Construction of TiO2–MnO2 0D–2D nanostructured heterojunction for enhanced photocatalytic hydrogen production

Abstract

The low transfer efficiency and high recombination loss of photo-induced carriers in TiO₂ are significant issues that hinder its photocatalytic activity. Herein, TiO₂ nanoparticles (∼5 nm) were loaded on MnO₂ nanosheets (40–60 nm) to form TiO₂–MnO₂ nanostructured heterojunction (0D–2D nanostructure unit), possessing a high specific surface area. The separation/transfer efficiency of photocarriers and the solar absorptivity of TiO₂–MnO₂ were improved, thus enhancing solar energy conversion efficiency. The enhanced transfer efficiency of carriers is associated with the 2D network of MnO₂ and abundant oxygen vacancies serving as media for electron transport. The enhanced visible absorption and reduced recombination should be attributed to the narrowed bandgap and modified energy band structure. The photocurrent of TiO₂–MnO₂ increased obviously and the H₂ production rate increased to 0.38 mmol g⁻¹ h⁻¹, compared with that of pure TiO₂ (0.25 mmol g⁻¹ h⁻¹). The enhanced photocatalytic properties are also associated with the excellent water oxidation kinetics caused by MnO₂ nanosheets.