High-Efficient Generation of H₂O₂ by Aluminum-Graphite Composite through Selective Oxygen Reduction for Degradation of Organic Contaminants

Abstract

Hydrogen peroxide (H₂O₂) is an effective green oxidant, which has been widely applied for environmental remediation. Here, we prepared a novel aluminum-graphite (Al-Gr) composite, which was capable of high-efficient production of H₂O₂ through selective O₂ reduction via a two-electron pathway. We discovered the production of H₂O₂ at a wide pH range, which could be enhanced by optimizing Al-Gr synthesis conditions. Poly(ethylene glycol) (PEG) addition could promote the formation of a welding interface and porous structure between Al and Gr in the Al-Gr composite, which enhanced the galvanic corrosion of Al⁰, the selectivity of oxygen reduction via the two-electron pathway, and the mass transfer of O₂ in the Al-Gr/O₂ system. The formation of Al₄C₃ could be regulated by sintering temperature and sintering time, which could promote the intergranular corrosion of Al⁰ and enhance the mass transfer of O₂ by reaction with water to generate the porous structure in the Al-Gr composite. The concentration of H₂O₂ reached 777.5 mg/L at an initial pH of 9.0, an Al-Gr dosage of 8 g/L, and an O₂ gas flow rate of 400 mL/min. The possible mechanisms of Al-Gr synthesis and H₂O₂ production in the Al-Gr/O₂ system were proposed. The Al-Gr composite was effective for the in situ production of H₂O₂, which could be further decomposed into a hydroxyl radical (^•OH) by Al⁰ in the Al-Gr composite. This composite could be used not only to decolorize the Rhodamine B dye but also to degrade various organic contaminants in different water matrices, indicating its environmental significance.