Impact of the alkalinity on the stability and catalytic activity of Ni/Nb2O5 composite electrodes for the hydrogen evolution reaction in NaCl solutions

YSEA, NADIA; LACCONI, GABRIELA I.; DIAZ, LILIANA A.; FRANCESCHINI, ESTEBAN A.

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2023 vol. 470

0013-4686

This study investigates the stability and catalytic activity of a Ni/Nb2O5 composite catalyst containing 13 wt.% Nb2O5 in 3.43 wt.% NaCl electrolytes with different concentrations of KOH (5.6, 15, and 30 wt.%). Results show that the addition of KOH significantly enhances the catalyst´s stability, compared to NaCl alone. Furthermore, increasing KOH concentration decreases catalytic activity for HER, indicating that the electrolyte´s alkalinization is a trade-off between stability and activity. The decline in catalytic activity is suggested to be due to a change in the reaction mechanism, from generating Cl2 to O2 as KOH concentration increases, favoring water decomposition over oxidation. Raman microscopy and UV–vis absorbance analysis show a decrease in surface oxidation with increasing KOH concentration. Using 3.43 wt.% NaCl with the addition of 5.6 or 15 wt.% KOH is feasible to increase electrode activity while maintaining electrocatalytic activity after aging in full hydrogen evolution, making it a good alternative electrolyte to replace KOH solutions. The findings have important implications for optimizing the synthesis of catalytic materials for H2 production and selecting electrolytes for long-term electrochemical cell operation.