In situ transformation of sea urchin-like NixCoyP@NF as an efficient bifunctional electrocatalyst for overall water splitting

• Published in: Journal of materials science. Materials in electronics Vol. 32; no. 2; pp. 1951 - 1961
• Main Authors: Kong, Teng, Sui, Yanwei, Qi, Jiqiu, Wei, Fuxiang, Ren, Yaojian, Zhan, Zhenzhen, Sun, Zhi, Zhou, Meihua, Meng, Dongmei, Zhang, Lijun, Ma, Lan, Wang, Qun
• Format: Journal Article
• Language: English
• Published: New York Springer US 2021; Springer Nature B.V
• Subjects: Bimetals; Characterization and Evaluation of Materials; Chemistry and Materials Science; Current density; Electrocatalysts; Electrochemical analysis; Hydrogen evolution reactions; Hydrothermal reactions; Materials Science; Morphology; Nickel; Noble metals; Optical and Electronic Materials; Oxygen evolution reactions; Phosphides; Phosphorylation; Specific surface; Substrates; Surface area; Transition metals; Water splitting
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-04963-7

Transition metal phosphides (TMPs) are a hopeful noble-metal-free catalysts for water splitting. In this study, we used a three-dimensional nanostructure on nickel substrate to easily synthesize a nickel–cobalt phosphide electrocatalyst (Ni
x
Co
y
P,
x
 = 1, 1.5, 2;
y
 = 1, 1.5, 2) through hydrothermal reaction and in situ phosphorylation. The NiCo
1.5
P exhibited relatively excellent oxygen evolution activity performance, and it only needed the overpotentials of 123 mV for HER in 1 M KOH to perform the current densities of 10 mA cm
−2
. It is worth mentioning that the Ni
2
CoP exhibited better bifunctional electrocatalyst characteristics. As to water splitting, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) require 197 and 253 mV overpotentials separately to provide a current density of 10 mA cm
−2
. Its relatively excellent electrochemical performance can be ascribed to the high-density sea urchin-like three-dimensional structure, which provides greater specific surface area and more active site. Besides, Ni
2
CoP also shows long-term durability lasting 80,000 s, and on this basis, there is no distinct deactivation. This work emphasizes that Ni
2
P and CoP play a vital role relative to the good activity of HER. Moreover, the unique morphology with self-supported structure provides a larger specific surface area, making it possible the exposure of higher amount of active sites for HER. These self-supported electrocatalysts that do not require a binder could also make the electrode more active and stable. This work, therefore, presents a strategy that is controllable and feasible strategy for the synthesis of bimetallic phosphides with unique morphology and high HER and OER activity.