Indirect electrocatalytic decomposition of hydrogen sulfide into hydrogen and sulfur using cobalt doped cadmium sulfide

The hydrotreating process in refineries generates substantial toxic H2S gas. While the conventional Claus process (partial oxidation of H2S) recovers sulfur, it fails to utilize the hydrogen resource in H2S. Electrocatalytic decomposition of H2S to produce high-purity H₂ (for refinery hydrogenation cycles) and sulfur offers significant circular economy benefits. However, traditional direct electrocatalytic systems suffer from low efficiency, severe membrane fouling (due to sulfur deposition blocking ion-exchange membranes), and high catalyst costs, hindering the development of H2S decomposition technologies. To address these challenges, we developed an efficient indirect electrocatalytic H2S decomposition system using Co-doped CdS materials (Co-CdSm, Co:Cd ≈ 1-5:1-5) as the electrocatalyst. Experimental results demonstrate that the optimized Co-CdSm (4:1) catalyst achieves exceptional H2S decomposition performance, requiring a low onset potential of 1.25 V vs. RHE to drive the reaction, with 99% conversion efficiency, 60-hour stability, and 98% H2 Faraday efficiency. Theoretical calculations quantify the adsorption/dissociation processes of H2S on CdS and Co-CdSm, revealing that Co sites effectively reduce the reaction energy barrier and efficiently decompose H2S into H2 and sulfur.