Surface doping is more beneficial than bulk doping to the photocatalytic activity of vanadium-doped TiO2

▶ Uneven doping of V ions in the surface lattice improves the photocatalytic activities of micrometer-sized TiO2. ▶ Bulk doping has detrimental effects on the photocatalytic activities except for a slight improvement happening at trace doping amounts. ▶ Deep trapping of charge carries at inner defects results in severe annihilation which reduces substantial quantities of effective charges for surface photocatalytic reactions. ▶ Surface defects retard recombination and facilitate interfacial charge transfer to enhance photocatalytic activity.