Catalyst Stability in Electrolytic Production of Hydrogen Peroxide: Importance, Challenges, and Standardized Degradation Protocols

Abstract

On-demand electrolytic hydrogen peroxide (H2O2) production is a significant technological advancement that offers a promising alternative to the traditional anthraquinone process.1,2 This method, which employs electrocatalysts to selectively reduce oxygen via two electrons transfers (ORR-2e–), has the potential to provide a sustainable and cost-effective method of producing H2O2. However, several challenges must be overcome in order to enable on-demand H2O2 electrosynthesis, including designing affordable and selective catalytic materials and preventing oxidative damage or degradation of catalytic materials.1,2 While catalyst development has traditionally focused on maximizing activity and selectivity, it is equally important to ensure that the catalysts maintain their performance over time in real-world applications. The stability of electrocatalysts is critical due to the harsh conditions they are subjected to during electrochemical reactions, such as high applied potential or currents, high temperatures, high pressures, and highly acidic or basic environments, as well as the oxidative power of H2O2 and reactive oxygen species that it can generate.3,4 If an electrocatalyst degrades or undergoes chemical changes during the reaction, it can result in reduced activity or selectivity, or even complete reaction failure. This not only leads to decreased yields and increased costs, but also poses potential safety hazards. The performance and degradation processes of catalysts can vary substantially depending on the reaction environment and the lineage of the catalyst used.3,4 In the last years, numerous classes of catalysts have emerged as highly active and selective for the electrocatalytic production of H2O2, especially transition metal-based materials and metal-free carbon-based materials.5 However, while numerous studies have focused on the activity and selectivity of catalysts for the ORR-2e–, research on their stability is still lacking. To effectively address the issue of catalyst material degradation under stress conditions and understand the underlying factors driving the degradation pathways, a unified and standardized approach is crucial. In this study, we focus on the deactivation processes in electrolytic H2O2 production and propose the use of specifically designed degradation protocols, employing a rotating ring-disk electrode setup. Our approach takes into account the most active and selective classes of catalyst for H2O2 production in acidic media, with the aim of enabling more researchers to tackle this crucial aspect and provide a comprehensive understanding and evaluation of the stability of electrocatalysts.