The regulation of interface structure improves the performance of the MoxOy/Co3O4 electrocatalytic oxygen evolution reaction in acidic media

This paper proposes a multi-level structure design strategy, a dense cobalt oxide layer ( d -Co 3 O 4 ), a cobalt oxide catalytic layer ( h -Co 3 O 4 ), and an amorphous molybdenum oxide ( a -Mo x O y ) co-catalytic layer are constructed layer by layer on nickel foam (NF) through the combination of electro-deposition and oxidation. The a -Mo x O y / h -Co 3 O 4 / d -Co 3 O 4 /NF composite catalyst with both high catalytic activity and high stability was thus prepared. The main function of the d -Co 3 O 4 layer is to prevent NF from coming into direct contact with acidic media to stop its electrochemical corrosion. The h -Co 3 O 4 catalytic layer thus acquires a larger specific surface area, thereby exposing more active sites. The main function of the a -Mo x O y co-catalytic layer is to regulate the electronic structure on the surface of h -Co 3 O 4 , reduce the electron cloud density of the Co active sites, and thereby promote the adsorption and oxidation of the oxygen in a water molecule on it. The electrochemical test results show that the overpotential of a -Mo x O y / h -Co 3 O 4 / d -Co 3 O 4 /NF at a current density of 10 mA cm –2 is 254 mV, the Tafel slope is 118 mV dec –1 , and the stability exceeds 12 h in 0.5 mol L –1 H 2 SO 4 . Raman, X-ray photoelectron spectroscopy characterization and theoretical calculations indicate that the a -Mo x O y -Co 3 O 4 interface promotes the transfer of electrons from Co to Mo, optimizes the electronic structure of the active site, and reduces the adsorption and desorption energy barriers of the reaction intermediates OOH*, OH* and O* thereby enhancing the oxygen evolution reaction performance of the catalyst. This study provides a new structural design strategy for constructing stable transition metal-based oxide catalysts on NF for acidic oxygen evolution reaction.