Engineering gradient porous substrates of Fe2O3/NiO for enhanced electrocatalytic hydrogen production

Water electrolysis is regarded as a promising and environmentally friendly approach to produce hydrogen through renewable energy sources. Electrocatalytic H2 production could be significantly improved by removing bubbles attached to the electrode surface. Herein, this work focused on designing porous gradient electrode (designated as SML-LMS-ALL) and characterized by a progressive increase in pore size from the outer edges to the inner area. Fe2O3/NiO electrode materials are rapidly prepared on the electrode by the combustion method. The experimental results show that this designed electrode can significantly improve the electrocatalytic H2 production activity. Compared to a homogeneous porous electrode, SML-LMS-ALL electrode has 6.2 times higher current density, excellent hydrogen bubble splitting activity, lower reactant transfer resistance and lower ohmic drop. The SML-LMS-ALL electrode demonstrates outstanding durability during water splitting, under the conditions of 20 mA cm-2 and 130 mV overpotential in 1.0 M KOH maintain over 200 h. This work shows that gradient porous electrode as substrate can significantly improve electrocatalytic H2 production activity.