Recent progress in electrochemical hydrogen sulfide splitting: Strategies for enabling Sulfur-tolerant anodic reactions

Abstract

Water splitting is widely recognized as the cleanest method for producing green hydrogen. Unfortunately, its efficiency is severely impeded by the sluggish oxygen evolution reaction (OER) occurring on the anode. In contrast, the electrochemical sulfide oxidation reaction (SOR) offers greater thermodynamic and kinetic ad-vantages. Combining the SOR with the hydrogen evolution reaction (HER) can permit hydrogen sulfide (H2S) splitting to simultaneously generate green hydrogen by lowering the energy input, mitigating environmental pollution, and recovering valuable sulfur compounds. This review provides a synopsis of recent developments in electrochemical H2S splitting, with a focus on the anodic electron transfer from sulfide to the anode via direct electrocatalysis or an indirect redox-mediated pathway. Attention has been paid to strategies that can mitigate the critical issue of poisoning caused by insoluble sulfur species formed during the SOR. Furthermore, recent advances in the development of active, robust, and sulfur-tolerant electrocatalysts and redox mediators that permit a stable SOR with resistance against sulfur-driven deterioration are explored. Finally, the current chal-lenges and future research directions of this highly promising but underexplored field are examined to encourage further research in this area.