Enriching surface-ordered defects on WO(3) for photocatalytic CO(2)-to-CH(4) conversion by water.

Defect engineering has been widely applied in semiconductors to improve photocatalytic properties by altering the surface structures. This study is about the transformation of inactive WO(3) nanosheets to a highly effective CO(2)-to-CH(4) conversion photocatalyst by introducing surface-ordered defects in abundance. The nonstoichiometric WO(3-x) samples were examined by using aberration-corrected electron microscopy. Results unveil abundant surface-ordered terminations derived from the periodic {013} stacking faults with a defect density of 20.2%. The {002} surface-ordered line defects are the active sites for fixation CO(2), transforming the inactive WO(3) nanosheets into a highly active catalyst (CH(4): O(2) = 8.2: 16.7 μmol h(-1)). We believe that the formation of the W-O-C-W-O species is a critical step in the catalytic pathways. This work provides an atomic-level comprehension of the structural defects of catalysts for activating small molecules.