Selective Suppression of Water Oxidation Enables Nucleophilic Small-Molecule Oxidation on Mn-NiAl Layered Double Hydroxides for Low-Voltage Hydrogen Generation

Abstract

Selective anodic electrocatalysts that promote small-molecule nucleophilic oxidation reactions (NORs) in place of the sluggish oxygen evolution reaction (OER) are essential for energy-efficient hydrogen production. Here, a series of Mn-incorporated NiAl layered double hydroxides (Mn x Ni 1-x Al-LDHs) with systematically tuned Mn to Ni ratios were synthesized via a coprecipitation route and evaluated as anodic electrocatalysts for NORs in alkaline media.Structural and spectroscopic analyses confirm successful Mn incorporation into the NiAl-LDH lattice without detectable secondary phases. Electrochemical studies show that Mn incorporation modulates anodic reactivity by regulating redox accessibility and surface hydroxide interactions, thereby enabling selective small-molecule oxidation under conditions where OER is typically dominant. At 100 mA cm -2 , the optimized Mn 10.0 -NiAl-LDH requires 1.607 V for OER, whereas NORs proceed at substantially lower anodic potentials (1.588-0.042 V), depending on the substrate. This selective anodic behavior is attributed to Mn-induced tuning of the local electronic structure and redox accessibility, together with regulated surface hydroxide interactions that accelerate interfacial charge transfer for nucleophilic oxidation. Overall, a clear compositionactivity-selectivity relationship is established, positioning Mn-incorporated NiAl-LDHs as a costeffective anodic platform for low-voltage, small-molecule-assisted hydrogen generation and providing design guidance for selective transition-metal electrocatalysts.