Photocatalytic Oxidative Desulfurization of H2S: A Review of Photocatalysts, Reaction Mechanisms, and Future Perspectives

Hydrogen sulfide (H2S) is a highly toxic, corrosive, and malodorous sulfur-containing pollutant emitted from diverse industrial and agricultural activities. Its low concentration, dispersed distribution, and intermittent emission characteristics often limit the effectiveness and economic feasibility of conventional desulfurization technologies. Photocatalytic desulfurization has emerged as a promising approach for H2S removal owing to its ability to utilize light energy under ambient conditions without generating secondary pollution. Among the various photocatalysts investigated, TiO2 remains the most extensively studied material. To improve photocatalytic performance, strategies such as elemental doping, defect engineering, heterojunction construction, and support coupling have been widely adopted to enhance visible-light absorption, promote charge separation, and improve resistance to deactivation. In addition, emerging photocatalysts, including metal–organic frameworks (MOFs), graphitic carbon nitride (g-C3N4), conjugated polymers, and carbon-based composites, have shown considerable potential for improving H2S adsorption, activation, and visible-light utilization. Photocatalytic H2S oxidation generally proceeds via sulfate or elemental sulfur formation pathways; however, both can result in sulfur accumulation on catalyst surfaces, leading to performance deterioration. Consequently, developing photocatalytic systems with efficient solar-light utilization, high sulfur tolerance, and long-term operational stability remains a critical challenge. This review summarizes recent advances in photocatalytic H2S oxidation, focusing on photocatalyst design, H2S removal performance, reaction mechanisms, and catalyst deactivation behaviors. Future challenges and research directions for the development of efficient and durable photocatalytic desulfurization technologies are also discussed.