摘要：Efficient and economical electrocatalysts should be developed for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)to split water for an extensive application prospect of green and clean hydrogen ***,we develop highly efficient OER and HER electrocatalysts through the scalable fabrication of Ni Fe Zn hydroxide nanosheets firmly arrayed on a hierarchical porous intermetallic Ni Zn and Ni heterojunction over nickel foam(Ni Fe Zn-OH/Ni Zn-Ni/NF).One bimodal porous Ni Zn intermetallic/Ni layer is in situ constructed on the nickel foam surface to maximize the exposure of catalytic sites and build firm Ni Fe Zn-OH nanosheets via the redox reaction with Fe Cl;.Ni Fe Zn-OH/Ni Zn-Ni/NF shows low overpotentials of?50/600 around 235/284 m V for OER and?50/600 around73/212 m V for HER,small Tafel slopes of 46.1 and41.1 m V dec^(-1),and prolonged catalytic durability in an alkaline medium because of the strong synergistic effects of Zn doping,multiple interface engineering,and integral threedimensional free-standing *** bifunctional catalysts,Ni Fe Zn-OH/Ni Zn-Ni/NF required a low electrolytic voltage of1.49 V at 20 m A cm^(-2)(1.61 V at 100 m A cm^(-2))with a sustained and stable output for 40 h during water *** work might provide insights into the exploration of low-cost and highly efficient intermetallic/multimetallic hydroxide heterostructured electrocatalysts for practical overall water splitting.

摘要：Interfacial space charge storage between ionic and electronic conductor is a promising scheme to further improve energy and power density of alkali metal ion batteries(AMIBs).However,the general behavior of space charge storage in AMIBs has been less investigated experimentally,mostly due to the complicated electrochemical behavior and lack of proper characterization ***,we use operando magnetometry to verify that in FeSe_(2)AMIBs,abundant Li^(+)/Na^(+)/K^(+)(M^(+))can be stored at M_(2)Se phase while electrons accumulate at Fe nanoparticles,forming interfacial space charge *** and dynamics tests further demonstrate that with increasing ionic radius from Li^(+),Na^(+)to K^(+),the reaction kinetics can be hindered,resulting in limited Fe formation and reduced space charge storage *** work lays solid foundation for studying the complex interfacial effect in electrochemical processes and designing advanced energy storage devices with substantial capacity and considerable power density.