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

Abstract

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(WO 3 ), and Ni(Nb 2 O 5 ) 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 Nb 2 O 5 as the dispersed phase. The Ni(Nb 2 O 5 ) 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 H 2 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(Nb 2 O 5 ) catalyst.