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

Highlights: • Porous Cu doped Ni₃S₂ nanosheet arrays were synthesized on Ni foam. • Doping Cu can reduce the contact resistance and accelerate charge transfer. • The optimized Ni_1.9Cu_0.1-S shows a high catalytic activity and stability for OER. 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, Ni_1.9Cu_0.1-S (the chemical composition is Ni_2.85Cu_0.15S₂) displays a small overpotential of 259mV to reach a current density of 10mAcm⁻² and a Tafel slope of 54.9mV dec⁻¹, better than that of undoped Ni₃S₂ (with a overpotential of 274mV). Also, the catalyst possesses pretty OER stability with the overpotential only rising by 1.9% after 12h, which indicate the Ni_1.9Cu_0.1-S nanosheet arrays on Ni foam should be an effective OER catalyst in alkaline medium.