Nickel–iron layered double hydroxide (NiFe-LDH) is a promising non-noble electrocatalyst for the oxygen evolution reaction (OER) in anion exchange membrane (AEM) water electrolysis. However, its practical application is largely hindered by impurity introduction from conventional pH adjustment, unclear magnetic field regulation mechanisms, and insufficient activity under industrial current densities. Here, we report a clean and controlled strategy. The pH of the soaking solution was controlled by controlling the ratio of nitrogen to oxygen during the process of mixing the soaking solution (gas ratio–mediated pH control). The magnetic field was added in combination with the test phase, to optimize the OER performance of the electrode. Regulation of the O 2 /N 2 mixing ratio enables impurity-free pH tuning of the reaction solution and yields a uniform petal-like layered structure with abundant active sites. Meanwhile, the research on the magnetic field has revealed the interrelationships between the magnetic field and the substrate structure, the intrinsic catalytic activity, and the morphology of the catalytic layer. As a result, the optimized NiFe-LDH/NF electrode exhibits acceptable and stable OER activity with an overpotential of 402 mV at 1000 mA·cm -2 and satisfactory durability for 80 h at 500 mA·cm -2 . When applied in AEM electrolyzers, it shows reliable long-term stability for over 100 h at an industrial-level current density of 8000 A·m -2 and a comparable cell voltage relative to commercial electrodes, with a voltage difference of up to 351 mV. Experimental results confirm that gas-ratio-mediated pH control avoids impurity contamination and stabilizes phase composition, while the magnetic field provides a reliable screening principle for multi-field coupled electrocatalysts. This work clarifies the key roles of gas-ratio-mediated solution pH regulation and magnetic field screening in boosting the OER performance of NiFe-LDH electrodes, which provides new insights for designing low-cost and practically applicable electrocatalysts for industrial AEM water electrolysis.
Zhou et al. (2026) studied this question.