Nickel selenide as a high-efficiency catalyst for oxygen evolution reaction

• Published in: Energy & environmental science 2016-05, Vol.9 (5), p.1771-1782
• Main Authors: Swesi, A. T, Masud, J, Nath, M
• Format: Article
• Language: English
• Subjects: Catalysts; Catalytic activity; Current density; Deposition; Evolution; Nickel; Oxygen; X-rays
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c5ee02463c

A metal-rich form of Ni-selenide, nickel subselenide, Ni 3 Se 2 has been investigated as a potential oxygen evolution electrocatalyst under alkaline conditions for the first time. The Ni 3 Se 2 phase has a structure similar to the sulfur mineral heazlewoodite, which contains metal-metal bonding. The electrocatalytic activities of Ni 3 Se 2 towards OER were seen to be at par with or even superior to the transition metal oxide based electrocatalyst in terms of onset overpotential for O 2 evolution as well as overpotential to reach a current density of 10 mA cm −2 (observed at 290 mV). The electrocatalytic Ni 3 Se 2 films were grown by electrodeposition on conducting substrates and the deposition parameters including the pH of the electrolytic bath, deposition potential, and substrate composition were seen to have some influence on the catalytic activity. So far, Ni 3 Se 2 films deposited on the Au-coated Si substrate was seen to have the lowest overpotential. Annealing of the as-deposited electrocatalytic films in an inert atmosphere, enhanced their catalytic efficiencies by decreasing the overpotential (@10 mA cm −2 ) as well as increasing the current density. The structure and morphology of these films has been characterized by powder X-ray diffraction, scanning and transmission electron microscopy, Raman, and X-ray photoelectron spectroscopy. Catalytic activities were investigated through detailed electrochemical studies under alkaline conditions, including linear sweep voltammetry, chronoamperometric studies at constant potential, electrochemical surface area determination and calculation of the Tafel slope. The Faradaic efficiency of this catalyst has been estimated by reducing the evolved O 2 in a RRDE set-up which also confirmed that the evolved gas was indeed O 2 . In addition to low overpotentials, these Ni 3 Se 2 electrodeposited films were seen to be exceptionally stable under conditions of continuous O 2 evolution for an extended period (42 h). Ni 3 Se 2 has been identified as a high-efficiency oxygen evolution catalyst with low onset potential and extended stability under alkaline conditions.