Hydrangea-like bimetallic Ni-Co phosphide electrodeposited on CNT arrays for oxygen evolution reaction

Abstract

The design of efficient and low-cost electrocatalysts for oxygen evolution reaction (OER) is of great significance for the promotion of hydrogen energy utilization. Transition metal phosphides have attracted considerable interest due to their exceptional electrochemical properties. In this study, a hydrangea-like bimetallic nickel–cobalt phosphides were deposited on carbon nanotube arrays using a potentiostatic electrodeposition method. The OER catalytic activity of the composite were optimized by modulating the electrolyte composition and electrodeposition time. The optimal hydrangea-like Ni-Co-P/CNTs@CC-25 catalyst shows an overpotential of 320 mV to deliver the current density of 10 mA cm⁻² and a Tafel slope of 84.04 mV dec⁻¹ in 1 M KOH, which is comparable to RuO₂ standard catalyst. The incorporation of carbon nanotubes (CNTs) enhances the conductivity and stability of the catalyst, while the synergistic effects between Ni and Co phosphides improve its electrochemical activity. Furthermore, the Ni-Co-P/CNTs@CC-25 electrode exhibits remarkable long-term stability, maintaining 76.7 % of its initial current density after 96 h of continuous operation. This work provides an efficient preparation strategy of metal phosphides coupled with CNTs by electrodeposition method.