A combined experimental and theoretical study of RuO 2 /TiO 2 heterostructures as a photoelectrocatalyst for hydrogen evolution.

We report a joint experimental and theoretical study of RuO 2 /TiO 2 heterostructures. In the experimental section, mesoporous RuO 2 /TiO 2 heterostructures were prepared by impregnation of mesoporous TiO 2 nanoparticles which were synthesized from a new precursor, Na 2 [Ti(C 2 O 4 ) 3 ], in an aqueous solution of ruthenium(III) chloride followed by calcination at 300 °C. Using various techniques, the prepared TiO 2 and RuO 2 /TiO 2 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 2 is dispersed uniformly on the TiO 2 surface. The loading of RuO 2 on TiO 2 decreases the band gap energy and extends the absorption edge to the visible light region. This wide absorption extends the photoelectrocatalytic activity of RuO 2 /TiO 2 heterostructures. To obtain a deeper understanding of the increase of the photoelectrocatalytic activity of RuO 2 /TiO 2 heterostructures compared to pure TiO 2 , theoretical calculations at the density functional theory (DFT) level were performed on some model clusters of pure TiO 2 and the RuO 2 /TiO 2 heterostructure. The theoretical results elucidated that the recombination ratio of electron-hole pairs decreases effectively for RuO 2 /TiO 2 compared to pure TiO 2 .