It is challenging but desirable to develop active and stable electrocatalysts for water splitting to produce H2 fuel and O2 through hydrogen evolution (HER) and oxygen evolution (OER) reactions, respectively for feeding to the fuel cell. OER and HER are considered to be clean and sustainable energy technology and an alternative for fossil fuels. However, large scale elctrochemical water splitting is a kinetically sluggish mainly because of the slow OER process which necessitates 4 electron conversion and O=O bond formation. Typically, catalysts are used to address this great challenge and make the process more efficient. Herein we report, identification of a highly active Ni3Se2 electrocatalyst for oxygen evolution in alkaline condition. The Ni3Se2 phase has a structure similar to the sulfur mineral Heazlewoodite, which contains metal – metal bonding. The electrocatalytic activities of Ni3Se2 towards OER was seen to be at par with or even superior to the transition metal oxide based electrocatalyst in terms of onset overpotential for O2 evolution as well as overpotential to reach a current density of 10 mA/cm2 (observed at 220 mV). This system is also efficient for catalyzing the hydrogen evolution reaction in the same media. The bifunctional catalyst enables water electrolyzer without degradation in a two-electrode configuration and 0.3M KOH. The electrocatalytic Ni3Se2 were grown by electrodeposition on conducting substrates and the deposition parameters including pH of the electrolytic bath, deposition potential, and substrate composition, as well as choice of Ni- and Se-precursors were seen to have some influence on the catalytic activity. In addition to low overpotentials, these Ni3Se2 electrodeposited films were seen to be exceptionally stable under conditions of continuous O2 evolution for period (~3 days). The structure and morphology of these films has been characterized with powder X-ray diffraction, Scanning and Transmission electron microscopy, Raman, and X-ray photoelectron spectroscopy. We will discuss in detail the electrochemical and structural characterizations of these films along with catalytic activities.

Electrocatalytic overall water splitting on nickel selenide (Ni3Se2)

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.