One-step calcination synthesis of WC–Mo2C heterojunction nanoparticles as novel H2-production cocatalysts for enhanced photocatalytic activity of TiO2

Abstract

Hexagonal molybdenum carbide (Mo₂C) as a high-efficiency non-noble cocatalyst has been widely applied in the photocatalytic H₂-generation area due to its platinum-like H⁺-adsorption potential, high thermal stability, and excellent electrochemistry properties. However, Mo₂C possesses relatively low electrical conductivity and strong Mo–H bonds, resulting in a limited H₂-generation activity of Mo₂C-modified photocatalysts. In this paper, a tungsten carbide–molybdenum carbide (WC–Mo₂C) heterojunction was constructed by introducing WC with high electrical conductivity into Mo₂C for weakening the Mo–H bond. The carbon-coated WC–Mo₂C heterojunction nanoparticles (WC–Mo₂C@C) by one-step calcination of a controllable ratio mixture (melamine (MA), (NH₄)₆Mo₇O₂₄ and (NH₄)₆H₂W₁₂O₄₀) at 800 °C were decorated on a TiO₂ surface to form WC–Mo₂C@C/TiO₂ for the enhanced hydrogen-production performance of TiO₂. The H₂-production results showed that the highest H₂-production rate of WC–Mo₂C@C/TiO₂ reached 903 μmol h⁻¹ g⁻¹ (AQE = 2.70%), which was 90.3, 3.6 and 2.5 times higher than that of TiO₂, Mo₂C@C/TiO₂, and WC@C/TiO₂, respectively. The enhanced performance of WC–Mo₂C@C/TiO₂ can be attributed to the addition of W element being able to simultaneously increase the conductivity of Mo₂C and weaken the Mo–H bond for boosting the photocatalytic H₂-production reaction of TiO₂. This work provides a feasible strategy to explore efficient Mo₂C-modified photocatalysts in the H₂-generation field.