Advancing hydrogen peroxide electro-generation: Selective production at high rates in a flow-through module

Abstract

Electrochemical synthesis of hydrogen peroxide (H₂O₂) via oxygen reduction reactions (ORR) represents a green, environmentally friendly, and decentralized alternative to the conventional, fossil-based, and centralized anthraquinone process. This work presents a flow-through module using commercial carbon black (CB) as a catalyst at current densities of up to 120 mA cm⁻². Acid treatment of CB increases its oxygen content, leading to Faraday efficiency (FE) values above 80 % with a maximum specific H₂O₂ production rate of 64.3 mg cm⁻² h⁻¹. Additionally, the effect of catalyst loading on the functionality of a gas diffusion electrode (GDE) at 120 mA cm⁻² and over long-term electrolysis (7.5 h) is investigated, discussing the detrimental penetration of electrolyte into the GDE due to the enhanced electro-wetting, which shifts the three-phase boundary toward the gas channel side. This study underscores the critical significance of optimizing the parameters involved in GDE fabrication, especially under high current densities and extended operational periods, propelling our understanding toward the development of a robust flow-through module for the electro-generation of H₂O₂.