theory(DFT)calculations verify that the Mo WSe_(2)/WO_(3)/C heterostructure performs excellent metallic properties.Ex-situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron microscopy(TEM)confirm the activation process from the initial insertion reaction to the later conversion reaction.Resultantly,when employed as the anode of SIBs,a remarkable capacity of 384.3 mA h g-1after 950 cycles at 10 A g^(-1)is performed.Furthermore,the SICs assembled with commercial activated carbon(AC)as the cathode exhibits a remarkable energy density of 81.86 W h kg^(-1)(at 190 W kg^(-1))and 72.83 W h kg^(-1)(at 3800 W kg^(-1)).The unique structural design and the reaction investigation of the electrode process can provide a reference for the development of transition metal chalcogenides anodes.
