Directed electron transport induced surface reconstruction of 2D NiFe-LDH/Stanene heterojunction catalysts for efficient oxygen evolution

As promising non-noble candidates for oxygen evolution reaction (OER), NiFe-based layered double hydroxides (NiFe-LDH) has been proven to transform into its high-oxidation-state Ni/Fe oxyhydroxide, which act as the primary active sites. However, advancing the emergence of high-oxidation-state Ni/Fe oxyhydroxide during OER process currently remains a challenge. Herein, a novel 2D NiFe-LDH/stanene p-n junction catalyst is achieved by inserting stanene between NiFe-LDH and Ni foam. In-situ Raman spectra and density functional theory calculations (DFT) confirm that stanene not only benefits for the construction of built-in electric field, but also serves as an electron absorber to induce a directed electron transport from Ni, Fe to Sn, which thus facilitates the surface reconstruction to form the catalytically active Ni/FeOOH. Consequently, an ultralow OER overpotential (230 mV) at 100 mA cm-2 is achieved, corresponding to a considerable decrease of 22.3% and 42.1% compared with the individual NiFe-LDH and stanene, respectively. This work provides a promising avenue for the development of efficient OER catalysts for water electrolysis.