The roles of surface oxygen vacancy over Mg4Ta2O9-x photocatalyst in enhancing visible-light photocatalytic hydrogen evolution performance

Abstract Extending the light absorption range of wide-band-gap semiconductor oxides is crucial to the effective solar-hydrogen energy conversion. Here, we introduced surface oxygen vacancies into Mg 4 Ta 2 O 9 and constructed a narrow band-gap Mg 4 Ta 2 O 9-x photocatalyst by a simple low temperature reduction method. The as-synthesized Mg 4 Ta 2 O 9-x exhibits a significantly extended absorption edge in visible light range, which originates from the intermediate defect level band and electronic states created by introducing surface oxygen vacancy. With the same Pt loaded content (0.5 wt%), the Pt-loaded Mg 4 Ta 2 O 9-x exhibits the excellent photocatalytic stability and higher hydrogen evolution activity (4.42 μmol·h − 1 ) than the Pt-loaded Mg 4 Ta 2 O 9 (0.14 μmol·h − 1 ) under visible light irradiation.