p–n tungsten oxide homojunctions for Vis-NIR light-enhanced electrocatalytic hydrogen evolution

Abstract

Based on energy band engineering theory, a p–n homojunction of metal oxides was designed to overcome the recombination of photogenerated carriers and inappropriate hydrogen adsorption energy. A novel p–n tungsten oxide homojunction was successfully synthesized by tuning oxygen vacancies and phosphorus-doping. Based on the synergies of Mxenes, a Vis-NIR light-enhanced electrocatalytic hydrogen evolution system was accomplished with a small overpotential of 44 mV (at 10 mA cm⁻²) and a low Tafel slope of 41 mV dec⁻¹, which performed much more efficiently than in darkness and comparably to noble-metal catalysts (Pt and Pt/C). Moreover, the as-synthesized samples offered a distinct advantage of long-term stability for more than 24 h both with and without light irradiation. The design philosophy of p–n homojunctions opens a prospect of utilizing light-activated metal oxides to integrate catalysis with solar energy and electrical energy.