Carbon Nanotube Encapsulated Metal Selenide Eelectrocatalyst for Oxygen Evolution Reaction

Abstract

The oxygen evaluation represents an important reaction in electrochemical water splitting and metal-air batteries. To deal with the increasing energy crisis, production of low-cost, high-efficiency, and robust oxygen evolution reaction (OER) electrocatalysts is urgently needed. Recently, transition metal chalcogenides (TMCs) have been used as active electrocatalysts for OER because of their high electric conductivity and enriched redox chemistry. These chalcogenide based electrocatalysts show unprecedented high activity surpassing state-of-the-art precious metal oxides or hydroxide-based catalysts. In the present work, nickel selenide nanorods (NRs) were grown inside carbon nanotubes (NiSe@CNT) through chemical vapor deposition (CVD) wherein, the carbon nanostructure formed in-situ wrapping around the growing nickel selenide nanorods. Electrocatalytic behavior was explored by various electrochemical studies, including linear sweep voltammetry (LSV), chronoamperometric experiments, electrochemical surface area determination, and Tafel slope calculation, under highly alkaline condition. It was observed that this NiSe@CNT composites showed enhanced electrocatalytic activity for OER. Our results indicate that the self-grown CNT around Nickel selenide increases catalytic activity of this hybrid due to an increased number of catalytic sites and electronic conductivity of the nanocomposite. The overpotential at 10 mA cm-2 current density for the as-synthesized NiSe@CNT catalyst is 270 mV which is much better than precious metal based electrocatalysts for OER, such as RuO2 and IrO2. In addition, before and after the 40 h chronoamperometry stability test, the LSV curves were almost similar confirming that the as-synthesized catalyst could give stable electrocatalytic OER activity in 1 M KOH medium for the extended time period. The as-synthesized catalyst was characterized by XRD, Raman spectroscopy, XPS and TEM for morphology, elemental and chemical compositions.