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.