Cu-doped Ni3S2 nanosheet arrays on Ni foam as an efficient electrocatalyst for oxygen evolution reaction

Abstract Seeking efficient and inexpensive electrocatalysts for the oxygen evolution reaction (OER) is still the key to solving the electrochemical energy conversion process. In this work, Cu doped Ni3S2 nanosheet arrays grown on Ni foam have been synthesized using a two-step hydrothermal method. Doping Cu ion can effectively enhance the conductivity, accelerate charge transfer process and provide more catalytic active sites, thereby improving the OER performance of Ni3S2. In a series of Cu-doped Ni3S2 samples, Ni1.9Cu0.1-S (the chemical composition is Ni2.85Cu0.15S2) displays a small overpotential of 259 mV to reach a current density of 10 mA cm−2 and a Tafel slope of 54.9 mV dec−1, better than that of undoped Ni3S2 (with a overpotential of 274 mV). Also, the catalyst possesses pretty OER stability with the overpotential only rising by 1.9% after 12 h, which indicate the Ni1.9Cu0.1-S nanosheet arrays on Ni foam should be an effective OER catalyst in alkaline medium.