Structure-Activity Correlation in Layered Double Hydroxides: Facilitating Oxygen Evolution through the Lattice Oxygen Mechanism

Abstract

A fundamental methodology for the sustainable generation of hydrogen is electrochemical water-splitting; however, the protracted kinetics of the oxygen evolution reaction (OER) diminish its efficacy. Conventionally, the OER pathway follows the adsorbate evolution mechanism (AEM), yielding elevated overpotentials. Recently, the lattice oxygen mechanism (LOM) has emerged as an alternative, wherein lattice oxygen atoms actively participate in O-O bond formation, thereby circumventing the constraints imposed by AEM. This investigation explores layered double hydroxides (LDHs) constituted of 3d-transition metals as a class of highly tunable and structurally versatile electrocatalysts that promote LOM. We scrutinize critical electronic structural descriptors, such as metal-oxygen covalency, oxygen vacancy density, d-band center alignment, and charge transfer energy, that govern lattice oxygen activation. Recent LDH-based systems have attained exceptional OER performance by the integration of defect engineering, heterostructure generation, anion/cation doping, and band modulation techniques, resulting in diminished overpotentials and improved stability in alkaline and saltwater environments. Inoperando spectroscopy investigations and density functional theory simulations furnish substantial mechanistic insights that bolster LOM pathways in these catalysts. This study presents a comprehensive review of LOM-driven OER in LDHs, accentuating pivotal principles, current accomplishments, and prospective trajectories in the advancement of robust and efficient electrocatalysts for green hydrogen production.