N2 plasma-assisted surface modification of g-C3N4 nanosheets for enhanced photocatalytic H2O2 production

Abstract

Artificial photosynthesis of H₂O₂ is an environmental-friendly, sustainable and cost-effective approach to achieve scalable solar fuel production, which only utilizes water and oxygen as the source materials and renewable solar energy as the energy source. Efficient synthesis and soft surface modification of nanomaterials are of great importance to realize high photocatalytic H₂O₂ production performance. Herein, a two-step calcination strategy is applied to obtain ultrathin g-C₃N₄ nanosheets. Afterward, a facile microwave plasma with N₂ as the carrier gas is employed to modify the surface structure and pore structure of the g-C₃N₄ nanosheets. High-energy electrons and highly active free radicals from N₂ plasma can not only induce carbon vacancies but also oxygen-containing functional groups, which effectively modulate the energy levels, facilitate the interaction of water with the catalyst, and promote the separation and transfer of photogenerated charge carriers. After transient N₂ plasma processing, the photocatalytic H₂O₂ generation of ultrathin g-C₃N₄ nanosheets shows remarkable improvement. This study indicates that plasma treatment is a rapid, mild, effective and promising strategy to modify nanomaterials for high photocatalytic performance.