Ultra-durable high-performance CoMo-MCA/Fe-NWs/NF heterostructures for industrial-grade current density seawater splitting

Abstract

Extensive efforts are being dedicated to developing high-performance electrocatalysts for water splitting to achieve efficient and stable hydrogen production, especially under high current densities. In this study, we synthesised a CoMo microcolumn arrays (MCA)/Fe-nanowires (NWs)/nickel foam (NF) catalyst through a simple yet effective combination of hydrothermal and solution-based methods. This catalyst exhibits remarkable performance during the oxygen evolution reaction (OER), achieving a low overpotential of 425 mV at a current density of 2000 mA cm⁻² and maintaining stability for 200 h at a current density of 1000 mA cm⁻² in 1 M KOH. In natural alkaline seawater, the catalyst demonstrates an overpotential of 464 mV at a current density of 1000 mA cm⁻², with stability extending to 250 h at a current density of 500 mA cm⁻². These overpotentials are lower than that required for hypochlorite production (>490 mV). Furthermore, during alkaline full seawater splitting, the synthesised catalyst delivers a cell voltage of 1.861 V at a current density of 1000 mA cm⁻², sustaining stability for 100 h at a current density of 500 mA cm⁻². The heterointerfaces in the CoMo-MCA/Fe-NWs/NF structure optimise the electronic configuration, enhancing OER activity. The MCA structure and Fe₂O₃ NWs increase the electrochemically active surface area, providing numerous active sites and ensuring long-term durability under harsh conditions. This study suggests a promising approach for industrial-scale seawater electrolysis by engineering effective heterostructures and interfacial active sites.