Synthesis Of NiFe-based Catalysts By Successive Ionic Layer Adsorption And Reaction For The Oxygen Evolution Reaction

Water electrolysis（2H₂O→2H₂+O₂）is one of the most promising approaches to energy storage and conversion as it is a cdean and renewable technology.Kinetically,the anodic oxygen evolution reaction（OER）is sluggish compared with the cathodic hydrogen evolution reaction（HER）.Enormous effort has been devoted to finding high-performance nonprecious electrocatalysts for OER that are comparable to or better than the benchmark precious Ru and Ir oxides.These include hydroxides,sulfides,selenides and phosphides of the transition metals.In particular,various NiFe-based nano-compounds have been extensively investigated as effective electrocatalysts for OER in alkaline media.These compounds are actually semiconductors,and have a lower conductivity than metals.Thick films of these semiconductors would increase their OER overpotential due to the increase in charge transfer resistance.For this reason IR compensation is usually employed to minimize the impact of conductivity on OER catalytic performances.However,controlling the dosage of these materials on highly conducting substrates with a large surface area would be a more practical way of enhancing their real OER performance.In this paper,three kinds of NiFe-based semiconductor electrocatalysts were controllable prepared by successive ionic layer adsorption and reaction（SILAR）and the high catalytic oxygen evolution performance has been obtained.1.A facile method was proposed for controllably syntheses of high-performance Fe（OH）₃/NiS electrocatalysts supported on coral-like CuO/Cu microarrays（15Fe（OH）₃/15NiS/c-CuO/Cu）.A smooth Cu surface was firstly converted to coral-like Cu microarrays by square wave potential pulses in 1 mol L^-1 H₂SO₄,and then to c-CuO/Cu microarrays by cyclic voltammetry in 1 mol L^-1 KOH.Finally,appropriate amounts of Fe（OH）₃ and NiS were loaded on the c-CuO/Cu microarrays in an easily controlled way by SILAR.This catalyst exhibits a very low OER overpotential of 257 mV at 10 mA cm^-2（with no IR compensation）in 1 M KOH and has long-term OER stability for at least 10 h.2.A facile method was proposed for controllably syntheses of high-performance F e（OH）₃/Ni（OH）₂ electrocatalysts supported on coral-like CuO/Cu microarrays（5Fe（OH）₃/15Ni（OH）₂/c-CuO/Cu）.Appropriate amounts of Fe（OH）₃ and Ni（OH）₂ were loaded on the CuO/Cu microarrays in an easily controlled way by SILAR.This catalyst exhibits a very low OER overpotential of 270 mV at 10 mA cm^-2（with no IR compensation）in 1 mol L^-1 KOH and has long-term OER stability for at least 10 h.3.A facile method was proposed for controllably syntheses of high-performance NiCoSx-Fe（OH）₃ electrocatalysts supported on coral-like CuO/Cu microarrays（NiCoSx-Fe（OH）₃/c-CuO/Cu）.We extend this method（SILAR）to the preparation of ternary element metal catalysts（NiCoSx-Fe（OH）₃/c-CuO/Cu）,and study the activity towards OERs in alkaline solution for the NiCoSx-Fe（OH）₃/c-CuO/Cu electrodes.