Interfacial built-in electric field in 2D Ni(OH)2 heterojunction with the sodium organic compound for enhanced oxygen evolution catalysis

• The introduction of SDS modulates the coordination environment of nickel hydroxide nanosheets. • The OER kinetic process is accelerated by the presence of built-in electric field. • Abundant catalytic sites and rapid electrolyte transport facilitate the process. Oxygen evolution involves a complex four-electron transfer process with sluggish reaction kinetics which leads to large cell voltages, limiting the practical applications of electrochemical hydrogen production. Driven by the urgency to design and develop highly efficient OER catalysts to improve the efficiency of water electrolysis, transition metal hydroxides are promising candidates due to their tunable OER catalytic properties. However, their intrinsic activities are hindered by poor electrical conductivity and insufficient mass transfer capability. In this study, we tune the coordination environments of central species in two-dimensional (2D) ultrathin Ni(OH) 2 nanosheets with sodium dodecyl sulfate (SDS). This heterojunction features an interfacial built-in electric field (BEF) that modulates the electronic structure, bringing the d-band center of Ni closer to the Fermi energy level. This adjustment enhances electron transfer and optimizes oxygen intermediate adsorption, improving OER kinetics. Additionally, the 2D morphology and abundant porosity provide rich catalytic sites and facilitate fast electrolyte transport. Therefore, the 2D Ni(OH) 2 -SDS heterojunction demonstrates remarkable OER activity, with a low overpotential of 285 mV and a Tafel slope of 68 mV dec -1 at a current density of 10 mA cm −2 . This work offers a novel strategy for manipulating the coordination environment and electronic structure in metal hydroxides and presents a new model for the rational selection of hetero-components in OER electrocatalysis.