Highly efficient hydrogen evolution reaction, plasmon-enhanced by AuNP-l-TiO2NP photocatalysts
A set of AuNPs-L-TiO2NP nanoaggregates which showed efficient covering of the semiconductor's surface by AuNPs, as well as appropriate AuNP sizes for effective sensibilization were used as photocatalysts for the hydrogen evolution reaction (HER). Three aliphatic short-chain linkers: 3-mercaptopropionic acid (MPA), thioglycolic acid (TGA) and thiolactic acid (TLA) were used as stabilizing agents. The slight structure variations of the linkers did not produce differences in the AuNP size and morphology. However, it was interesting to show how the photocatalytic performance of the nanoaggregates is dependent on the linker present, as well as to determine the influence of the Au/TiO2 ratio. It was found that TGA gave the best performance at a longer irradiation time, though high amounts of H2 were also obtained for the other two linkers. Furthermore, for all samples large amounts of hydrogen were obtained, which are significantly higher than that usually obtained with plasmon-sensitized TiO2 nanostructures. In addition, high amounts of H2 were obtained after five catalytic cycles for all samples, showing the suitability of these nanoaggregates for the photoinduced HER.