Rational Design of High‐Concentration Ti<sup>3+</sup> in Porous Carbon‐Doped TiO<sub>2</sub> Nanosheets for Efficient Photocatalytic Ammonia Synthesis
Qing Han, Chongbei Wu, Haimiao Jiao, Ruoyu Xu, Yuze Wang, Jijia Xie, Qian Guo, Junwang Tang
Abstract
Abstract 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 2 reduction under ambient conditions. Herein, porous carbon‐doped anatase TiO x (C‐TiO x ) nanosheets with high‐concentration active sites of Ti 3+ are presented, which are produced by layered Ti 3 SiC 2 through a reproducible bottom‐up approach. It is shown that the high‐concentration Ti 3+ sites are the major species for the significant increase in N 2 photoreduction activity by the C‐TiO x . Such bottom‐up substitutional doping of C into TiO 2 is responsible for both visible absorption and generation of Ti 3+ concentration. Together with the porous nanosheets morphology and the loading of a Ru/RuO 2 nanosized cocatalyst for enhanced charge separation and transfer, the optimal C‐TiO x with a Ti 3+ /Ti 4+ ratio of 72.1% shows a high NH 3 production rate of 109.3 µ mol g −1 h −1 under visible‐light irradiation and a remarkable apparent quantum efficiency of 1.1% at 400 nm, which is the highest compared to all TiO 2 ‐based photocatalysts at present.