Bimetallic NiMo oxides coupled with 3D CuxO nanorods for efficient overall water splitting

Development of efficient non-precious metal catalysts for water electrolysis is imperative in the area of energy conversion. Herein, transition-metal oxide catalyst of CuxO@NiO-MoO2 nanorods with three-dimensional core–shell nanostructures was constructed by a facile route. The CuxO@NiO-MoO2 NRs supplies a high electrochemical active area, thus exposing more active centers in full contact with the electrolyte. The fast charge transfer between the nanorods and nanoparticles and the synergistic effect among the bimetals enable the catalyst to show superior catalytic performance. CuxO@NiO-MoO2 NRs requires the overpotentials of 65 mV for hydrogen evolution reaction (HER) at 10 mA cm−2 and 321 mV for oxygen evolution reaction (OER) at 50 mA cm−2. Meanwhile, the catalyst also shows satisfactory performance at the high current densities of 100 and 200 mA cm−2 for HER, requiring overpotentials of only 152 and 192 mV, respectively. Moreover, the CuxO@NiO-MoO2 NRs needs a voltage of 1.54 V to achieve 10 mA cm−2 as a water electrolyzer. This study provides a promising route for preparing bifunctional catalysts via the rational design of interfaces and nanostructure arrays.