Modular Hydrogen Peroxide Electrosynthesis Cell with Anthraquinone-Modified Polyaniline Electrocatalyst

Abstract

Advanced oxidation processes (AOPs) target the chemical destruction of a wide range of nonbiodegradable, toxic, and recalcitrant organic pollutants instead of removal via physical separation, which produces contaminant-laden concentrates or solids. Hydrogen peroxide (H2O2) is the most widely used precursor that produces a highly reactive and nonselective hydroxyl radical at the site of an AOP through activation by UV irradiation. The potential for AOPs to meet the growing demand of transforming a centralized treatment and distribution practice into a modular, small-scale, and decentralized treatment paradigm can be maximized by innovative technologies that can synthesize precursor chemicals also at the site of water treatment, eliminating the need for a continuous chemical supply. We here present an electrochemical H2O2 generation cell that produces a large quantity of H2O2 while consuming only 0.2 to 20% of the total electricity consumption of AOPs in various AOP application scenarios employing UV activation. We achieve high electrochemical H2O2 production efficiency by synthesizing an anthraquinone-modified polyaniline composite that enables an efficient two-electron oxygen reduction reaction. Polyaniline functions as a conductive support with abundant attachment sites, and anthraquinone ensures selective H2O2 generation. In a flow cell equipped with a gas diffusion cathode, H2O2 can be produced at a rate of 1.80 mol gcatalyst–1 hr–1 at 100 mA with a Faradaic efficiency of 95.83%. Finally, we examined the H2O2 production capability of the device with simulated drinking water and wastewater as feed electrolytes to demonstrate its potential for real-world operation scenarios.