Chirality engineering in layered metal hydroxides for enhanced electrocatalytic oxygen evolution and reaction mechanism revelation

Abstract

Inorganic chiral nanomaterials are promising electrocatalysts for energy-related small-molecule activation reactions. However, designing new chiral nanomaterials and exploring the relationship between their chiral structures and electrocatalytic activities remain major challenges. Herein, chiral Co(OH)₂ materials were prepared using a hydrothermal method and were examined for the oxygen evolution reaction (OER). By adjusting the amount of chiral L-/D-threonine added during synthesis, the morphology of Co(OH)₂ gradually changed from common hexagonal nanosheets to large-area, willow leaf-like shape, accompanied by gradually enhanced circular dichroism signals. Theoretical calculations show that the introduction of threonine alters the crystal growth direction of Co(OH)₂, leading to the formation of larger and thinner lamellar structures due to differences in the adsorption energies of threonine on different crystalline surfaces of Co(OH)₂. At the same time, the symmetry-breaking effect of the surface-adsorbed chiral threonine leads to the twisting of the lamellar structure to generate Co(OH)₂ with chiral shapes. Compared with hexagonal Co(OH)₂ nanosheets, the optimized chiral Co(OH)₂ nanomaterials exhibit improved OER performance, with a significant decrease in overpotential (η) of over 40 mV at a current density of j = 10 mA cm⁻² in a 1.0 M KOH aqueous solution. Theoretical calculations and experimental validation of spin polarization show that chiral Co(OH)₂ has a higher degree of spin state, which reduces the adsorption energy of OER intermediates and increases the adsorption energy of the H₂O₂ by-product, thus facilitating O₂ formation. This work provides guidance for the controlled synthesis of transition metal-based chiral nanomaterials and clarifies how chirality influences the electrocatalytic OER.