Amorphous heterojunction and fluoride-induced effects enable a F-Ni(OH)2/Ni–B electrocatalyst for efficient and stable alkaline freshwater/seawater hydrogen evolution at a high current density

Abstract

The search for efficient, robust, and cost-effective catalysts for the hydrogen evolution reaction (HER) is highly desirable. However, the development of freshwater/seawater electrolysis for hydrogen production as a viable energy conversion technology remains a challenge. Herein, a fluorine-doped Ni(OH)₂/Ni–B amorphous heterostructure (FNH/NB) was synthesized via simple hydrothermal, electroless plating, and alkaline etching methods. Our designed experiments demonstrate that the as-prepared catalyst benefiting from amorphous interfacial coupling and F-induced effects exhibits accelerated H₂O dissociation kinetics and optimized adsorption of intermediates. As a result, the FNH/NB catalyst shows high alkaline HER activity, requiring low overpotentials of 23, 28, and 30 mV to drive a current density of 10 mA cm⁻² in alkaline freshwater, simulated seawater, and real seawater, respectively. Particularly, the stability of the designed catalyst is effectively improved using a fluorine doping strategy. Specifically, FNH/NB could maintain excellent electrocatalytic performance over 50 hours at current densities of 10 and 1000 mA cm⁻² in an alkaline solution containing KF. The current work reveals the superiority of integrating F doping and amorphous heterostructure engineering in developing efficient and robust catalysts.