Corrosion engineering approach to rapidly prepare Ni(Fe)OOH/Ni(Fe)Sx nanosheet arrays for efficient water oxidation

Abstract

The Ni–Fe composite catalyst has received in-depth research attention due to high intrinsic activity in electrochemical water splitting applications. Corrosion engineering is considered an effective strategy for preparing large-scale Ni–Fe composites to match industrial electrocatalytic electrolyzers. Here, we demonstrate an efficient corrosion strategy to prepare defect-rich Ni(Fe)OOH/Ni(Fe)S_x nanosheet arrays on a NiFe foam within 10 min. The corrosion solution we proposed (containing (NH₄)₂S₂O₈, (NH₂)₂CS, and FeCl₃) has strong oxidizing properties, which releases a large amount of heat when it corrodes the Ni–Fe foam. The heat promotes the hydrolysis of (NH₂)₂CS and creates an alkaline environment for the rapid growth of Ni–Fe composites. Experimental results reveal that Ni(Fe)S_x plays a crucial role in enhancing the oxygen evolution reaction performance of Ni(Fe)OOH/Ni(Fe)S_x. Therefore, Ni(Fe)OOH/Ni(Fe)S_x exhibits remarkable catalytic activity with low overpotentials of 227 and 313 mV to afford current densities of 10 and 1000 mA cm⁻², respectively. Under 270 mV overpotential, the intrinsic catalytic activity of Ni(Fe)OOH/Ni(Fe)S_x is 24.65-fold, 21.09-fold, and 52.21-fold that of FeOOH/FeS_x, NiOOH/NiS_x, and Ni(Fe)OOH, respectively. Moreover, large-scale Ni(Fe)OOH/Ni(Fe)S_x electrode materials are prepared with a size of 10 × 10 cm² on a NiFe foam, implying the huge potential for practical applications. This work offers a new perspective on designing large-scale and highly active oxygen evolution catalysts.