A review on factors and components of CWSE for hydrogen production

The pursuit of carbon neutrality and peak carbon emissions necessitates the development of hydrogen energy. Among the various hydrogen production technologies, coal water slurry electrolysis (CWSE) stands out due to its reduced total electricity consumption, which is only 1/3–1/2 of that of traditional water electrolysis. However, CWSE faces significant challenges in terms of low efficiency and instability, hindering its industrialization. To address these issues and explore potential pathways for efficiency enhancement and feasibility improvement, this review presents a comprehensive analysis of the current research and progress in CWSE compared to traditional water electrolysis. The impact of various components and factors, including catalysts, electrode materials, electrolysis voltage, coal pretreatment, coal particle microstructure, reaction temperature, sulfuric acid concentration, CWS stirring rate, and additional catalysts, on CWSE hydrogen production is thoroughly discussed. Furthermore, critical issues such as understanding the electrolysis mechanisms, increasing hydrogen production efficiency and reaction rates, and reducing energy consumption and carbon emissions (through carbon capture, utilization, and storage: CCUS) are addressed. Special attention is given to the interface design, including ion and proton exchange membranes, and electrodes. A SWOT analysis of CWSE is conducted to highlight its strengths and limitations, with future directions and technological prospects outlined. Additionally, this review emphasizes the interrelated characteristics between renewable energy integration, electrode and membrane material optimization, supercritical carbon dioxide (SC-CO₂) recovery in conjunction with CCUS, and SC-CO₂ medium jet technologies. Overall, this review promotes an in-depth exploration of the CWSE mechanism and advances technology strategies for large-scale applications, contributing to the development of sustainable hydrogen production technologies.