Hydrogen iodide (HI) decomposition is an important part of thermo-chemical water-splitting sulfur-iodine (SI) cycle which can generate large amount of hydrogen without releasing green-house carbon dioxide gas. HI-decomposition is a very slow reaction even at a high temperature of 500°C. The use of catalyst in this reaction increases the reaction rate. So, a highly active and stable catalyst is desired from long time. Development of active and stable non-noble catalysts for HI-decomposition reaction is a significant challenge. Recent developments and trends in catalysis towards the catalyst synthesis, activity, and stability are discussed in this review. The activity, stability, and kinetic studies of different support materials, different monometallic and bimetallic catalysts are summarized here. The effect of preparation methods of catalysts on their activity and stability is also discussed. The high activity of catalysts for HI reaction is related to nanosize particles, metal dispersion, high specific surface area, oxygen vacancies (defects), and alloy formation between two metals. This article also summarized the different material of construction (MoC) used for HI reaction which are essential for building big pilot plants.

碘化氢（HI）分解是热化学水分解硫碘（SI）循环的重要组成部分，该循环可产生大量氢而不会释放温室二氧化碳气体。HI分解即使在500°C的高温下也是非常缓慢的反应。在该反应中使用催化剂提高了反应速率。因此，长期以来需要高活性和稳定的催化剂。开发用于HI分解反应的活性和稳定的非贵族催化剂是一项重大挑战。在这篇综述中讨论了催化剂在催化合成，活性和稳定性方面的最新进展和趋势。本文总结了不同载体材料，不同单金属和双金属催化剂的活性，稳定性和动力学研究。还讨论了催化剂的制备方法对其活性和稳定性的影响。HI反应催化剂的高活性与纳米级颗粒，金属分散体，高比表面积，氧空位（缺陷）以及两种金属之间的合金形成有关。本文还总结了用于HI反应的不同结构材料（MoC），这些材料对于建设大型中试工厂至关重要。