Strategies to maximize the oxygen evolution reaction in layered double hydroxides by electronic defect engineering

Layered double hydroxides (LDHs) have emerged as highly promising oxygen evolution reaction (OER) catalysts because of their naturally forming two-dimensional (2D) layer structure and intrinsic oxygen vacancies. Numerous efforts to develop synthesis methods as well as modify the structure and composition of LDHs have helped to improve their electrocatalytic performance. Recent strategies to optimize LDHs have gone beyond regulating oxygen vacancies via metal modifications, with innovative ideas of atomic loading and anion-based lattice modification being proposed. In this review, a fundamental understanding of the structural design and its close relationship with the OER mechanism in alkaline media are discussed. Based on the inherent defects and structural characterization of LDHs at an atomic scale, novel progress in promoting OER development activity is summarized, including heteroatomic doping, intercalation, composite construction and single-atom loading. Furthermore, the concept of heteroatoms as electronic defects is emphasized, with the regulation mechanism behind these elucidated by summarizing recent advances in LDHs as highly active OER catalysts. Finally, key challenges to further optimize performance in LDHs catalyst by overcoming the bottleneck of the scaling relationship, expansion of active components and preparation of functionalization, shed light on future research and development directions.