In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary eq...In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary equilibrium code is developed to investigate such advanced tokamak discharges with current reversal equilibrium configuration. The calculation results show that the reversal current equilibrium can maintain finite pressure and also has considerable effects on the position of the X-point and the magnetic separatrix shape, and hence also on the position of the strike point on the divertor plates, which is extremely useful for magnetic design, MHD stability analysis, and experimental data analysis etc. for the AC plasma current operation on tokamaks.展开更多
Electrocatalytic water splitting,which is recognized as an ideal technology to tackle escalating energy demands and related environmental problems,has attracted growing interest.The sluggish dynamics of the oxygen evo...Electrocatalytic water splitting,which is recognized as an ideal technology to tackle escalating energy demands and related environmental problems,has attracted growing interest.The sluggish dynamics of the oxygen evolution reaction(OER)has posed an intractable problem in this regard,hindering the practical commercial application of hydrogen production via water splitting.Therefore,the development of active and stable electrocatalysts is a prerequisite for accelerating OER kinetics,which greatly relies on the mechanistic understanding of the structural-property relationship.Owing to the harsh anodic oxidation conditions,most of the catalysts undergo surface reconstruction during the OER process,which means the authentic active sites are the in-situ reconstructed species rather than the freshly prepared one.In this regard,fully comprehending the surface reconstruction process will help us to determine the active sites on the catalyst surface and gain insights into the design principles for more efficient OER catalysts.In this review,we will first give a summary of surface reconstruction of OER electrocatalysts.Then we will focus on the factors that affect surface reconstruction,in-situ/operando characterization technologies,and the strategies to govern surface reconstruction.In addition,we outline existing challenges and the outlook for the development of OER catalysts by tuning surface reconstruction.展开更多
The development of cost-effective,robust,and durable electrocatalysts to replace the expensive Pt-based catalysts towards oxygen reduction reaction(ORR)is the trending frontier research topic in renewable energy and e...The development of cost-effective,robust,and durable electrocatalysts to replace the expensive Pt-based catalysts towards oxygen reduction reaction(ORR)is the trending frontier research topic in renewable energy and electrocatalysis.Particular attention has been paid to metal-nitrogen-carbon(M-N-C)single atom catalysts(SACs)due to their maximized atom utilization efficiency,biomimetic active site,and distinct electronic structure.More importantly,their catalytic properties can be further tailored by rationally regulating the microenvironment of active sites(i.e.,M-N coordination number,heteroatom doping and substitution.Herein,we present a comprehensive summary of the recent advancement in the microenvironment regulation of MN-C SACs towards improved ORR performance.The coordination environment manipulation regarding central metal and coordinated atoms is first discussed,focusing on the structure-function relationship.Apart from the near-range coordination,longrange substrate modulation including heteroatom doping,defect engineering is discussed as well.Besides,the synergy mechanism of nanoparticles and single atom sites to tune the electron cloud density at the active sites is summarized.Finally,we provide the challenges and outlook of the development of M-N-C SACs.展开更多
基金supported by National Natural Science Foundation of China (No. 12075276)partly by the Comprehensive Research Facility for Fusion Technology Program of China (No. 2018000052-73-01-001228)。
文摘In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary equilibrium code is developed to investigate such advanced tokamak discharges with current reversal equilibrium configuration. The calculation results show that the reversal current equilibrium can maintain finite pressure and also has considerable effects on the position of the X-point and the magnetic separatrix shape, and hence also on the position of the strike point on the divertor plates, which is extremely useful for magnetic design, MHD stability analysis, and experimental data analysis etc. for the AC plasma current operation on tokamaks.
基金financially supported by the National Nature Science Foundation of China(grant no.22279129)the Jilin Province Science and Technology Development Program(grant nos.20230101367JC and 20230201154GX).
文摘Electrocatalytic water splitting,which is recognized as an ideal technology to tackle escalating energy demands and related environmental problems,has attracted growing interest.The sluggish dynamics of the oxygen evolution reaction(OER)has posed an intractable problem in this regard,hindering the practical commercial application of hydrogen production via water splitting.Therefore,the development of active and stable electrocatalysts is a prerequisite for accelerating OER kinetics,which greatly relies on the mechanistic understanding of the structural-property relationship.Owing to the harsh anodic oxidation conditions,most of the catalysts undergo surface reconstruction during the OER process,which means the authentic active sites are the in-situ reconstructed species rather than the freshly prepared one.In this regard,fully comprehending the surface reconstruction process will help us to determine the active sites on the catalyst surface and gain insights into the design principles for more efficient OER catalysts.In this review,we will first give a summary of surface reconstruction of OER electrocatalysts.Then we will focus on the factors that affect surface reconstruction,in-situ/operando characterization technologies,and the strategies to govern surface reconstruction.In addition,we outline existing challenges and the outlook for the development of OER catalysts by tuning surface reconstruction.
基金supported by the National Natural Science Foundation of China(No.22272161).
文摘The development of cost-effective,robust,and durable electrocatalysts to replace the expensive Pt-based catalysts towards oxygen reduction reaction(ORR)is the trending frontier research topic in renewable energy and electrocatalysis.Particular attention has been paid to metal-nitrogen-carbon(M-N-C)single atom catalysts(SACs)due to their maximized atom utilization efficiency,biomimetic active site,and distinct electronic structure.More importantly,their catalytic properties can be further tailored by rationally regulating the microenvironment of active sites(i.e.,M-N coordination number,heteroatom doping and substitution.Herein,we present a comprehensive summary of the recent advancement in the microenvironment regulation of MN-C SACs towards improved ORR performance.The coordination environment manipulation regarding central metal and coordinated atoms is first discussed,focusing on the structure-function relationship.Apart from the near-range coordination,longrange substrate modulation including heteroatom doping,defect engineering is discussed as well.Besides,the synergy mechanism of nanoparticles and single atom sites to tune the electron cloud density at the active sites is summarized.Finally,we provide the challenges and outlook of the development of M-N-C SACs.
