Design and development of advanced electrocatalysts with high performance and low Pt consumption are crucial for reducing the kinetic energy barrier of the cathode oxygen reduction reaction(ORR)and improving the effic...Design and development of advanced electrocatalysts with high performance and low Pt consumption are crucial for reducing the kinetic energy barrier of the cathode oxygen reduction reaction(ORR)and improving the efficiency of proton exchange membrane fuel cells(PEMFC).In this study,we demonstrate a Pb-modulated PtCo system for efficient ORR,in which the inclusion of Pb in ternary alloys induces dislocation defects due to the significant difference in atomic radius.Dislocation-PtCoPb was confirmed to exhibit significantly higher ORR activity and stability in acidic ORR.In practical PEMFC applications,it outperforms the corresponding commercial Pt/C with a mass activity of 0.58 A·mgPt^(-1),making it a promising alternative to state-of-the-art Pt-based catalysts.The combination of experimental results and density functional theory(DFT)calculations offers valuable atomic-level insights into the dislocation structures.Pb with a larger atomic radius is located in the lattice stretching region below the dislocation slip plane,forming a structure similar to a Cottrell atmosphere,which reduces the dislocation energy and puts the system in a lower energy state.The Cottrell atmosphere pins the dislocation structure and stabilizes the ternary alloy.By adjusting the amount of added Pb,a moderate level of dislocation density induces a tuned strain effect,thereby enhancing the electrocatalytic mechanism by optimizing the electronic structure of the alloy surface and the adsorption and desorption of oxygen species.This work provides valuable insights into the design and development of lattice dislocation defect structures to trigger strain effects for improving ORR performance.展开更多
Influences of topological defect and dislocation on conductivity behavior of charge carriers in external electromagnetic fields are studied. Particularly the quantum Hall effect is investigated in detail. It is found ...Influences of topological defect and dislocation on conductivity behavior of charge carriers in external electromagnetic fields are studied. Particularly the quantum Hall effect is investigated in detail. It is found that the nontrivial deformations of spacetime due to topological defect and dislocation produce an electric current at the leading order of perturbation theory. This current then induces a deformation on the Hall conductivity. The corrections on the Hall conductivity depend on the external electric fields, the size of the sample and the momentum of the particle.展开更多
基金support of the National Natural Science Funds of China(No.22278016).
文摘Design and development of advanced electrocatalysts with high performance and low Pt consumption are crucial for reducing the kinetic energy barrier of the cathode oxygen reduction reaction(ORR)and improving the efficiency of proton exchange membrane fuel cells(PEMFC).In this study,we demonstrate a Pb-modulated PtCo system for efficient ORR,in which the inclusion of Pb in ternary alloys induces dislocation defects due to the significant difference in atomic radius.Dislocation-PtCoPb was confirmed to exhibit significantly higher ORR activity and stability in acidic ORR.In practical PEMFC applications,it outperforms the corresponding commercial Pt/C with a mass activity of 0.58 A·mgPt^(-1),making it a promising alternative to state-of-the-art Pt-based catalysts.The combination of experimental results and density functional theory(DFT)calculations offers valuable atomic-level insights into the dislocation structures.Pb with a larger atomic radius is located in the lattice stretching region below the dislocation slip plane,forming a structure similar to a Cottrell atmosphere,which reduces the dislocation energy and puts the system in a lower energy state.The Cottrell atmosphere pins the dislocation structure and stabilizes the ternary alloy.By adjusting the amount of added Pb,a moderate level of dislocation density induces a tuned strain effect,thereby enhancing the electrocatalytic mechanism by optimizing the electronic structure of the alloy surface and the adsorption and desorption of oxygen species.This work provides valuable insights into the design and development of lattice dislocation defect structures to trigger strain effects for improving ORR performance.
基金Supported by the China Scholarship Council under Grant No 201207010002the Hanjiang Scholar Project of Shaanxi University of Technology+3 种基金the National Natural Science Foundation of China under Grant No 11147181the Scientific Research Project of Shaanxi Province under Grant Nos 2009K01-54 and 12JK0960the Startup Foundation of the University of Science and Technology of Chinathe Project of Knowledge Innovation Program of the Chinese Academy of Sciences
文摘Influences of topological defect and dislocation on conductivity behavior of charge carriers in external electromagnetic fields are studied. Particularly the quantum Hall effect is investigated in detail. It is found that the nontrivial deformations of spacetime due to topological defect and dislocation produce an electric current at the leading order of perturbation theory. This current then induces a deformation on the Hall conductivity. The corrections on the Hall conductivity depend on the external electric fields, the size of the sample and the momentum of the particle.
