Boosting the H2-evolution performance of TiO2/Au photocatalyst by the facile addition of thiourea molecules

Noble metallic Au as an electron cocatalyst has been extensively applied in improving the photocatalytic H2-production efficiency of photocatalysts owing to its excellent conductivity. However, a slow H2-production rate on the Au surface results in the limited H2-evolution efficiency of Au-modified photocatalysts. In this paper, thiourea molecules as a modulator can be self-assembled on the Au surface of TiO2/Au photocatalyst (TiO2/Au-S) due to the strong interaction between Au and S to promote the interfacial H2-production reaction of TiO2/Au photocatalyst. The TiO2/Au-S photocatalyst was synthesized through a two-step route containing the direct photodeposition of Au nanoparticles on the TiO2 surface and subsequent self-assembly of thiourea molecules by a simple impregnation method. According to the experimental results, the highest H2-evolution rate of resultant TiO2/Au-S reached 120.15 μmol h−1, which was 11.9, 1.6 and 9.1 times larger than that of TiO2, TiO2/Au, and TiO2/SC(NH2)2, respectively. A photocatalytic mechanism is put forward for the promoted H2-production rate of TiO2/Au-S, namely, the synergistic effect of Au nanoparticles and assembled thiourea molecules as electron cocatalysts. This work provides a new insight to develop noble-metal modified photocatalysts in the photocatalytic H2-evolution field.