A combined experimental and theoretical study of RuO/TiO heterostructures as a photoelectrocatalyst for hydrogen evolution.

We report a joint experimental and theoretical study of RuO/TiO heterostructures. In the experimental section, mesoporous RuO/TiO heterostructures were prepared by impregnation of mesoporous TiO nanoparticles which were synthesized from a new precursor, Na[Ti(CO)], in an aqueous solution of ruthenium(III) chloride followed by calcination at 300 °C. Using various techniques, the prepared TiO and RuO/TiO heterostructures were extensively characterized. The photoelectocatalytic application of the as-prepared heterostructures was then investigated toward the hydrogen evolution reaction (HER). The results illustrated that RuO is dispersed uniformly on the TiO surface. The loading of RuO on TiO decreases the band gap energy and extends the absorption edge to the visible light region. This wide absorption extends the photoelectrocatalytic activity of RuO/TiO heterostructures. To obtain a deeper understanding of the increase of the photoelectrocatalytic activity of RuO/TiO heterostructures compared to pure TiO, theoretical calculations at the density functional theory (DFT) level were performed on some model clusters of pure TiO and the RuO/TiO heterostructure. The theoretical results elucidated that the recombination ratio of electron-hole pairs decreases effectively for RuO/TiO compared to pure TiO.