Analysis of Effects of the Arc Voltage on Arc Discharges in a Cathode Ion Source of Neutral Beam Injector

A hot cathode bucket ion source is used for the EAST（experimental advanced superconducting tokamak）neutral beam injector.The thermal electrons emitted from the surface of the cathode are extracted and accelerated by the electric field formed by the arc voltage,which is applied between the arc chamber of the ion source and the cathode.This paper analyzes the effects of arc voltage on the arc discharge in a hot cathode high current ion source.

Engineering adjacent Fe_(3)C as proton-feeding centers to single Fe sites enabling boosted oxygen reduction reaction kinetics for robust Zn-air batteries at high current densities

Oxygen reduction reaction(ORR)plays an important role in the next-generation energy storage technologies,whereas it involves the sluggish and complicated proton-coupled electron transfer(PCET)steps that greatly limit the ORR kinetics.Therefore,it is urgent to construct an efficient catalyst that could simultaneously achieve the rapid oxygen-containing intermediates conversion and fast PCET process but remain challenging.Herein,the adjacent Fe_(3)C nanoparticles coupling with single Fe sites on the bubble-wrap-like porous N-doped carbon(Fe_(3)C@FeSA-NC)were deliberately constructed.Theoretical investigations reveal that the adjacent Fe_(3)C nanoparticles speed up the water dissociation and serve as proton-feeding centers for boosting the ORR kinetics of single Fe sites.Benefiting from the synergistic effect of the Fe_(3)C and single Fe sites,the Fe_(3)C@FeSA-NC affords an excellent half-wave potential of 0.88 V,and enables the assembled Zn-air batteries with the high peak power density of 164.5 mW·cm^(-2)and long-term stability of over 200 h at high current densities at 50 mA·cm^(-2).This work clarifies the mechanism for improving ORR kinetics of single atomic sites by engineering the adjacent proton-feeding centers,shedding light on the rational design of cost-effective electrocatalysts for energy conversion and storage technologies.

Study on electrochemical property of La_(0.75)Mg_(0.25)Ni_(2.85)Co_(0.45–x)(AlSn)_x (x=0.0,0.1,0.2,0.3) alloys

La_（0.75）Mg_（0.25）Ni_（2.85）Co_（0.45–x）（AlSn）_x（AlSn）_x（x=0.0,0.1,0.2,0.3） alloys were prepared by magnetic induction melting method, and the phase composition and electrochemical properties were investigated systematically. The alloys were mainly composed of LaNi5, La2Ni7 and LaNi3 phase, and the cell volume of LaNi5 increased with the Al and Sn contents. For the alloy corresponding to x=0.0, the Cmax and C150 were 348.9 and 185 mA h/g, respectively, then for the alloy electrode with x=0.2, even though the Cmax was only 309.0 mA h/g less than 348.9 mA h/g, the C150 of 231 mA h/g was much higher than 185 mA h/g. And the values of the limit current density, anodic peak current density and hydrogen diffusion coefficient of the La0.75Mg0.25Ni2.85Co0.35（AlS n）0.1（x=0.1） alloy were 1079.5, 1023.8 mA /g and 5.71×10–10 cm2/s, respectively. Which were the highest than that of any other electrodes. These results suggested that the kinetic property of the La_（0.75）Mg_（0.25）Ni_（2.85）Co_（0.45–x）（AlSn）_x（AlSn）_x（x=0.0, 0.1, 0.2, 0.3） electrodes could be improved effectively by adding moderate contents of Al and Sn.