Rationally Designed S-Scheme CeO 2 /g-C 3 N 4 Heterojunction for Promoting Visible Light Driven CO 2 Photoreduction into Syngas.

Exploring low-cost visible light photocatalysts for CO 2 reduction to produce proportionally adjustable syngas is of great significance for meeting the needs of green chemical industry. A S-Scheme CeO 2 /g-C 3 N 4 (CeO 2 /CN) heterojunction was constructed by using a simple two-step calcination method. During the photocatalytic CO 2 reduction process, the CeO 2 /CN heterojunction can present a superior photocatalytic performance, and the obtained CO/H 2 ratios in syngas can be regulated from 1 : 0.16 to 1 : 3.02. In addition, the CO and H 2 production rate of the optimal CeO 2 /CN composite can reach 1169.56 and 429.12 μmol g -1  h -1 , respectively. This superior photocatalytic performance is attributed to the unique S-Scheme photogenerated charge transfer mechanism between CeO 2 and CN, which facilitates rapid charge separation and migration, while retaining the excellent redox capacity of both semiconductors. Particularly, the variable valence Ce 3+ /Ce 4+ can act as electron mediator between CeO 2 and CN, which can promote electron transfer and improve the catalytic performance. This work is expected to provide a new useful reference for the rational construction of high efficiency S-Scheme heterojunction photocatalyst, and improve the efficiency of photocatalytic reduction of CO 2 , promoting the photocatalytic reduction of CO 2 into useful fuels.