One-step fabrication of a self-supported Co@CoTe2 electrocatalyst for efficient and durable oxygen evolution reactions

Abstract

We report a very convenient and cost-effective approach for the fabrication of a self-supported Co@CoTe₂ electrode comprising CoTe₂ nanoparticles used for water oxidation catalysis, which is achieved by one-step hydrothermal treatment of commercially available cobalt foam. The characteristics of the as-fabricated Co@CoTe₂ electrode in terms of the crystal structure, surface morphology and chemical components were analyzed. Moreover, the electrochemical properties of the Co@CoTe₂ electrocatalyst used for water electrolysis were comprehensively investigated. When used to catalyze the oxygen evolution reaction (OER) in 1.0 M KOH, Co@CoTe₂ electrodes exhibit outstanding catalytic activity and long-term durability, thus outperforming many well-studied cobalt based dichalcogenides (including tellurides, selenides and sulfides) that have been recently reported in the literature. Particularly, Co@CoTe₂ prepared at 240 °C (Co@CoTe₂-240) requires a low overpotential of only 286 mV to attain an anodic current density of 10 mA cm⁻² and shows fast kinetics for the OER with a small Tafel slope of 42 mV dec⁻¹. Moreover, the overpotential needed to maintain 10 mA cm⁻² is merely increased by 20 mV after continuous OER electrolysis for 16 hours, exhibiting excellent long-term stability. Given the commercial availability of porous Co foam, the convenient and scalable approach of hydrothermal synthesis and the outstanding catalytic performance, the self-supported Co@CoTe₂ electrode reported here holds great promise as an important OER electrocatalyst in water splitting devices and metal–air batteries.