Engineering dual MoC–Mo₂C heterostructure–knotted CNTs for efficient direct seawater electrolysis

Considering the abundant reserves of seawater and limited resources of freshwater, seawater electrolysis is a more economically competitive technology for producing high-purity hydrogen, but remains a challenging approach. Herein, we report an innovative strategy for constructing dual MoC–Mo₂C heterostructure–knotted CNTs nanorods (MoC–Mo₂C/CNTs) to improve the electrocatalytic performance and durability in alkaline seawater, in which the hybrid electrode achieves 10 mA cm⁻² at low overpotentials of 95 and 279 mV for HER and OER, respectively. For overall simulated and natural seawater splittings, a low cell voltage of 1.57 and 1.61 V, respectively, is necessary to drive 10 mA cm⁻² and outstanding durability over 50 h at a high current density of 50 mA cm⁻². The experimental results indicate that the unique boundary interface of MoC–Mo₂C/CNTs could result in rich exposed active sites, corrosion resistance layer, and electronic redistribution, thus leading to high-performance HER and OER activities. This work provides an ultimate approach to the rational design of multi-component transition metal carbide-based heterogeneous electrocatalysts for seawater electrolysis.