Integral morphology and structure design of poly (heptazine imide) for efficient utilization of visible light generated charge carriers in proton reduction reactions

Abstract

Sufficient utilization of visible-light generated charge carriers in proton reduction reactions is of great significance for the development of effective solar-fuel technologies. Achieving simultaneous bulk rapid transfer and surface efficient extraction of charge carriers is still very challenging. Herein, it is found for the first time ammonium persulfate (APS) can significantly influence polymerization processes of C₃N₄ (CN) from melamine to poly (heptazine imide) (PHI) under the simultaneous oxygen doping and etching effect of SO₄²⁻. PHI with high crystallinity, porous structure, and in-situ oxygen doping was therefore obtained through one-step APS-assisted salt strategy. Benefiting from sufficient visible-light absorption and upshifted conduction band originating from regulated electronic structure and optimized morphology through APS modification, the as-prepared PHI achieved a H₂ evolution activity of 3274.23 μmol h⁻¹ g⁻¹ (λ  > 420 nm), which is appropriately 148 and 19 times that of conventional and crystalline CN. This work opens up new opportunities for efficient photocatalysis.