Hydrogen production by water electrolysis using TEA.PS-BF4 ionic liquid and alternative electrocatalysts

Abstract

Studies on water electrolysis are in permanent development to improve its processes with electrodes and electrolytes that offer lower overpotential values. This work uses an ionic liquid (IL) – tetrafluoroborate of 3-triethylammonium-propane sulfonic acid (TEA-PS.BF4) – as electrolyte and studies the effect of different electroactive cathode materials on hydrogen production, such as platinum (Pt), nickel (Ni), palladium (Pd), gold (Au) or silver (Ag). Water electrolysis was performed in a Hoffman Cell and analysed by chronoamperometry (CA) and linear sweep voltammetry (LSV) techniques. For the electrodes studied here, in a 0.1 M TEA-PS.BF4 solution, current density (j) values were 252-404 mA cm-2; for 0.3 M TEA-PS.BF4, values were 406-728 mA cm-2; and for 0.7 M, values were 822-1055 mA cm-2. Low activation energy (Ea) of 5 kJ mol-1 was found for the Au cathode, 9 kJ mol-1 for Pt and Ag, and 24 kJ mol-1 for Ni and Pd. Results show that the Ni electrode is an attractive alternative for hydrogen production by water electrolysis and using IL as electrolyte.