Transition metal-based layered double hydroxides (LDHs) have gained an attractive interest among two-dimensional (2D) materials because they offer tunable structure, abundant active sites, and superior stability for carbon-dioxide (CO2) reduction. Recently, defect engineering, particularly transition metal vacancies, acted as the most important defects in enhancing the bifunctional catalytic activity of LDHs both in photocatalysis and electrocatalysis. This review explores the critical role that transition metal vacancies and defects play in improving CO2 adsorption, activation, and charge transfer processes, which in turn enhance catalytic performance. The interaction between defect engineering and LDHs electronic structure is examined, providing insight into the processes that support multi-electron transfer pathways and stabilize reaction intermediates. Furthermore, generating defects in layered double hydroxides and advanced spectroscopic techniques such as XAS, ESR, and PAS for defect-driven catalytic behavior are discussed. This review demonstrates the ground-breaking potential of defect-engineered LDHs in creating sustainable, dual-functional catalytic systems for CO2 reduction by tackling the problems of stability, scalability, and defect control. The insights provided in this review aim to inspire innovative approaches for the design of next-generation catalysts, paving the way for effective carbon capture and conversion technologies.
SL et al. (Sun,) studied this question.