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

NADIA B. YSEA; VICTORIA BENAVENTE LLORENTE; ANTONELLA LOIÁCONO; LUCRECIA LAGUCIK MARQUEZ; GABRIELA I. LACCONI; ESTEBAN A. FRANCESCHINI

Mar del Plata

Encuentro; 34th Topical Meeting (TM) de la Sociedad Internacional de Electroquímica (ISE); 2023

ISE

The hydrogen produced by the electrolytic route is made at a high cost, which contributes to maintaining dependence on fossil fuels. One of the ways to reduce the cost of the hydrogen produced is to reduce the cost of the materials and supplies used in its production, for example, by using seawater instead of alkalinized ultrapure water [1,2]. In this work, we analyze from a critical point of view two different strategies for the synthesis of catalysts for hydrogen generation in NaCl solution using a NiMo alloy catalyst, similar to those presented in the literature, and comparing it with the chemical, electrochemical parameters and structural by using pure nickel catalysts, Ni(WO3) and Ni(Nb2O5) composites. These compounds were selected for having excellent properties in conventional alkaline media. In this way, we compare the catalysts and analyze the real effects that lead to obtaining a good catalytic activity and durability of the materials. Figure 1: a) Cyclic voltametries measured at 0.005 V s-1 b) Chronoamperometric profiles for each catalyst measured at – 1.5 V vs SCE in 3.43% w/V NaCl aqueous solution at 298 K.It has been found that the materials obtained have higher catalytic activities than the nickel catalyst obtained using the Watts bath (Figure 1). It is important to consider that the reason for the higher current density of the catalysts is due to the increase in the electrochemically exposed area, as indicated by the measurements of the roughness factor and double-layer capacitance. On the other hand, the NiMo catalyst presents a high dissolution in the highly corrosive NaCl medium. Although all the catalysts, including conventional nickel, present a slow corrosion even during the application of the reducing potential. It has been proven that the strategy of using composites improves the durability of the catalyst, reducing dissolution and, particularly when Nb2O5 is used as the dispersed phase, the catalytic activity (normalized by geometric area) and the durability of nickel improve considerably.References[1] S. Dresp et al. ACS Energy Lett.4 (2019) 933–942. [2] N. Ysea et al. Electrocatalysis. 12 (2021) 537–547