Pulsed laser ablation synthesis of Cu-based and Ni-based nanostructured electrodes for highly active alkaline oxygen and hydrogen evolution reactions

Abstract

In the field of sustainability, hydrogen (H2) is considered a clean fuel and a renewable energy source with no pollutant emissions. The production of H2 by water electrolysis is well-known among the scientific community. Still, alkaline electrolysis represents a challenging process and requires expensive materials have to be avoided in order to lower the impact of H2 production. This work deals with the production of copper (Cu) and nickel (Ni) nanoparticles (NPs) as catalysts for alkaline water splitting reactions. These NPs are synthesized using the pulsed laser ablation in liquid involving the ablation of Cu and Ni targets in methanol and ethanol. The morphological, structural, and compositional properties of the obtained NPs are studied. Then, a low amount of NPs-based catalyst (∼1μg/cm2) was loaded onto a nickel foam substrate and tested for both alkaline Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER). The best performance at 10 mA cm−2, in terms of overpotential (η), for OER was shown by Ni NPs, η = 327 mV, while for the HER, Cu NPs reached η = 211 mV at 10 mA cm−2 in aqueous 1M KOH. The ultra-low amount of the catalyst material makes these electrodes challenging in terms of mass activity [up to 14 A/mg at 10 mA cm−2] compared to the state of the art. In addition, the correlation between overpotential and the availability of electrons at the surface of the catalyst for H2 production was studied by using Mott–Schottky analysis.