In situ generation of hydrogen peroxide using a schwertmannite/nickel foam catalyst for enhanced heterogenous Fenton degradation of dye wastewater

Abstract

Conventional Fenton processes face challenges such as the need for external hydrogen peroxide (H₂O₂) addition, leading to low oxidant utilization efficiency, high costs, and safety risks. To address these limitations, a novel heterogeneous Fenton catalyst was fabricated by supporting schwertmannite (Sch) on nickel foam (NF) for the degradation of Rhodamine B (RhB). This system enables the in situ generation of H₂O₂ through an oxygen reduction reaction (ORR) pathway on the NF substrate. Under optimized conditions (20 mg L⁻¹ RhB, pH 2.0, 180 rpm), the Sch/NF composite achieved 99% RhB decolorization within 15 min. Quenching experiments and electron paramagnetic resonance analyses identified hydroxyl radicals (˙OH) and singlet oxygen (¹O₂) as the dominant reactive species. The enhanced catalytic performance is attributed to the accelerated Fe²⁺/Fe³⁺ cycling, facilitated by electron donation from the Ni/Ni²⁺ redox couple within the NF support. This synergy enables the continuous regeneration of Fe²⁺ sites, which subsequently activate the in situ generated H₂O₂ to produce radicals. This work provides a feasible strategy for constructing high-performance, self-sustaining heterogeneous Fenton catalysts for efficient dye wastewater treatment.