Photo-reduction assisted synthesis of W-doped TiO2 coupled with Au nanoparticles for highly efficient photocatalytic hydrogen evolution

Abstract

The practical applications of TiO₂ have been greatly suppressed by its low quantum yield, which arises from the rapid recombination of photo-induced electrons and holes, and poor solar efficiency, which is determined by its band gap. Herein, W-doped TiO₂ coupled with Au nanoparticles (W-TiO₂/Au) was designed and synthesized by a facile multi-step process. The W-doping in the TiO₂ lattice, on the one hand, can hinder the phase transition of TiO₂ from anatase to rutile structure, and the pure anatase structure is well preserved. On the other hand, W-doping can narrow the band gap of TiO₂ and result in oxygen vacancies, which may act as trapping sites to retard charge recombination. Furthermore, Au loading on the surface of TiO₂ can effectively suppress the recombination of photo-induced electrons and holes, leading to improvement in the quantum yields of TiO₂. Benefiting from the unique dual-hybrid strategy, the W-TiO₂/Au catalyst possesses a strong solar adsorption narrowed band gap, abundant active sites, strong synergetic coupling, enhanced electron transfer, and high efficiencies in H₂ generation. Its maximum H₂ generation rate can reach as high as 24 mmol g⁻¹ h⁻¹ under simulated solar light. A synergetic effect was proposed to explain the enhancement of the photocatalytic activity of TiO₂.