Accelerating Electrode Optimization for Alkaline Water Splitting With SECCM And SEM/EDX for a Ni–Co Gradient Alloy

Abstract The growing demand for clean energy storage has driven extensive research into electrocatalysts for alkaline water electrolysis (AWE). In order to bring down the energy cost of the H2 produced by AWE, high-performance electrode materials are needed. Electrodes for this process are often engineered by combining several elements into alloy materials to optimize catalytic activity while maintaining cost-effectiveness. Therefore, developing a high-throughput methodology to accelerate electrocatalysts selection is highly desirable. Scanning electrochemical cell microscopy (SECCM) offers a powerful approach to this challenge, enabling microscale analysis of electrochemical activity across multiple regions of interest. However, methodologies to produce samples with substantial spatial heterogeneity matching the resolution of SECCM are lacking, especially for alkaline water splitting applications. Herein, a sample with graded composition was prepared to identify unambiguous correlations between local composition and catalytic activity. A Ni–Co alloy coating was deposited onto a Ni plate with controlled variations in Co content. A polished cross-section was analyzed by SECCM, enabling activity assessment over a range of Ni/Co ratios within a single experiment. The electrodeposition produced composition variations on a scale comparable to SECCM resolution. Catalytic activity increased with Co content (0–60%w/w) for both OER (with prior OH– and H2O adsorption) and HER, while the simultaneously assessed ORR activity showed the opposite trend. By extending it to other multicomponent alloys, this methodology can significantly accelerate the optimization of electrodes for alkaline water splitting.