π-Stacked organic heterojunction enabled efficient hydrogen peroxide photoproduction

Hydrogen peroxide (H₂O₂) finds wide application in disinfection, chemical production, and bleaching owing to its sustainability and ease of storage compared to hydrogen. However, the current industrial engineering practices for producing photocatalysts used in H₂O₂ generation face challenges such as low yields with organic catalysts and high costs associated with inorganic catalysts. In light of these challenges, we investigate a viable method utilizing a simple condensation reflux technique to synthesize pure organic heterojunction photocatalysts featuring a π-π stacked structure derived from graphitized carbon nitride (melem) and meso-tetrakis (4-carboxyphenyl) porphyrin, enabling efficient H₂O₂ production without the necessity of sacrificial agents. The synthesized catalyst demonstrates an impressive H₂O₂ production rate of 106 mmol/h.g.L under seawater conditions and 77.67 mmol/h.g.L under pure water conditions in ambient air. Coupling to a solar evaporator, an H₂O₂ concentration reaches 0.88 wt%. Transient absorption spectroscopy revealed ultrafast charge separation which enabled efficient photocatalysis.