Bifunctional and binder-free S-doped Ni-P nanospheres electrocatalyst fabricated by pulse electrochemical deposition method for overall water splitting

Abstract

Due to their excellent electrocatalytic properties, transition metal phosphides have been considered as desirable and cost-effective electrocatalysts in recent years. However, in many cases, the synthesis of phosphide-based nanostructures requires expensive conditions and toxic phosphorous-containing compounds. Therefore, the emergence of an economical and eco-friendly method for creating phosphides-based nanostructures can be very effective. Here, S-doped Ni-P nanospheres were created using a novel pulse electrochemical deposition method, and its hydrogen evolution reaction (HER), as well as oxygen evolution reaction (OER) electrocatalytic activity and stability were investigated. Inspired by the high electrochemically active surface area, the synergistic effect between S and P, the rapid detachment of the gasses from the surface and thus the lowered resistance resulted from bubbles pinning, and ultimately the increased wettability due to nanostructuring, the electrode exhibited outstanding electrocatalytic activity for HER and OER processes. The electrode requires only 55 mV and 229 mV overproduction to be able to afford the current density of 10 mA.cm−2 for HER and OER processes, respectively. Furthermore, at a current density of 100 mA.cm−2, these electrodes showed minor changes in potential, indicating the superb electrocatalytic stability of the synthesized electrode. Moreover, in the overall water splitting process, the S-doped Ni-P electrode requires only 1.51 V to generate a current of 10 mA.cm−2. The results of this study indicate the successful use of pulse electrochemical deposition method to create active electrocatalysts.