Exchange of CO with CO as Reactant Switches Selectivity in Photoreduction on Co-ZrO from C Paraffin to Small Olefins.

Photocatalytic reduction of CO into C hydrocarbons completes a C-neutral cycle. The reaction pathways of photocatalytic generation of C paraffin and CH from CO are mostly unclear. Herein, a Co-ZrO photocatalyst converted CO into C paraffin, while selectively converting CO into CH and CH (6.0±0.6 μmol h g , 70 mol %) only under UV/Visible light. The photocatalytic cycle was conducted under CO and H, with subsequent evacuation and flushing with CO. This iterative process led to an increase in the population of CH and CH up to 61-87 mol %, attributed to the accumulation of CH species at the interface between Co nanoparticles and the ZrO surface. CO adsorbed onto the O vacancies of the ZrO surface, with resulting COH species undergoing hydrogenation on the Co surface to yield C paraffin using either H or HO (g, l) as the reductant. In contrast, CO adsorbed on the Co surface, converted to HCOH species, and then split into CH and OH species at the Co and O vacancy sites on ZrO, respectively. This comprehensive study elucidates intricate photocatalytic pathways governing the transformation of CO into paraffin and CO to olefins.