Fig. 4: Photo-chemical properties.

a Conduction band minimum and b Valence band maximum charge distributions of Cu-def-WO3. The grey, red and blue balls represent W, O and Cu atoms, respectively. In situ EPR monitor of c ·OOH and d ·OH radicals trapped by DMPO over WO3, def-WO3 and Cu0.029-def-WO3 under light. e Time-dependent PL intensity of 7-hydroxycoumain from the reaction of coumarin and ·OH over WO3, def-WO3 and Cu0.029-def-WO3. f GC-MS of the produced HCHO with isotopic labelled H218O or 18O2 in the presence of 19 bar CH4 and 1 bar O2 and 3 mL H2O over Cu0.029-def-WO3.