LED-driven controlled deposition of Ni onto TiO for visible-light expanded conversion of carbon dioxide into C-C alkanes.

Photocatalytic gas-phase hydrogenation of CO into alkanes was achieved over TiO-supported Ni nanoparticles under LED irradiation at 365 nm, 460 nm and white light. The photocatalysts were prepared using photo-assisted deposition of Ni salts under LED irradiation at 365 nm onto TiO P25 nanoparticles in methanol as a hole scavenger. This procedure yielded 2 nm Ni particles decorating the surface of TiO with a nickel mass content of about 2%. Before the photocatalytic runs, Ni/TiO was submitted to thermal reduction at 400 °C in a 10% H atmosphere which induced O-defective TiO substrates. The formation of oxygen vacancies, Ti centers and metallic Ni sites upon photocatalytic CO hydrogenation was confirmed by EPR analysis. XPS under reaction conditions suggested a strong metal-support interaction and the co-existence of zero and divalent Ni states. These photoactive species enhanced the photo-assisted reduction of CO below 300 °C to yield CO, CH and CH as final products.