Novel CuO-Cu2O redox induced self-assembly hierarchical NiOOH@CuO-Cu2O/Co(OH)2 nanocomposite for efficient oxygen evolution reaction
Low cost and high-performance electrocatalysts always have been considered for oxygen evolution reaction (OER). Earth-abundant transition-metal-based catalysts are gradually replacing precious metal catalysts due to noble metal lack and high cost. We report a facile method to synthesize an efficient electrode containing NiOOH, CuO-Cu2O components for OER. The nickel foam (NF) was immersed in the mixed alcohol solution containing transition metal nitrate and urea by solvothermal method at 100 ℃. CuO-Cu2O redox induced valence change of nickel and therefore catalyzed the self-assembly of NiOOH@CuO-Cu2O, which formed tightly packed and strongly interacting hierarchical composite contributing to charge transfer. Besides, NiOOH@CuO-Cu2O dispersed on the amorphous Co(OH)2 framework, which were grown in the network sheet of NF. The resulting hierarchical nanocomposite structure greatly increased electron transfer channels. The improved conductivity of the electrode and active sites were conductive to the adsorption and diffusion of OH- from the electrolyte. As the working electrode, the obtained NCC-30 sample had a high catalytic performance of OER with a lower overpotential of 262 mV at a current density of 20 mA cm-2. It also showed long-term catalytic stability that after 48 h i-t testing at 20 mA cm-2 the activity still retained 96 % and sustained the reaction for 15 h at 50 mA cm-2 in 1.0 M KOH. This work suggested that CuO-Cu2O redox induced in-situ self-assembly hierarchical NiOOH@CuO-Cu2O/Co(OH)2 nanocomposites, which grew in the network sheet on NF as a new strategy for preparing efficient OER catalysts.