Facile electrochemical synthesis of Ni-Co-B film on Cu sheet for dual-electrocatalysis of hydrogen and oxygen evolution reactions

Abstract

Fabricating efficient and affordable electrocatalysts is essential to make electrochemical water splitting more feasible. However, to minimize the electrocatalysts' fabrication costs, developing bifunctional electrocatalysts has been proposed as a profitable strategy. Herein, the Ni-Co-B film was fabricated on a Cu sheet surface by a one-step and facile electrodeposition method. The optimized sample showed noticeable electrocatalytic activity for total water splitting. The required overpotential for hydrogen evolution reaction (HER) at -10 mA cm−2 current density was recorded to be -145 mV, and in the case of oxygen evolution reaction (OER), this value was 276 mV at 10 mA cm−2. The unique morphology of the optimized Ni-Co-B sample with a high number of spherical micro-nodules was proposed to be responsible for this high HER and OER catalytic activity. Moreover, the optimized value of the B, Ni, and Co in the coating was highly important in facilitating the electrochemical reactions. Density functional theory (DFT) calculations indicated that the better electrocatalytic activity of the Ni-Co-B electrode is due to the regulate the electronic structure and new active catalytic sites which are created by Co incorporation. Finally, the binder-free approach of fabricating the coating resulted in the long-time high stability of the fabricated Ni-Co-B/Cu electrode at high current densities.