Ultrathin Ti-doped WO 3 nanosheets realizing selective photoreduction of CO 2 to CH 3 OH.

Arduous CO 2 activation and sluggish charge transfer retard the photoreduction of CO 2 to CH 3 OH with high efficiency and selectivity. Here, we fabricate ultrathin Ti-doped WO 3 nanosheets possessing approving active sites and optimized carrier dynamics as a promising catalyst. Quasi in situ X-ray photoelectron spectroscopy and synchrotron-radiation X-ray absorption near-edge spectroscopy firmly confirm that the true active sites for CO 2 reduction are the W sites rather the Ti sites, while the Ti dopants can facilitate charge transfer, which accelerates the generation of crucial COOH* intermediates as revealed by in situ Fourier-transform infrared spectroscopy and density functional theory calculations. Besides, the Gibbs free energy calculations also validate that Ti doping can lower the energy barrier of CO 2 activation and CH 3 OH desorption by 0.22 eV and 0.42 eV, respectively, thus promoting the formation of CH 3 OH. In consequence, the Ti-doped WO 3 ultrathin nanosheets show a superior CH 3 OH selectivity of 88.9% and reach a CH 3 OH evolution rate of 16.8 μmol g -1 h -1 , about 3.3 times higher than that on WO 3 nanosheets. This work sheds light on promoting CO 2 photoreduction to CH 3 OH by rational elemental doping.