Construction of hierarchical nickel/cobalt iron-hydroxide and nickel/cobalt selenide nanotubes for efficient electrocatalytic water splitting

Abstract

The exploration and fabrication of highly effective and low cost non-precious electrocatalysts are very essential for the hydrogen production industry. Herein, for the first time we constructed and prepared Ni/CoFe hydroxide and Ni/CoSe₂ electrodes with hollow nanotube array structures on conductive nickel foam by a facile two-step electrodeposition method combined with a ZnO self-template strategy. The as-prepared Ni/CoFe hydroxide and Ni/CoSe₂ nanotube arrays only need a relatively low overpotential of 230 mV for OER and 89 mV for HER to achieve a current density of 20 mA cm⁻² and 10 mA cm⁻², respectively. Specifically, an asymmetric alkaline electrolyzer has been assembled by using Ni/CoFe hydroxide as anode and Ni/CoSe₂ as cathode, which requires a low overall potential of only 1.57 V at the current density of 10 mA cm⁻² and displays excellent stability for 20 h. The excellent electrocatalytic performance of the electrodes benefits from the synergistic effect of the different components and the hierarchical hollow nanotube structure with abundant active sites, fast electronic transport and sufficient diffusion channels for electrolyte and gas. The work provides a feasible way to develop highly efficient, hierarchical, hollow-structured and low-cost earth-abundant catalysts for electrocatalytic water splitting applications.