One‐Pot Synthesis of Cu‐Nanocluster‐Decorated Brookite TiO 2 Quasi ‐Nanocubes for Enhanced Activity and Selectivity of CO 2 Photoreduction to CH 4

A new kind of metallic Cu‐loaded brookite TiO 2 composite, in which Cu nanoclusters with a small size of 1–3 nm are decorated on brookite TiO 2 quasi nanocube (BTN) surfaces (hereafter referred to as Cu‐BTN), is synthesized via a one‐pot hydrothermal process and then used as photocatalyst for CO 2 reduction. It was found that the decoration of Cu nanoclusters on BTN surfaces can improve the activity and selectivity of CO 2 photoreduction to CH 4 , and 1.5 % Cu‐BTN gives a maximum overall photocatalytic activity (150.9 μmol g −1  h −1 ) for CO/CH 4 production, which is ≈11.4 and ≈3.3 times higher than those of pristine BTN (13.2 μmol g −1  h −1 ) and Ag‐BTN (45.2 μmol g −1  h −1 ). Moreover, the resultant Cu‐BTN products can promote the selective generation of CH 4 as compared to CO due to the number of surface oxygen vacancies and the CO 2 /H 2 O adsorption behavior, which differs from that of the pristine BTN. The present results demonstrate that brookite TiO 2 would be a potential effective photocatalyst for CO 2 photoreduction, and that Cu nanoclusters can act as an inexpensive and efficient co‐catalyst alternative to the commonly used noble metals to improve the photoactivity and selectivity for CO 2 reduction to CH 4 .