A facile hydrothermal synthesis of carbon dots modified g-C3N4 for enhanced photocatalytic H2-evolution performance

Carbon dots (CDs)/g-C3N4 is a promising photocatalyst to split water for H-2 production; however, the synthesis of CDs/g-C3N4 is usually rigorous and involves multiple steps, which limits its practical application. In this study, a facile hydrothermal approach was developed to prepare CDs/g-C3N4 photocatalysts using L-ascorbic acid and g-C3N4 as the precursors. Upon in situ thermal polymerization of L-ascorbic acid on the g-C3N4 surface, the carbon dots were homogeneously and solidly modified on the g-C3N4 surface. The CDs/g-C3N4 photocatalysts showed higher photocatalytic performance for H-2 production than g-C3N4 under UV light irradiation using lactic acid as the sacrificial agent. The improved photocatalytic performance of CDs/g-C3N4 was mainly attributed to rapid interfacial charge transfer. After a Pt co-catalyst was loaded, the Pt-CDs/g-C3N4 catalyst formed exhibited a further improved photocatalytic performance for H-2 production and could even split pure water to produce H-2. Considering our present economic and facile synthetic approach for the modification of carbon dots on the surface of g-C3N4 photocatalysts, the as-prepared CDs/g-C3N4 photocatalysts will be promising for practical use in water splitting.