A novel approach of decorating graphene surface with graphene quantum dots(abbreviated as GQDs@Gr)was presented to achieve superior tribological properties in Gr/Cu composites.The prepared GQDs@Gr hybrid reinforcement...A novel approach of decorating graphene surface with graphene quantum dots(abbreviated as GQDs@Gr)was presented to achieve superior tribological properties in Gr/Cu composites.The prepared GQDs@Gr hybrid reinforcement possessed superior dispersion and had achieved strong interface bonding with Cu matrix.GQDs@Gr/Cu composite showed a good combination of wear resistance and electrical conductivity due to the synergistic effect of GQDs and Gr.Specifically,the coefficient of friction(COF)was reduced to 0.3,the wear rate(WR)was 2.13×10^(-5) mm^(3)·N^(−1)·m^(−1)(only a quarter of pure copper),and maintained the electrical conductivity of 96.5%IACS(international annealed copper standard).As a result,delamination,fracture,and plow furrows on the wear surface of Gr/Cu composite indicate that fatigue and abrasive adhesive wear are the main wear mechanisms.Wear surface lubrication film and strong interface bonding ensure better comprehensive performance of GQDs@Gr/Cu composite.展开更多
The NO gas is easily oxidized to form toxic by-products(NO_(2))during the oxidation process,which are adsorbed on the catalyst surface and inhibit the subsequent reaction.For photocatalytic NO removal,a significant ch...The NO gas is easily oxidized to form toxic by-products(NO_(2))during the oxidation process,which are adsorbed on the catalyst surface and inhibit the subsequent reaction.For photocatalytic NO removal,a significant challenge is to achieve catalytic stability while maintaining high conversion efficiency.Here,we fabricated a(BiO)_(2)CO_(3)/β-Bi_(2)O_(3)heterostructure that enables efficient charge transfer and promotes the NO removal.We propose that the catalytic stability depends on the heterojunction structure,which is able to generate interfacial charge transfer channels.In addition,we further introduce graphene quantum dots on the heterojunction structure,which further strengthens the interfacial charge transfer dynamics and finally realizes that the NO_(2)byproduct could gain electrons and convert to the final product(nitrite or nitrate).This composite structure not only exhibits high activity for NO removal but also maintains long-term stability under visible light.展开更多
The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength ...The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength in metal matrix composites. In this study, citric acid was employed as the precursor for synthesizing multiscale carbon nanomaterials(graphene quantum dots and graphene, abbreviated as GQDs and GN). The GQDs@GN/Cu composites were fabricated through a segmented ball milling process in conjunction with subsequent spark plasma sintering(SPS). The intragranular GQDs and intergranular GQDs@GN had synergistically reinforced Cu composites through Orowan strengthening, load transfer strengthening and refinement strengthening. Furthermore,the robust interface bonding between GQDs@GN and Cu effectively mitigated interfacial impedance stemming from electron-boundary scattering. The yield strength and ultimate tensile strength of the GQDs@GN/Cu composites were recorded as 270 and 314 MPa, respectively, representing an improvement of 92 and 28% over pure Cu, while maintaining electrical conductivity at a level comparable to that of pure Cu. This study advances the understanding of the possibility of realizing a synergistic compatibility between electrical conductivity and mechanical strength in Cu composites.展开更多
Hydrogen production via seawater electrolysis,leveraging sustainable energy sources such as offshore wind or solar energy,has immense application potential.However,the abundance of chloride ions(Cl^(-))in seawater lea...Hydrogen production via seawater electrolysis,leveraging sustainable energy sources such as offshore wind or solar energy,has immense application potential.However,the abundance of chloride ions(Cl^(-))in seawater leads to the generation of chlorine gas and hypochlorite at the anode during electrolysis,pos-ing a severe threat of corrosion of the catalyst and electrolytic equipment.Herein,we synthesize a NiMo-based catalyst adorned with surface-anchored graphene quantum dots(GQDs).This catalyst possesses ex-cellent Cl^(-)exclusion capabilities.The Mo-NiS/Se@GQDs core-shell nanorod catalyst requires only 170 mV of overpotential to attain a current density of 10 mA cm^(-2) and operates stably for 200 h without degra-dation across a broad current density range from 100 to 400 mA cm^(-2).This remarkable electrocatalytic stability arises from the dynamic and efficient repulsion of Cl^(-)at the catalytic interface,as proven by the post-reaction analysis of Cl^(-)distribution within the catalyst.Furthermore,a potentiodynamic polarization test revealed that the Mo-NiS/Se@GQDs catalyst has high corrosion potential(0.66 V)and low corrosion current density(122.93μA cm^(-2)),underscoring its excellent corrosion resistance.This research presents a novel approach to mitigate Cl^(-)corrosion during hydrogen production through seawater electrolysis,laying a solid foundation for advancing sustainable energy conversion technologies.展开更多
基金supported by Yunnan Fundamental Research Projects(No.202401CF070085)Yunnan Engineering Research Projects(No.2023-XMDJ-00617273)+1 种基金Industrial Support Plan Project of Gansu Provincial Education Department(No.2024CYZC-22)the National Natural Science Foundation of China(No.52064032).
文摘A novel approach of decorating graphene surface with graphene quantum dots(abbreviated as GQDs@Gr)was presented to achieve superior tribological properties in Gr/Cu composites.The prepared GQDs@Gr hybrid reinforcement possessed superior dispersion and had achieved strong interface bonding with Cu matrix.GQDs@Gr/Cu composite showed a good combination of wear resistance and electrical conductivity due to the synergistic effect of GQDs and Gr.Specifically,the coefficient of friction(COF)was reduced to 0.3,the wear rate(WR)was 2.13×10^(-5) mm^(3)·N^(−1)·m^(−1)(only a quarter of pure copper),and maintained the electrical conductivity of 96.5%IACS(international annealed copper standard).As a result,delamination,fracture,and plow furrows on the wear surface of Gr/Cu composite indicate that fatigue and abrasive adhesive wear are the main wear mechanisms.Wear surface lubrication film and strong interface bonding ensure better comprehensive performance of GQDs@Gr/Cu composite.
基金supported by the National Natural Science Foundation of China(Nos.22172019,52002054)the Sichuan Science and Technology Program(No.2022JDRC0084)。
文摘The NO gas is easily oxidized to form toxic by-products(NO_(2))during the oxidation process,which are adsorbed on the catalyst surface and inhibit the subsequent reaction.For photocatalytic NO removal,a significant challenge is to achieve catalytic stability while maintaining high conversion efficiency.Here,we fabricated a(BiO)_(2)CO_(3)/β-Bi_(2)O_(3)heterostructure that enables efficient charge transfer and promotes the NO removal.We propose that the catalytic stability depends on the heterojunction structure,which is able to generate interfacial charge transfer channels.In addition,we further introduce graphene quantum dots on the heterojunction structure,which further strengthens the interfacial charge transfer dynamics and finally realizes that the NO_(2)byproduct could gain electrons and convert to the final product(nitrite or nitrate).This composite structure not only exhibits high activity for NO removal but also maintains long-term stability under visible light.
基金financially supported by the National Natural Science Foundation of China (Nos.52174345 and 52064032)the Science and Technology Major Project of Yunnan Province (No.202202AG050004)。
文摘The configuration and quality of reinforcements, as well as the robustness of interfacial bonding,holding a critical significance in determining the concurrence between electrical conductivity and mechanical strength in metal matrix composites. In this study, citric acid was employed as the precursor for synthesizing multiscale carbon nanomaterials(graphene quantum dots and graphene, abbreviated as GQDs and GN). The GQDs@GN/Cu composites were fabricated through a segmented ball milling process in conjunction with subsequent spark plasma sintering(SPS). The intragranular GQDs and intergranular GQDs@GN had synergistically reinforced Cu composites through Orowan strengthening, load transfer strengthening and refinement strengthening. Furthermore,the robust interface bonding between GQDs@GN and Cu effectively mitigated interfacial impedance stemming from electron-boundary scattering. The yield strength and ultimate tensile strength of the GQDs@GN/Cu composites were recorded as 270 and 314 MPa, respectively, representing an improvement of 92 and 28% over pure Cu, while maintaining electrical conductivity at a level comparable to that of pure Cu. This study advances the understanding of the possibility of realizing a synergistic compatibility between electrical conductivity and mechanical strength in Cu composites.
基金financially supported by the National Natural Science Foundation of China(Nos.22103045 and 52273077)the State Key Laboratory of Bio-Fibers and Eco-Textiles,Qingdao University(Nos.ZDKT202108,RZ2000003334,and G2RC202022).
文摘Hydrogen production via seawater electrolysis,leveraging sustainable energy sources such as offshore wind or solar energy,has immense application potential.However,the abundance of chloride ions(Cl^(-))in seawater leads to the generation of chlorine gas and hypochlorite at the anode during electrolysis,pos-ing a severe threat of corrosion of the catalyst and electrolytic equipment.Herein,we synthesize a NiMo-based catalyst adorned with surface-anchored graphene quantum dots(GQDs).This catalyst possesses ex-cellent Cl^(-)exclusion capabilities.The Mo-NiS/Se@GQDs core-shell nanorod catalyst requires only 170 mV of overpotential to attain a current density of 10 mA cm^(-2) and operates stably for 200 h without degra-dation across a broad current density range from 100 to 400 mA cm^(-2).This remarkable electrocatalytic stability arises from the dynamic and efficient repulsion of Cl^(-)at the catalytic interface,as proven by the post-reaction analysis of Cl^(-)distribution within the catalyst.Furthermore,a potentiodynamic polarization test revealed that the Mo-NiS/Se@GQDs catalyst has high corrosion potential(0.66 V)and low corrosion current density(122.93μA cm^(-2)),underscoring its excellent corrosion resistance.This research presents a novel approach to mitigate Cl^(-)corrosion during hydrogen production through seawater electrolysis,laying a solid foundation for advancing sustainable energy conversion technologies.
