Electron density and CoFe-sites stability modulation of large-size CoFe layered double hydroxides by embedding low-crystallinity nickel hydroxides towards stable high-current water splitting

Ablation of well-defined nanostructures from continuous metal-sites leaching during catalysis is the cause of decreased catalytical activity/durability restricting the scale-up application in industry. Thus, it is essential to throw in-depth insight into the principle of metal-sites dissolution and structural features to tailor catalytical kinetics/stability. Considering layered double hydroxides (LDH) are haunted by unsatisfactory long-term catalytical stabilities, we lay emphasis on the nanostructure design of micrometer-scale-lateral-size CoFe LDH (1–3 μm) with embeddedness of low-crystallinity nickel hydroxides (LC-Ni(OH) 2 /CoFe LDH). Strong in-situ Ni leaching of LC-Ni(OH) 2 /CoFe LDH during catalysis enables the improved surface roughness and transition metal-site stabilization of CoFe LDH counterpart with optimized metal-oxygen covalency for stable ultrahigh-current (1000 mA cm −2 ) water oxidation . LC-Ni(OH) 2 /CoFe LDH exhibits excellent oxygen evolution reaction (OER) performance requiring only 270 mV overpotential to drive the current density of 100 mA cm −2 in 1 M KOH. More impressively, for 1000 mA cm −2 , its overpotential is only 346 mV with stable OER operation for 68 h. Density functional theory calculations reveal that the larger formation energy of oxygen vacancy in LC-Ni(OH) 2 /CoFe LDH inhibits the release of lattice O during OER catalysis, resulting the LC-Ni(OH) 2 /CoFe LDH excellent catalytical stability. This distinctive “corrosion-to-stabilization” perspective not only challenges the general belief that metal-site dissolution diminishes active phase to weaken the operation stability but also notably improves catalytic ability of LDH guiding practical catalysts design for commercial water splitting. • Large oxygen-vacancy formation energy during catalysis was achieved. • Inhibiting lattice-O release of CoFe LDH for OER renders high catalytical stability. • Low crystallinity Ni(OH) 2 was controllably embedded into CoFe LDH nanosheet.