Tuned morphology configuration to augment the electronic structure and durability of iron phosphide for efficient bifunctional electrocatalysis and charge storage

Abstract

Although Fe-based materials have undergone morphological changes to alter their electrochemical activity in energy conversion and storage, an optimal strategy to achieve their ideal performance has yet to be discovered. Herein, a novel planar nanoflower and nanotubes-like morphology were established by the phosphorylation and sulfurization of iron hydroxide to obtain iron phosphide (FeP) and iron sulfide (FeS). Due to the presence of P-coordination with Fe-atoms, FeP material possessed improved electrical conductivity, catalytic property, and significantly specific capacitance among all synthesized samples. The potentiodynamic study was conducted in a 1 M basic solution where 216 and 218 mV of overpotentials were required to drag a current density of 10 mA/cm2 for OER and HER. In addition, the high turnover frequency, electrochemical surface area, and greater roughness factor contribute to making FeP the best candidate for H2 production; hence, it was employed for electrolyzer testing, which showed a lower potential of 1.68 V. Furthermore, FeP demonstrated improved electrochemical storage ability in supercapacitor module forms. The FeP clearly illustrated an outstanding specific capacitance of 2100 mF/cm2 and delivered 98 % stability, which is highly significant as it is not yet achieved by others. This work allows morphological tuning to improve electrocatalysis and charge storage in transition metal-based materials.