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.