Selectively anchoring Cu(OH)2 and CuO on amine-modified brookite TiO2 for enhanced CO2 photoreduction

Photocatalytic CO2 reduction is a promising approach for reducing CO2 emissions and achieving the goal of carbon neutrality. In this work, selectively coupling Cu(OH)2 and CuO with amine-modified brookite TiO2 (NH2–B–TiO2) has been achieved by a simple precipitation method. The results show that CuO is better than Cu(OH)2 as a co-catalyst to enhance the CO2 photoreduction capability of NH2–B–TiO2. The highest rates of CO2 conversion to CH4 and CO of NH2–B–TiO2–CuO composite reach 6.05 and 3.25 μmol h−1 g−1, respectively, which is higher than 8 times the yield of CH4 of NH2–B–TiO2. It is proposed that the NH2–B–TiO2–CuO composite offers an effective charge transfer through the formation of a p–n junction between NH2–B–TiO2 and CuO interfaces, while in the NH2–B–TiO2–Cu(OH)2 composite, the Cu(OH)2 dominantly serves as an electron sink to capture photo-induced electrons, promoting photo-induced carrier separation. This work provides an ingenious synthetic method for selectively anchoring Cu(OH)2 and CuO on semiconductors with different charge transfer routes for an efficient CO2 photoreduction. Graphical abstract