Solar driven photocatalytic hydrogen evolution using graphitic-carbon nitride/NSGQDs heterostructures

The evolution of hydrogen by splitting water and sunlight renders a promising approach to produce scalable and sustainable carbon-free green energy. In this aspect, development of semiconductor heterostructure photocatalyst can spatially separate photogenerated electron-hole at the heterojunction interface and inhibit charge recombination to synergistically enhance photocatalytic performance. Herein, for the first time, we have designed exfoliated graphitic-carbon nitride (g-CN)/N, S co-doped graphene quantum dots (NSGQDs) heterostructure grown by one pot pyrolysis process. NSGQDs create strong π-π interactions with g-CN to construct an effective heterostructure and thus act as a efficient photosensitiser. We have made extensive investigations to understand the nature of g-CN/NSGQDs heterostructure, like optical and electrochemical properties and its shows improved charge transfer kinetics with reduced recombination. As a result, g-CN/NSGQDs heterostructure has achieved significantly high hydrogen evolution rate (HER) of 5.24 mmol h⁻¹ g⁻¹ under sunlight and with the apparent quantum yield (AQY) of 23.2%.