Advances and challenges toward efficient utilization of H2S for H2 production

H2S is an essential byproduct in refineries during the hydrodesulfurization process, serving as the largest sulfur resource in the industry. However, most of the H2S is processed with the two-step Claus Process, where the hydrogen is converted into water. As the development of the chemical industry creates growing energy demand and sustainability requirements, more efficient utilization of H2S to produce clean hydrogen and other value-added chemicals has attracted much research interest. Intending to bridge the gap between current research and industrial application, recent advances in thermo- and photocatalytic H2S decomposition are summarized based on strategies taken to alleviate their intrinsic restriction, thereby increasing single-run conversion. Thermal-based H2S decomposition is limited by its unfavorable thermodynamics, and this can be relieved or circumvented by shifting the equilibrium or implementing multistep reaction routes. Photocatalytic H2S decomposition is hampered by the photocatalysts' low stability and quantum efficiency, and surface modifications and electronic structure engineering have been applied to design novel photocatalysts. Future research directions are suggested to achieve more efficient H2S decomposition and more sustainable sulfur recovery.