Lattice Strain-Induced D-Band Modulation in Nanosheets of Cu_<i>x</i>NiCo-Layered Double Hydroxides for Enhanced Water Electrolysis

Abstract

Understanding the role of strain in modifying a material’s properties is becoming crucial for realizing its usefulness in energy storage and conversion applications. Inducing lattice strain by doping with metal atoms is emerging as a new strategy for boosting the performance of 2D nanomaterials. This strategy needs to be carefully investigated for layered double hydroxides (LDHs) and similar 2D nanomaterials, especially in the field of water electrolysis. In this study, it is demonstrated that metal doping-induced lattice strain enhances the binding strength for reactive species adsorption by shifting the metal d-band center closer to the Fermi level. This improves the CuxNiCo-LDH’s ability to bind reactive intermediates on to its surface, leading to improved rate kinetics for both hydrogen evolution reaction (HER)/oxygen evolution reactions (OER) compared to pristine NiCo-LDH catalysts. The inferences are corroborated by the conventional volcano plot to explain the electrocatalytic activity of Cu-doped LDHs for HER/OER reactions. Density functional theory calculations unequivocally confirm the experimental results. Cu1NiCo-LDH exhibits the lowest overpotential and Tafel slope in both three-electrode and two-electrode (full-cell) configurations, aligning with the theoretical observations. Therefore, it is established that lattice strain-derived d-band modulation can be considered as a descriptor for developing new nanostructured LDH-based catalysts for cost-effective and industrially viable water electrolysis.