Enhancing the seawater hydrogen evolution performance of Ni-Cr-Fe-Mo heterojunctions using pore-forming agents

Direct seawater electrolysis is a pivotal technology for green hydrogen production. However, achieving efficient and stable hydrogen evolution reaction (HER) catalysts capable of operating efficiently and maintaining long-term stability at industrial-grade current densities remains a significant challenge. This work addresses this challenge by developing an efficient catalyst for alkaline/neutral seawater hydrogen evolution under industrial-grade current densities, fabricated via an elemental powder reaction synthesis method. Doping with Mo enabled the formation of hierarchical catalytic heterointerfaces and abundant multifunctional Mo and Ni active sites. The addition of the soluble pore-forming agent K₂CO₃ created a highly porous structure that fully exposes these active sites, thereby enhancing the overall catalytic activity. A synergistic catalytic effect at the heterointerfaces, achieved through a relay reaction pathway, not only facilitated charge transfer but also significantly improved the catalyst's long-term stability. Consequently, the catalyst demonstrated impressively low overpotentials of 121.8/120.8 mV to achieve 10 mA cm^-2 in alkaline/neutral seawater electrolytes, respectively. Furthermore, it maintained high activity with minimal voltage fluctuation for over 50 h at a high current density of 2000 mA cm^-2. The resulting Ni-Cr-Fe-Mo catalyst exhibits outstanding HER activity and remarkable long-term stability in both alkaline and neutral seawater electrolytes under ampere-level current densities. This work offers a feasible approach for developing efficient and stable catalysts for high-performance direct seawater electrolysis at industrial current densities.