Surface oxidation of commercial activated carbon with enriching carboxyl groups for high-yield electrocatalytic H₂O₂ production

Abstract

Two-electron oxygen reduction reaction (2e- ORR) for H2O2 production is regarded as a more ecologically friendly substitute to the anthraquinone method. However, the search of selective and cheap catalysts is still challenging. Herein, we developed a neutral-selective and efficient nonprecious electrocatalyst that was prepared from a commercial activated carbon (AC) by simply microwave-assisted ash impurity elimination and hydrogen peroxide oxidation for surface functional sites optimization. The oxygen configuration can be tuned with enriching carboxyl group up to 6.65 at.% by the dosage of hydrogen peroxide (mass ratio of H2O2/C=~0-8.3). Chemical titration experiments identified the carbonyl groups as the most potential active sites, with selectivity boosted by the additional carboxyl groups. The microwave-assisted moderate-oxidized activated carbon (MW-AC5.0) demonstrated optimal 2e- ORR activity and selectivity in neutral electrolyte (0.1 M K2SO4), with H2O2 selectivity reaching ~75%-97%, a maximum H2O2 production rate (1.90 mol·gcatal-1·h-1@0.1 V) and satisfying faradaic efficiency (~85 %) in gas-diffusion-electrode. When coupled with Fenton reaction, it can degrade a model organic pollutant (methylene blue [MB], 50 ppm) to colorless in a short time of 20 min, indicating the potential applications in the environmental remediation.

Tuning Ni3+ Content in Ni3S2 to Boost Hydrogen Peroxide Production for Electrochemical Synthesis

“…Electrochemical catalysts with redox properties can be categorized into three groups, including noble metals and their alloys, transition metal compounds, and metal-free carbon-based catalysts. , Some studies show that metal-based catalysts exhibit excellent redox properties, but their high cost and scarcity have hindered their widespread application. Carbon materials are abundant, cheap, and highly conductive, but their activity and selectivity for the production of H 2 O 2 are pretty low, and there is little room for improvement. − Transition metals have attracted our attention, and some studies have proved that inexpensive transition metal elements (e.g., Fe, Co, Ni, Mn, Cu, and Cr) have good redox activity due to their abundant multivalent states. − …”