Self-Supported 3D NiCrP-NiP Sponge Electrode for Corrosion-Resistant and Long-Term Seawater Electrolysis

The development of efficient and stable bifunctional electrodes for hydrogen production from seawater electrolysis poses a significant challenge, primarily due to the difficulty in mitigating chloride ion corrosion. In this work, an “integrated” nickel–phosphorus (NiP) and NiCrP heterostructure (NiCrP-NiP@PU) is successfully constructed on a nonconductive polyurethane (PU) sponge via a mild electroless plating method with chromium (Cr) modulation to enhance the electrocatalytic activity and corrosion resistance. The in situ growth catalytic electrode has the flexible characteristics of bending, folding, and deformation, and can adjust its rigid characteristics of bending and compression, replacing the commercial nickel foam catalytic electrode. Benefiting from the Cr-optimized electronic structure optimization endowed NiCrP-NiP@PU with superior electrocatalytic activity, achieving 100 mA cm–2 for hydrogen/oxygen evolution reaction (HER/OER) with overpotentials as low as 131 and 350 mV in simulated seawater (1.0 M KOH + 0.5 M NaCl). In simulated seawater and real seawater, it operates stably for more than 1500 h with an industrial-grade high current density of 500 mA cm–2 and achieves excellent seawater corrosion resistance. Based on the excellent electrocatalytic activity and stability at industrial-grade current of the NiCrP-NiP@PU electrode, efficient water electrolysis for hydrogen production is realized using an anion exchange membrane (AEM) electrolyzer. The present work provides an economical, mild, and tunable strategy to realize the in situ growth of phosphorus-based catalysts on nonconducting substrates for efficient and stable seawater splitting, which is expected to be widely applied in seawater electrolysis for hydrogen production.