Doping-driven dual heterogeneous interfacial structures boosting the durability of industry-compatible water splitting at high current density

Developing highly stable electrocatalysts under industry-compatible current densities(>500 mA cm^(-2))in an anion-exchange membrane water electrolyzer(AEMWE)is an enormous challenge for water splitting.Herein,based on the results of density function theory calculations,a dual heterogeneous interfacial structured NiSe/Fe-Ni(OH)_(2)catalyst was subtly designed and successfully prepared by electrodepositing Fe-doped Ni(OH)_(2)on NiSe-loaded nickel foam(NF).Fe doping-driven heterogeneous structures in NiSe/Fe-Ni(OH)_(2)markedly boost catalytic activity and durability at industrially compatible current densities in single hydrogen and oxygen evolution reactions under alkaline conditions.In particular,NiSe/Fe-Ni(OH)_(2)shows a negligible performance loss at 600 mA cm^(-2)at least 1,000 h for overall water splitting,a distinguished long-term durability acting as AEMWE electrodes at 600 mA cm^(-2)and 1 A cm^(-2)at 85℃for at least 95 h.Owing to Fe doping-induced strong synergetic effect between Ni and Fe,dual heterostructure-promoted charge transfer and redistribution,abundant catalytic active sites,and improvement of stability and durability,a mechanism of Fe doping-driven heterogeneous interfacial structurepromoted catalytic performance was proposed.This study provides a successful example of theory-directed catalyst preparation and pioneers a creative strategy for industry-compatible water splitting at high current density.

Enhancing an internal electric field by a solid solution strategy for steering bulk-charge flow and boosting photocatalytic activity of Bi_(24)O_(31)Cl_(x)Br_(10-x)

Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community;however,a deeper understanding of the intrinsic origin for improved bulk-charge separation is still unclear.Herein,a series of Bi_(24)O_(31)Cl_(x)Br_(10-x) solid solutions with the same structural characteristics were synthesized by crystal structure regulation.Combining density functional theory calculation,Kelvin probe force microscopy,and zeta potential testing results,an enhanced internal electric field(IEF)intensity between[Bi_(24)O_(31)]and[X]layers was achieved by changing halogen types and ratios.This greatly facilitated bulk-charge separation and transfer efficiency,which is significant for the degradation of phenolic organic pollutants.Owing to the enhanced IEF intensity,the charge carrier density of Bi_(24)O_(31)Cl_(4)Br_(6) was 33.1 and 4.7 times stronger than that of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Therefore,Bi24O31Cl4Br6 had an optimal photoactivity for the degradation of bisphenol A,which was 6.21 and 2.71 times higher than those of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Thus,this study revealed the intrinsic mechanism of the solid solution strategy for photocatalytic performance enhancement with respect to an IEF.

Selenium vacancies regulate d-band centers in Ni_(3)Se_(4)toward paired electrolysis in anion-exchange membrane electrolyzers for upgrading N-containing compounds

Paired electrolysis in anion-exchange membrane(AEM)electrolyzers toward the cathodic nitrate reduction reaction(NO_(3)RR)and anodic benzylamine oxidation reaction(BOR)could generate high value-added N-containing compounds simultaneously.The key challenge is to develop bifunctional electrocatalysts with a wide potential window,which can achieve highly efficient conversion of anode and cathode reactants.Herein,Ni_(3)Se_(4)with Se vacancies was prepared and employed as the cathode and anode of AEM electrolyzers for NO_(3)RR and BOR.^(15)N isotope-labeling online differential electrochemical mass spectrometry(DEMS)proved that ammonium was reduced from nitrates and revealed the reaction pathway of NO_(3)RR.The density functional theory calculation clarified that Se vacancies regulate d-band centers,and then further modulate the adsorption energy of adsorbed hydrogen,NO_(3)^(-)and intermediates on the Ni_(3)Se_(4)-60s surface in NO_(3)RR,so as to optimize the hydrogenation of NO_(3)^(-)into ammonia.Moreover,during the BOR,the Se vacancy can promote the adsorption of OH^(-),which is easier to form the active species of Ni OOH.The technical and economic evaluation exhibited that the cost of paired electrolysis is 1.21 times lower and the profit is 1.42 times higher than that of the unpaired electrolysis,which shows the economic attraction of paired electrolysis.This work delivers the guidance for the design of efficient catalysts for paired electrolysis in AEM electrolyzer toward the sustainable synthesis of value-added chemicals.