Electrophoretically deposited 2D Ni–Fe LDH nanosheet thin films for enhanced oxygen evolution reaction activity

The compact stacked structure of layered double hydroxide (LDHs) restricts the exposure of the electrocatalytic active sites; thus, developing low-dimensional LDH nanomaterials with expanded surface area is crucial for oxygen evolution reaction (OER). Developing 2-D monolayers of LDH by liquid phase delamination can expose numerous active sites without changing their structure and composition. Here, we report an efficient and green way to synthesize delaminated nickel-iron-LDH nanosheets (NFL-NSs) and use them to deposit thin film OER electrocatalyst electrodes. The NFL-NSs thin film exhibits outstanding oxygen evolution performance in alkaline conditions compared to the bulk nickel-iron-LDH (NFL). The NFL-NSs thin film exhibits a low overpotential of 234 mV at a current density of 10 mA cm⁻² and outstanding electrode kinetics with a Tafel slope of 56.5 mV dec⁻¹. The electrochemical impedance (EIS) spectrum shows a lower charge transfer resistance of NFL-NSs (1.65 Ω) than NFL. Moreover, they display a high electrochemical active surface area (ECSA)S of 13.12 cm² and enhanced electrocatalytic stability during the chronoamperometric test of 24 h. The excellent catalytic stability demonstrated NFL-NSs electrodes are robust electrocatalysts. This article provides an efficient delamination method of LDHs to get cost-effective electrocatalysts for the OER with more active sites.