Boosting the oxygen evolution reaction via the reconstruction of an M(OH)x/Fe3O4 catalyst†

For large-scale hydrogen production from electrocatalysis of water, Ni- and/or Fe-based catalysts were commonly used but were limited by the ultrahigh overpotential and poor stability at a high current density (>500 mA cm⁻²). Here, the reconstruction of M(OH)_x/Fe₃O₄ (M = Ni, Fe) arrays has been performed for boosting the oxygen evolution reaction (OER). The prepared M(OH)_x/Fe₃O₄ grown on iron foam (M(OH)_x/Fe₃O₄/IF) catalysts exhibited low overpotentials of 214 and 311 mV for the OER at current densities of 50 and 500 mA cm⁻², respectively. In addition, an excellent stability up to 70 h of operation was achieved at a current density of 10 mA cm⁻² in 1 M KOH. The in situ Raman spectra revealed that the reconstruction of M(OH)_x/Fe₃O₄/IF boosted the OER activity. Theoretical calculations revealed favorable absorption of O₂ at the Ni site of M(OH)_x/Fe₃O₄/IF during the OER. This work highlights the reconstruction of structurally definite catalysts for promoting the catalytic activity toward the OER and the large-scale electrocatalysis of water.