In situ constructed oxygen-vacancy-rich MoO3−x/porous g-C3N4 heterojunction for synergistically enhanced photocatalytic H2 evolution

Abstract

A simple method was developed for enhanced synergistic photocatalytic hydrogen evolution by in situ constructing of oxygen-vacancy-rich MoO_3−x/porous g-C₃N₄ heterojunctions. Introduction of a MoO_3−x precursor (Mo(OH)₆) solution into g-C₃N₄ nanosheets helped to form a porous structure, and nano-sized oxygen-vacancy-rich MoO_3−x in situ grew and formed a heterojunction with g-C₃N₄, favorable for charge separation and photocatalytic hydrogen evolution (HER). Optimizing the content of the MoO_3−x precursor in the composite leads to a maximum photocatalytic H₂ evolution rate of 4694.3 μmol g⁻¹ h⁻¹, which is approximately 4 times higher of that of pure g-C₃N₄ (1220.1 μmol g⁻¹ h⁻¹). The presence of oxygen vacancies (OVs) could give rise to electron-rich metal sites. High porosity induced more active sites on the pores' edges. Both synergistically enhanced the photocatalytic HER performance. Our study not only presented a facile method to form nano-sized heterojunctions, but also to introduce more active sites by high porosity and efficient charge separation from OVs.