Photo-reduction assisted synthesis of W-doped TiO2coupled 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.