Artificial photosynthesis of H2O2 over a self-assembled two-dimensional g-C3N4 film

Abstract

Photocatalytic H₂O₂ generation is an efficient approach for the conversion of solar energy into chemical energy and is a potentially more sustainable alternative to the traditional anthraquinone process. Herein, porous g-C₃N₄ nanosheets (O-CN) were successfully prepared via a thermal polycondensation-assisted oxidation etching method. Subsequently, an O-CN thin-film photocatalyst was controllably fabricated using a simple interfacial self-assembly technique, leading to a per-unit-mass O-CN enhanced photocatalytic H₂O₂ yield. The optimal film structure of O-CN with a yield of 2.4 × 10⁴ μM g⁻¹ h⁻¹ showed excellent photocatalytic activity for H₂O₂ production under visible-light irradiation for 3 h, delivering a 3.5-fold and 5.6-fold yield enhancement compared with the bare O-CN powder and bulk g-C₃N₄, respectively. Compared with the g-C₃N₄-based powder photocatalyst, the O-CN film demonstrated an improved electron-transport capability along the in-plane direction and increased lifetime of photoexcited charge carriers because of the quantum confinement effect. Experimental results reveal that the photocatalytic selective oxygen reduction reaction (ORR) can be considered a promising strategy for H₂O₂ production using the O-CN film system. This work provides a design guide to develop efficient photocatalytic film-reactors for H₂O₂ generation.