Trapping and further localization of photo-generated carriers by defects in a photocatalyst are crucial obstacles for enhancing the efficiency of hydrogen generation from water photolysis. In this paper, we reported a re-excitation mechanism of localized electrons assisted by infrared light for improving photocatalytic activity. Increasing hydrogen production is demonstrated when introducing infrared light for SnO2 quantum dots at a grain size smaller than twice its Debye length and supported on g-C3N4. Comparatively, in absence of infrared light, rich oxygen vacancies in these SnO2 quantum dots reduced the photocatalytic activity. The re-excitation of localized electrons would provide a viable approach to utilize electrons more efficiently in the photocatalytic or other catalytic fields.
