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 TiO2 composite, in which Cu nanoclusters with a small size of 1-3 nm are decorated on brookite TiO2 quasi nanocube (BTN) surfaces (hereafter referred to as Cu-BTN), is synthesized via a one-pot hydrothermal process and then used as photocatalyst for CO2 reduction. It was found that the decoration of Cu nanoclusters on BTN surfaces can improve the activity and selectivity of CO2 photoreduction to CH4 , and 1.5 % Cu-BTN gives a maximum overall photocatalytic activity (150.9 μmol g-1  h-1 ) for CO/CH4 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 CH4 as compared to CO due to the number of surface oxygen vacancies and the CO2 /H2 O adsorption behavior, which differs from that of the pristine BTN. The present results demonstrate that brookite TiO2 would be a potential effective photocatalyst for CO2 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 CO2 reduction to CH4 .