Sandwich-like CoP/C nanocomposites as efficient and stable oxygen evolution catalysts

Abstract

Nowadays, the sluggish kinetics of the oxygen evolution reaction (OER) has been a bottleneck factor in water electrolysis. Designing and synthesizing some materials, with novel and specific morphology, may hopefully relieve the present puzzle. Herein, a novel sandwich-like CoP/C nanocomposite was developed by a low-temperature phosphorization method using a carbon-encapsulated Co-based nanosheet as a precursor. The cross-section images directly show that the monodispersed CoP nanoparticles are sandwiched between two thin carbon layers. The outer coating of CoP nanoparticles serves as an efficient protective layer and conductive medium in the process of water electrolysis. Remarkably, the sandwich-like CoP/C obtains a small overpotential of only 330 mV (1.56 V vs. RHE) at a current density of 10 mA cm⁻², which is favorably compared with the commercial IrO₂/C (400 mV), sandwich-like CoO/C (450 mV) and macroporous CoP (610 mV) catalysts we prepared. This CoP/C nanocomposite also presents better stability in alkaline solution than that of CoO/C and macroporous CoP. What is important is that this excellent OER performance has exceeded most Co-based materials reported thus far. The sandwich-like CoP/C material we obtained affords the possibility of the pursuit of robust, low-cost and high-effective OER catalysts.