Tailoring the surface and interface structures of carbon nitride for enhanced photocatalytic self-Fenton process in pollutant degradation

Fenton technology faces significant challenges due to external H₂O₂ dependency and inadequate Fe²⁺ regeneration. Constructing a photocatalytic self-Fenton system is a promising strategy, but it is hindered by slow charge dynamics and low mass transfer of reactant ions. Here, we present a multi-engineering co-modified carbon nitride (OCN) for efficient photocatalytic self-Fenton reactions. By calcining a mixture of OCN and sodium cyanoborohydride (NaBH₃CN), abundant surface defects (CN groups and N vacancies) and doping (B and O) were simultaneously introduced. NaBH₃CN breaks OCN nanosheets into smaller fragments, which then stack into larger pieces, creating multiple order-disorder interfaces. These modifications synergistically tune the band structure, enhance charge dynamics, and facilitate spatially separated redox centers. More importantly, the abundant N vacancies effectively adsorb and activate O₂. The electron-rich regions around B and CN sites, derived from their electron-withdrawing effect, enhance H⁺ and Fe³⁺ adsorption on the catalyst surface, thereby accelerating H₂O₂ generation and Fe³⁺ photoreduction. The H₂O₂ and Fe²⁺ generated in the same region rapidly interact, initiating the Fenton reaction to degrade pollutants and enhancing activation kinetics by shortening contact distance. This work provides new insights into the design of efficient and eco-friendly photocatalysis-self-Fenton systems for wastewater treatment by tailoring the surface and interface structures of catalysts.