Interface modification by defect engineering for g-C₃N₄/LaPO_4−x nanorods towards efficient CO₂ photoreduction

In this work, a series of specific surface defects are introduced at the interface of LaPO₄/g-C₃N₄ composites. The photoreduction of CO₂ into CO was performed to evaluate the catalytic performance. Among all photocatalysts, g-C₃N₄ composited with La200 (g-C₃N₄/La200) samples exhibits the best photocatalytic activity. The yield rate of CO for g-C₃N₄/La200 is almost 2 times, 2 times, 5 times and 18 times higher than that of La200, g-C₃N₄, pristine LaPO₄ and g-C₃N₄/LaPO₄ samples, respectively. It was revealed that these specific defects (oxygen vacancies) were successfully introduced onto LaPO_4−x nanorods’ surface (La200 samples) and the g-C₃N₄ shell completely covered the LaPO_4−x nanorods (La200). The introduced oxygen vacancies induced a new defect level below the CB (conduction band bottom) of LaPO₄. The photoexcited electrons in the LUMO energy levels of g-C₃N₄ can easily transfer to the defect energy levels of LaPO_4−x. Consequently, the response in the visible region is extended and the photoinduced holes and electrons are separated efficiently. As a result, the La200 samples represented enhanced activity towards CO₂ reduction into carbon monoxide. This study may offer better guidance for designing and fabricating novel heterostructure photocatalysts by defect engineering with excellent photocatalytic activity and stability.