Research progress on metal oxide oxygen carrier materials for two-step solar thermochemical cycles in the last five years

In the evolving landscape of sustainable energy solutions, the approach of two-step solar thermochemical cycles assumes a position of paramount importance. Metal oxide oxygen carriers, integral to the functioning of these cycles, play a pivotal role in harnessing solar energy for the production of CO and H₂ through two-step chemical reactions involving the reduction and oxidation of metal oxides. This review article serves as a comprehensive exploration of state-of-the-art developments in metal oxide oxygen carriers within the realm of two-step solar thermochemical cycles. It meticulously evaluates a wide range of materials, spanning both volatile and non-volatile varieties, with a keen focus on critical parameters, including fuel yield, cycle stability, reaction conditions, and reaction mechanisms. Furthermore, it delves into the future material development prospects, shedding light on the path forward for advancing sustainable energy technologies.