Bi plasmon-enhanced mesoporous Bi2MoO6/Ti3+ self-doped TiO2 microsphere heterojunctions as efficient visible-light-driven photocatalysts

Highlights: • Bi plasmon-enhanced mesoporous Bi₂MoO₆/Ti³⁺-TiO₂ microsphere heterojunction is given. • It possesses the narrow band gap and enhances the response to visible light region. • It exhibits excellent visible-light-driven photocatalytic performance. • The synergistic effect is Ti³⁺ self-doping, SPR of Bi and heterojunction structure. Bi plasmon-enhanced mesoporous Bi₂MoO₆/Ti³⁺ self-doped TiO₂ microsphere heterojunctions (Bi-BMO/TiO_2-x) have been synthesized by a mild hydrothermal method combined with an in situ solid-state chemical reduction process, and subsequently annealed at 400 °C in N₂ atmosphere. The prepared Bi-BMO/TiO_2-x photocatalysts are characterized by X-ray diffraction, N₂ adsorption, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results reveal that Ti³⁺ self-doped TiO₂ is loaded on surface of mesoporous Bi₂MoO₆ microsphere efficiently and metallic Bi is produced for surface plasmon resonance (SPR). Under visible-light irradiation, the heterojunctions photocatalyst shows excellent photodegradation and photoelectrochemical properties of ∼95% for phenol removal rate and 20 μA/cm² for photocurrent density, respectively, which is several times higher than that of single component. Moreover, it also has high photocatalytic oxygen production with a rate of 134 μmol h^-1 g^-1. The enhanced photocatalytic activities are mainly attributed to the existence of Ti³⁺ self-doping and heterojunction structure, which narrow the band gap to extend photoresponse to visible light region. Another reason is the influence of SPR of metallic Bi. They all promote the spatial separation and transfer of photogenerated charge carriers.