Kangqiang Li, Peng Diao
Oxygen vacancies in semiconductor photoanodes play a crucial role in facilitating charge transport and enhancing photoelectrochemical (PEC) performance. Herein, we report a facile and effective photocatalytic (PC) strategy to engineer oxygen vacancies in WO3 nanoflakes (NFs) via UV-vis irradiation in reducing media. As a result, the PEC water oxidation activity of WO3 NFs is markedly enhanced, delivering a nearly fourfold increase in limiting photocurrent density compared with pristine WO3. This pronounced improvement originates from photocatalytically induced oxygen vacancies generated through the partial reduction of W6+ to W5+ under reducing conditions. The introduction of oxygen vacancies leads to a sevenfold increase in carrier concentration, accompanied by an approximately 30% enhancement in bulk carrier separation efficiency and a substantial improvement in charge transfer efficiency at the WO3/electrolyte interface. Notably, this enhancement effect is universal across a wide range of reducing media, providing greater flexibility compared with conventional oxygen vacancy engineering strategies. These findings demonstrate the effectiveness and generality of PC oxygen vacancy engineering and highlight its potential applicability to other semiconductor photoanode systems.