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

Photocatalytic CO 2 reduction is a promising approach for reducing CO 2 emissions and achieving the goal of carbon neutrality. In this work, selectively coupling Cu(OH) 2 and CuO with amine-modified brookite TiO 2 (NH 2 –B–TiO 2 ) 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 CO 2 photoreduction capability of NH 2 –B–TiO 2 . The highest rates of CO 2 conversion to CH 4 and CO of NH 2 –B–TiO 2 –CuO composite reach 6.05 and 3.25 μmol h −1  g −1 , respectively, which is higher than 8 times the yield of CH 4 of NH 2 –B–TiO 2 . It is proposed that the NH 2 –B–TiO 2 –CuO composite offers an effective charge transfer through the formation of a p–n junction between NH 2 –B–TiO 2 and CuO interfaces, while in the NH 2 –B–TiO 2 –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 CO 2 photoreduction. Graphical abstract