Rational Design of High-Concentration Ti 3+ in Porous Carbon-Doped TiO 2 Nanosheets for Efficient Photocatalytic Ammonia Synthesis

Photocatalytic ammonia synthesis is exciting but quite challenging with a very moderate yield at present. One of the greatest challenges is to develop highly active centers in a photocatalyst for N reduction under ambient conditions. Herein, porous carbon-doped anatase TiO (C-TiO ) nanosheets with high-concentration active sites of Ti are presented, which are produced by layered Ti SiC through a reproducible bottom-up approach. It is shown that the high-concentration Ti sites are the major species for the significant increase in N photoreduction activity by the C-TiO . Such bottom-up substitutional doping of C into TiO is responsible for both visible absorption and generation of Ti concentration. Together with the porous nanosheets morphology and the loading of a Ru/RuO nanosized cocatalyst for enhanced charge separation and transfer, the optimal C-TiO with a Ti /Ti ratio of 72.1% shows a high NH production rate of 109.3 µmol g h under visible-light irradiation and a remarkable apparent quantum efficiency of 1.1% at 400 nm, which is the highest compared to all TiO -based photocatalysts at present.