Critical insights from alloys and composites of Ni-based electrocatalysts for HER on NaCl electrolyte

It is critical to minimize the cost of materials and inputs used in hydrogen production and to create solutions for large-scale generation to reduce the cost of hydrogen produced. Seawater is a natural low-cost electrolyte with high Na+ and Cl- concentrations, among other soluble salts. Chloride ions allow a highly corrosive media to the materials typically used as electrodes. In this work, we have prepared and tested different Ni-based catalysts for hydrogen evolution in NaCl-containing solutions. NiMo alloy, Ni(WO3), and Ni(Nb2O5) composites are compared and studied from a critical point of view to find a viable solution for catalysis in seawater electrolysis. The NiMo catalyst presents a higher dissolution rate in the NaCl medium than all synthesized catalysts. Furthermore, Ni-based composites showed improved durability due to a decrease in dissolution, and an increase in catalytic activity when using Nb2O5 as the dispersed phase. The Ni(Nb2O5) electrodes presented the higher catalytic activity in NaCl solution, even higher than that found in NiMo catalyst. •Different strategies for the synthesis of catalysts for the electrogeneration of H2 in NaCl electrolyte are analysed.•NiMo catalyst presents higher dissolution in the NaCl medium than the composite synthesized catalysts.•The use of composites improves the catalyst durability, reducing the dissolution.•A remarkable increase of the current density was found when using the Ni(Nb2O5) catalyst.