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

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. The optimized Ni1.9Cu0.1-S electrode showed better catalytic performances for OER in charge transfer, reaction kinetics and catalytic stability. [Display omitted] •Porous Cu doped Ni3S2 nanosheet arrays were synthesized on Ni foam.•Doping Cu can reduce the contact resistance and accelerate charge transfer.•The optimized Ni1.9Cu0.1-S shows a high catalytic activity and stability for OER.