Novel hydrothermal electrodeposition to fabricate mesoporous film of Ni_0.8Fe_0.2 nanosheets for high performance oxygen evolution reaction

Here, we report a new synthetic strategy to fabricate mesoporous film of Ni_0.8Fe_0.2 nanosheets for high performance oxygen evolution reaction (OER). Mesoporous Ni_0.8Fe_0.2 film self-supported on stainless steel mesh (SLS) was prepared via a novel hydrothermal electrodeposition process. Hydrothermally driven electrodeposition method showed significant advantages toward OER: (1) high temperature makes H₂ generated on the cathode to overflow faster. Both the gas generated on the cathode and hydrothermal condition impacted coating surface, hence, the film possessed more active sites to improve OER properties and (2) hydrothermal condition improved the crystallization of the coating leading to excellent electrode stability under OER test. The mesoporous Ni_0.8Fe_0.2 film exhibited an overpotential of 206 mV at 10 mA cm⁻² (i.e., 1.436 V vs. RHE), a Tafel slope of 64 mV dec⁻¹ and excellent stability after 2 × 10⁵ s (more than 55 h) at 10 mA cm⁻². The superior OER properties could be attributed to the film's novel synthetic process, porous structure and high electrical conductivity. This work shows a new strategy to fabricate mesoporous alloy films as OER catalysts.