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 chiral structures and electrocatalytic activities remain a major challenge. Herein, chiral Co(OH)2 materials were prepared using the hydrothermal method and were examined for the oxygen evolution reaction (OER). By adjusting the amount of chiral L/D-threonine added during the synthesis, Co(OH)2 materials gradually changed from common hexagonal nanosheets to large-area willow leaf shapes with gradually enhanced circular dichroism signals. Theoretical calculations show that the introduction of threonine leads to a change in the growth direction of Co(OH)2 crystals to larger and thinner lamellar structures due to the difference in the adsorption energy of threonine on different crystalline surfaces of Co(OH)2. At the same time, the symmetry-breaking effect of surface-adsorbed chiral threonine leads to the twisting of lamellar structure to generate Co(OH)2 with chiral shapes. Compared to hexagonal Co(OH)2 nanosheets, optimized chiral Co(OH)2 nanomaterials exhibit improved OER performance, featuring a significant decrease of overpotential (η) by over 40 mV at the current density j = 10 mA cm−2 in 1.0 M KOH aqueous solutions. Theoretical calculations and experimental validation of the spin polarization show that chiral Co(OH)2 has a higher degree of spin state, reduces the adsorption energy of reaction intermediates in the OER process and increases the adsorption energy of by-product H2O2 intermediates, thus facilitating the formation of O2. This work carries significant implications for the controlled synthesis of transition metal-based chiral nanomaterials, as well as the influence of chirality on electrocatalytic OER.