Electrocatalytic splitting of hydrogen sulfide for simultaneous H2 production and sulfur recovery: A critical review of catalysts, electrolytes, and anti-passivation strategies

Electrocatalytic splitting of hydrogen sulfide (H 2 S) has emerged as a promising strategy for the simultaneous production of clean hydrogen and recovery of elemental sulfur, offering a thermodynamically advantageous alternative to water electrolysis while addressing the environmental and safety challenges posed by this toxic industrial byproduct. This critical review systematically examines the fundamental thermodynamic and kinetic principles governing direct and indirect electrochemical H 2 S conversion pathways, with particular emphasis on sulfide oxidation reaction (SOR) mechanisms at the anode and hydrogen evolution reaction (HER) at the cathode. Advances in electrocatalyst design including transition metal sulfides, selenides, phosphides, heterostructures, and bifunctional architectures are evaluated alongside anti-passivation strategies, electrolyte systems (aqueous alkaline/acidic, ionic liquids, and non-aqueous), membrane technologies, and diverse cell configurations. Despite significant progress in activity and stability under idealized conditions, critical gaps persist in long-term durability against sulfur passivation, selectivity control, scalability under realistic industrial feeds, and integration into practical systems. By highlighting these limitations and proposing future directions in computationally guided catalyst discovery, operando characterization, and reactor engineering, this review aims to accelerate the transition of H 2 S electrolysis toward industrial viability.