Novel up-conversion N, S co-doped carbon dots/g-C3N4 photocatalyst for enhanced photocatalytic hydrogen evolution under visible and near-infrared light

Abstract

In photocatalytic splitting water for hydrogen evolution, narrow light response range and fast electron-hole recombination of g-C3N4 (CN) limit its photocatalytic activity. In this article, the N, S co-doped carbon dots (NSCDs) with up-converted property were loaded on CN nanosheets by thermal polymerization to obtain NSCDs/CN composite catalyst. Characterization, electrochemical researches and hydrogen evolution tests suggest that the photocatalytic activity of CN is greatly promoted by the introduction of NSCDs. Under visible and near-infrared irradiation, the hydrogen evolution rate is 5033.1 μmol g−1 h−1 of NSCDs-5/CN, which is 8.3 times higher than that of CN. The performance improvement is mainly attributed to the increased specific surface area, elevated hydrophilic surface, increased light absorption and suppressed carrier recombination of CN after the introduction of NSCDs. This work unveils the mechanism of the hydrogen evolution activity improvement in NSCDs-5/CN, and also offers a new prospect in the design of high-performance CN-based photocatalysts.