Built-In Electric Field in 2D/2D LDH/Antimonene Heterostructure to Induce Stable β-NiOOH at Ultralow Potential for Cost-Effective Water Electrolysis

Abstract

NiFe-LDH is regarded as one of the most efficient oxygen evolution catalysts, with the catalytic activity stems from the in-situ formation of NiOOH active phase induced by anodic polarization. In the reaction, NiFe-LDH initially reconstitutes into highly active β-NiOOH phase, which is difficult to initiate and stabilize at low potential, and will be irreversibly transformed into less activity γ-NiOOH phase due to over-oxidation. In this work, a novel built-in electric field (BEF)-driven surface reconstruction strategy is proposed to reduce the potential required for β-NiOOH formation and prevent its over-oxidation. This is demonstrated in a two-dimensional NiFe-LDH/Antimonene (2D/2D NiFe-LDH/AMNSs) heterostructure catalyst, where a strong BEF is generated through work function engineering. Kelvin probe force microscopy (KPFM) tests, in-situ Raman spectra and theoretical calculations confirm that the BEF enhances electron transfer at the NiFe-LDH/AMNSs interface, creating a local potential that reduced the applied potential by 80 mV for formation of β-NiOOH from NiFe-LDH. Consequently, a record-low overpotentials of 144 and 209 mV are achieved at 10 and 300 mA cm⁻² for oxygen evolution reaction (OER), making it the best-performing NiFe-LDH based catalysts to date. It also demonstrates excellent durability and hydrogen evolution reaction (HER) activity, making it ideal for overall water splitting.