Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in tur...Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in turn, hampers light utilization efficiency. In this work, we report a novel heterojunction comprising alternating S-doped g-C_(3)N_(4) (SCN) and N-doped MoS_(2) (NMS), bridged by Mo–N covalent bonds within hierarchical periodic macroporous (HPM) walls. This heterojunction is synthesized by co-pyrolyzing dicyandiamide, thiourea, and ammonium molybdate. Transient reflectance photoluminescence measurements reveal that the Mo–N covalent bonds serve as “fast tracks” for electron transfer from SCN to NMS, significantly enhancing the charge separation efficiency. Additionally, the well-defined spatial separation of photo-induced carriers, coupled with the efficient mass transfer within the HPM structure, promotes superior carrier utilization. Thanks to the synergistic effect of HPM structures and the bridged Mo–N bonds, the optimized HPM NMS/SCN-1.3 sample exhibits a remarkable H_(2) evolution rate of 473.3 µmol g^(−1) h^(−1) under visible light irradiation, which is approximately 163 and 19 times higher than bulk g-C_(3)N_(4) (BCN) and HPM SCN, respectively. This work offers valuable insights into the design of HPM heterojunctions composed of co-catalysts and host catalysts, paving the way for enhanced photocatalytic H₂ evolution.展开更多
Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffus...Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffusion hinder its practical applications.Herein,a self-template and in situ vulcanization strategy is developed to synthesize self-supported hybrid nanotube arrays composed of nitrogen/sulfur-codoped carbon coated sulfur-doped TiO_2 nanotubes(S-TiO_2@NS-C) starting from H_2 Ti_2 O_5-H_2 O nanoarrays.The S-TiO_2@NS-C composite with one-dimensional nano-sized subunits integrates several merits.Specifically,sulfur doping strongly improves the Na~+ storage ability of TiO_2@C-N nanotubes by narrowing the bandgap of original TiO_2.Originating from the nanoarrays structures built from hollow nanotubes,carbon layer and sulfur doping,the sluggish Na~+ insertion/extraction kinetics is effectively improved and the volume variation of the electrode material is significantly alleviated.As a result,the S-TiO_2@NS-C nanoarrays present efficient sodium storage properties.The greatly improved sodium storage performances of S-TiO_2@NS-C nanoarrays confirm the importance of rational engineering and synthesis of hollow array architectures with higher complexity.展开更多
In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tr...In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.展开更多
Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their prac...Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their practical applications.Herein,FeSe_(2-x)S_(x)microspheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2 as both the Fe and S source,followed by gas phase selenization.The density functional theory calculation results reveal that S doping not only improves the Na adsorption,but also lower the diffusion energy barrier of Na atoms at the S doping sites,at the same time enhance the electronic conductivity of FeSe_(2-x)S_(x).The carbon-free nature of the FeSe_(2-x)S_(x)microspheres results in a low specific surface area and a high tap density,leading to an initial columbic efficiency of 85.6%.Compared with pure FeSe_(2),such FeSe_(2-x)S_(x)delivers a high reversible capacity of 373.6 mAh⋅g^(-1)at a high current density of 5 A⋅g^(-1)after 2000 cycles and an enhanced rate performance of 305.8 mAh⋅g^(-1)at even 50 A⋅g1.Finally,the FeSe_(2-x)S_(x)//NVP pouch cells have been assembled,achieving high energy and volumetric energy densities of 118 Wh⋅kg1 and 272 mWh⋅cm3,respectively,confirming the potential of applications for the FeSe_(2-x)S_(x)microspheres.展开更多
Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolu...Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolution reaction(HER)by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H*desorption.Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8-0.4 nm NPs present on TNT layers,and it emerges with the highest HER activity among all the electrodes synthesized.A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti^(3+)states and the coexistence of Ru SAs and NPs.With insights from literature,the role of Ti^(3+),appropriate work functions of TNT layers and Ru,and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified.The aforementioned characteristics led to a remarkable performance by having 9mV onset potentials and 33 mV dec^(-1) of Tafel slopes and a higher turnover frequency of 1.72 H2 s^(-1) at 30 mV.Besides,a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.展开更多
We prepared TiO 2(anatase) and Sn doped TiO 2 nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XRD and XPS experiments showed that Sn was doped into the lattice of TiO 2 with a ratio of ...We prepared TiO 2(anatase) and Sn doped TiO 2 nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XRD and XPS experiments showed that Sn was doped into the lattice of TiO 2 with a ratio of n (Sn)∶ n (Ti)=1∶10 . Sn doping largely enhanced the photocatalytic activity of TiO 2 film for phenol degradation. The enhancement in photoactivity by doping was discussed, based on the characterization with AFM, FTIR and EFISPS. Sn doping produced localized level of Sn 4+ in the band gap of TiO 2, about 0.4 eV below the conduction band, which could capture photogenerated electrons and reduce O 2 adsorbed on the surface of TiO 2 film, thus accelerated the photocatalytic reaction.展开更多
The transition metal ion doped TiO 2 nanoparticles were prepared with hydrothermal method, and the effects of doping different metal ions on the ability of TiO 2 in photocatalyzing degradation of rhodamine B(RB) were ...The transition metal ion doped TiO 2 nanoparticles were prepared with hydrothermal method, and the effects of doping different metal ions on the ability of TiO 2 in photocatalyzing degradation of rhodamine B(RB) were studied. The results showed that the doping of Fe 3+ , Co 2+ , Ni 2+ and Cr 3+ in TiO 2 nanoparticles made the photocatalytic efficiency of the TiO 2 particles reduce and the higher the initial content of Fe 3+ , the lower the ability of TiO 2 in photocatalyzing the degradation of RB. But the doping of Zn 2+ and Cd 2+ , especially Zn 2+ , made the photocatalytic efficiency of the TiO 2 particles enhance, showing a great increase of the rate constant( k ) and the initial reaction rate( r ini ).展开更多
基金support of the National Natural Science Foundation of China(Nos.52174238,22378103,52204307,and 22409128)Natural Science Foundation of Changsha(No.kq2208425)the Research Foundation Bureau of Hunan Province(No.24B0787).
文摘Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in turn, hampers light utilization efficiency. In this work, we report a novel heterojunction comprising alternating S-doped g-C_(3)N_(4) (SCN) and N-doped MoS_(2) (NMS), bridged by Mo–N covalent bonds within hierarchical periodic macroporous (HPM) walls. This heterojunction is synthesized by co-pyrolyzing dicyandiamide, thiourea, and ammonium molybdate. Transient reflectance photoluminescence measurements reveal that the Mo–N covalent bonds serve as “fast tracks” for electron transfer from SCN to NMS, significantly enhancing the charge separation efficiency. Additionally, the well-defined spatial separation of photo-induced carriers, coupled with the efficient mass transfer within the HPM structure, promotes superior carrier utilization. Thanks to the synergistic effect of HPM structures and the bridged Mo–N bonds, the optimized HPM NMS/SCN-1.3 sample exhibits a remarkable H_(2) evolution rate of 473.3 µmol g^(−1) h^(−1) under visible light irradiation, which is approximately 163 and 19 times higher than bulk g-C_(3)N_(4) (BCN) and HPM SCN, respectively. This work offers valuable insights into the design of HPM heterojunctions composed of co-catalysts and host catalysts, paving the way for enhanced photocatalytic H₂ evolution.
基金financial supports provided by the National Natural Science Foundation of China (21871164)the Taishan Scholar Project Foundation of Shandong Province (ts20190908, ts201511004)the Natural Science Foundation of Shandong Province (ZR2019MB024)。
文摘Titanium dioxide(TiO_2) has been investigated broadly as a stable,safe,and cheap anode material for sodium-ion batteries in recent years.However,the poor electronic conductivity and inherent sluggish sodium ion diffusion hinder its practical applications.Herein,a self-template and in situ vulcanization strategy is developed to synthesize self-supported hybrid nanotube arrays composed of nitrogen/sulfur-codoped carbon coated sulfur-doped TiO_2 nanotubes(S-TiO_2@NS-C) starting from H_2 Ti_2 O_5-H_2 O nanoarrays.The S-TiO_2@NS-C composite with one-dimensional nano-sized subunits integrates several merits.Specifically,sulfur doping strongly improves the Na~+ storage ability of TiO_2@C-N nanotubes by narrowing the bandgap of original TiO_2.Originating from the nanoarrays structures built from hollow nanotubes,carbon layer and sulfur doping,the sluggish Na~+ insertion/extraction kinetics is effectively improved and the volume variation of the electrode material is significantly alleviated.As a result,the S-TiO_2@NS-C nanoarrays present efficient sodium storage properties.The greatly improved sodium storage performances of S-TiO_2@NS-C nanoarrays confirm the importance of rational engineering and synthesis of hollow array architectures with higher complexity.
基金financially supported by the National Nature Science Foundation of China(Nos.51405199 and21301075)the Natural Science Foundation of Jiangsu Province(Nos.BK20140551 and BK20140562)+4 种基金the Postdoctoral Science Foundation of China(No.2014M561579)the Postdoctoral Science Foundation of Jiangsu Province(No.1401106C)the Opening Foundation of Jiangsu Province Material Tribology Key Laboratory(No.Kjsmcx201304)the Senior Intellectuals Fund of Jiangsu University(No.13JDG099)the Industry-Academy-Research Union Foundation of Jiangsu Province(No.BY2013065-05)
文摘In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.
基金supported by the National Key R&D Program of China(No.2021YFB2401900).
文摘Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity.However,sluggish Naþdiffusion and low electronic conductivity of selenides still hinder their practical applications.Herein,FeSe_(2-x)S_(x)microspheres have been prepared via a self-doping solvothermal method using NH4Fe(SO4)2 as both the Fe and S source,followed by gas phase selenization.The density functional theory calculation results reveal that S doping not only improves the Na adsorption,but also lower the diffusion energy barrier of Na atoms at the S doping sites,at the same time enhance the electronic conductivity of FeSe_(2-x)S_(x).The carbon-free nature of the FeSe_(2-x)S_(x)microspheres results in a low specific surface area and a high tap density,leading to an initial columbic efficiency of 85.6%.Compared with pure FeSe_(2),such FeSe_(2-x)S_(x)delivers a high reversible capacity of 373.6 mAh⋅g^(-1)at a high current density of 5 A⋅g^(-1)after 2000 cycles and an enhanced rate performance of 305.8 mAh⋅g^(-1)at even 50 A⋅g1.Finally,the FeSe_(2-x)S_(x)//NVP pouch cells have been assembled,achieving high energy and volumetric energy densities of 118 Wh⋅kg1 and 272 mWh⋅cm3,respectively,confirming the potential of applications for the FeSe_(2-x)S_(x)microspheres.
基金support from the European Union Horizon 2020 program(project HERMES,nr.952184)the Ministry of Education,Youth and Sports of the Czech Republic for supporting CEMNAT(LM2023037)+1 种基金Czech-NanoLab(LM2023051)infrastructures for providing ALD,SEM,EDX,XPS,TEM,and XRDCzech Science Foundation(project 23-08019X,EXPRO).
文摘Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolution reaction(HER)by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H*desorption.Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8-0.4 nm NPs present on TNT layers,and it emerges with the highest HER activity among all the electrodes synthesized.A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti^(3+)states and the coexistence of Ru SAs and NPs.With insights from literature,the role of Ti^(3+),appropriate work functions of TNT layers and Ru,and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified.The aforementioned characteristics led to a remarkable performance by having 9mV onset potentials and 33 mV dec^(-1) of Tafel slopes and a higher turnover frequency of 1.72 H2 s^(-1) at 30 mV.Besides,a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.
文摘We prepared TiO 2(anatase) and Sn doped TiO 2 nanoparticlate film by Plasma enhanced Chemical Vapor Deposition(PECVD) method. XRD and XPS experiments showed that Sn was doped into the lattice of TiO 2 with a ratio of n (Sn)∶ n (Ti)=1∶10 . Sn doping largely enhanced the photocatalytic activity of TiO 2 film for phenol degradation. The enhancement in photoactivity by doping was discussed, based on the characterization with AFM, FTIR and EFISPS. Sn doping produced localized level of Sn 4+ in the band gap of TiO 2, about 0.4 eV below the conduction band, which could capture photogenerated electrons and reduce O 2 adsorbed on the surface of TiO 2 film, thus accelerated the photocatalytic reaction.
文摘The transition metal ion doped TiO 2 nanoparticles were prepared with hydrothermal method, and the effects of doping different metal ions on the ability of TiO 2 in photocatalyzing degradation of rhodamine B(RB) were studied. The results showed that the doping of Fe 3+ , Co 2+ , Ni 2+ and Cr 3+ in TiO 2 nanoparticles made the photocatalytic efficiency of the TiO 2 particles reduce and the higher the initial content of Fe 3+ , the lower the ability of TiO 2 in photocatalyzing the degradation of RB. But the doping of Zn 2+ and Cd 2+ , especially Zn 2+ , made the photocatalytic efficiency of the TiO 2 particles enhance, showing a great increase of the rate constant( k ) and the initial reaction rate( r ini ).
