Halloysite nanotubes decorated with Co(OH)F nanorods as a novel binary composite for the enhanced electrocatalytic water oxidation

Oxygen evolution reaction is central to several emerging electrochemical energy conversion and storage technologies. This study reports the synthesis, characterization, and OER electrocatalytic performance of binary nanocomposites composed of halloysite nanotubes (HNTs) and Co(OH)F. Five Co(OH)F/HNT with different compositions were fabricated by a facile hydrothermal synthesis. The crystalline phase and microstructure of the as-prepared materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesized Co(OH)F (pristine or mixed with HNTs in the nanocomposites) revealed an orthorhombic crystal system with a nanorod morphology. The nanocomposite with similar to 19 wt% of Co (designated as Co(OH)F/HNT_3) was found to possess an appreciably improved activity in OER compared to the pristine HNTs, Co(OH)F, and other Co(OH)F/HNT nanocomposites. Co(OH)F/HNT_3 displayed an overpotential of 252 mV (at the current density of 10 mA cm(-2)), a Tafel slope of 51.1 mV dec(-1), and a robust operational performance under harsh alkaline conditions. Furthermore, nitrogen adsorption-desorption isotherms indicated a much higher specific surface area for this nanocomposite than its components. Overall, the versatile synthesis and outstanding catalytic performance of Co(OH)F/HNT_3 make it an auspicious earth-abundant transition metal-based electrocatalyst for OER in an alkaline medium.