Self-supply activation Fenton-like system for water purification using polyethyleneimine-driven electron pumps in polymeric carbon nitride

A hierarchically structured photocatalyst composite bead (CS-PG_0.5%-Fe) was developed in this study through a synergistic electronic modulation strategy, incorporating porphyrin-tailored polymeric carbon nitride (C₃N₄por), Fe(III) coordination, and polyethylenimine(PEI)-alginate cross-linked matrix to overcome challenges in Fenton-like wastewater treatment. The multi-component architecture was constructed via triple cross-linking treatment, with comprehensive mechanistic analysis employing in-situ characterization, reactive species tracking, and theoretical calculations to reveal the photo-driven H₂O₂ self-supply and activation processes. PEI acted as an electron pump and proton-relay mediator to enhance C₃N₄ charge separation, while the cross-linked structure enabled spatially the confined H₂O₂ activation. With 0.5 % PEI crosslinking identified as the optimal condition in the material fabrication, the composite achieved an exceptionally high H₂O₂ production rate and rapid atrazine degradation (k = 0.0234 min⁻¹), and efficient Fe²⁺/Fe³⁺ cycling with 96.05 % stability after four consecutive cycles. This study demonstrates an effective approach to simultaneously regulate charge separation and reaction pathways in photocatalytic-Fenton-like systems, offering a scalable solution for energy-autonomous water purification with less chemical inputs and recyclable catalytic components.