Recyclable Quasi‐Homogeneous Carbon Nitride Colloidal Catalyst for Sustainable Photocatalytic H ₂ O ₂ Generation

Abstract Graphitic carbon nitride (g‐C 3 N 4 ) photocatalysts have attracted growing interest for the eco‐friendly, solar‐driven synthesis of hydrogen peroxide (H 2 O 2 ). However, the catalytic efficiency remains limited by poor accessibility of reactive sites due to the hydrophobic nature and aggregation tendency of conventional g‐C 3 N 4 . Here, we report a hydrophilic g‐C 3 N 4 colloidal photocatalyst, synthesized via potassium ion (K⁺) incorporation and surface grafting with sulfonylcyanide groups, which enables quasi‐homogeneous photocatalytic H 2 O 2 production (7,886 µmol g⁻¹ h⁻¹), surpassing most reported g‐C 3 N 4 ‐based heterogeneous systems. The sulfonylcyanide groups facilitate O 2 adsorption and reduction, while synergistically promoting charge separation in conjunction with K⁺ ions. This work demonstrates the potential of hydrophilic g‐C 3 N 4 colloids in quasi‐homogeneous catalysis and presents a versatile strategy for designing advanced g‐C 3 N 4 ‐based photocatalysts for sustainable chemical synthesis.