Construction of Co(CO3)0.5OH/Cu Mott-Schottky heterojunctions on Ni foams as an efficient electrocatalyst for oxygen evolution reaction

Abstract

Oxygen evolution reaction (OER) is an important semi-reaction in the electrolysis of water, but it requires a cheap and efficient catalyst to solve the inherent problem of slow kinetics. In this work, we present an efficient strategy to improve electrocatalytic performance by constructing a Mott-Schottky heterojunction via the Cu layer. The Co(CO3)0.5OH/Cu/NFs sample with a Mott-Schottky structure was prepared by depositing Co(CO3)0.5OH nanowire arrays on the surface of NFs plated with a Cu layer. The sample can deliver much better OER performance given the low overpotential of 253 mV at 10 mA cm−2, and extremely low Tafel slope of 48 mV dec−1, even lower than that of commercial OER catalyst RuO2. The significant performance enhancement can be attributed to the Mott-Schottky structure of Co(CO3)0.5OH/Cu. In particular, the intrinsic activity of the sample is improved by the Mott-Schottky structure of Co(CO3)0.5OH/Cu, in which the spontaneous electron will transfer from Cu to Co(CO3)0.5OH, hence reducing the OER overpotential. Then, the conductivity of the sample is initially enhanced by the Cu layer, thus improving the charge transport speed in the process of OER. Furthermore, in the constructed sandwich structure, the dense Co(CO3)0.5OH and NF substrates can avoid the corrosion of Cu by the electrolyte, maintaining good stability beyond 50 h. This strategy is also applicable to other OER materials, such as NiFe LDH, CuNi LDH, and CoP, and their performances can be significantly improved. This work provides a universal method of constructing efficient Mott-Schottky electrocatalysts for OER, consequently providing a wide range of application prospects.