Porous-Structured Three-Dimensional Iron Phosphides Nanosheets for Enhanced Oxygen Evolution Reaction

Abstract

A rational designing nanostructured Earth-abundant and non-precious electrocatalysts for promoting an anodic oxygen evolution reaction (OER) is crucial for cutting-edge energy conversion and storage fields. Herein, we demonstrate a porous structured three-dimensional (3-D) FeP nanosheets on NiO modified Ni electrode (PS-3D-FeP@NiO|Ni) using of a facile and two-step electrodeposition strategy that exhibits enhanced OER under alkaline electrolyte. The as-developed porous-structured 3-D FeP nanosheets on NiO modified Ni electrode exhibits the best OER catalytic activity in relations of low onset potential (ղonset) of ~1.37 V (vs. RHE), small overpotential (η) of ~0.17 V to produce the current densities of 10 mA cm−2, lower Tafel slope value of ~40.0 mV/dec, higher turn-over frequency (TOF) of 0.435 s−1, and long-term stability when compared to other CoP@NiOǀNi, NiP@NiOǀNi, CuP@NiOǀNi, NiP|NF (nickel foam), and commercial IrO2|Ni electrodes established in this study. The anodic current density is calculated at the potential of ~1.80 V to be ~580, ~365, ~145, ~185, ~516, and 310 mA cm−2 for PS-3D-FeP@NiO|Ni, CoP@NiOǀNi, NiP@NiOǀNi, CuP@NiOǀNi, IrO2|Ni, and FeP|NF electrodes, respectively. The porous structured 3-D FeP nanosheets on NiO modified Ni electrode demonstrated a highest current density of ~580 mA cm−2 at ~1.80 V in comparison to other electrodes employed in the current investigation. The outperforming OER activity of PS-3D-FeP@NiO|Ni is majorly associated to its porous-structured 3-D sheet-like morphology, large amount of electrochemical active surface area, high electrical conductance characteristics and self-activated/supported active sites, facilitating the catalytic properties. The surface morphology, crystalline structure, chemical composition, and distribution of Fe, P and O elements have not been altered significantly after had a long-term OER test. These experimental results reveal that further optimization of porous structured 3D FeP nanomaterials is highly anticipated for practical water electrolysis systems.