Cu_xO nanorod arrays shelled with CoNi layered double hydroxide nanosheets for enhanced oxygen evolution reaction...

Exploration of highly efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts is of crucial importance for the development of water splitting. In recent years, Cu-based materials have been widely concerned in OER due to their non-toxicity, rich reserves and highest reversibility. Meanwhile, Cu_xO nanorods is easy to be prepared in industry. Herein, we report a fast preparation method to construct an integrated Cu_xO@CoNi-LDH electrocatalyst with a unique 1D nanowire-2D nanosheet hierarchical core-shell structure by electrodepositing CoNi-LDH nanosheet arrays directly onto Cu_xO nanorods (Cu_xO were in situ-created on the Cu foam) at a large deposition voltage of -3.0 V vs SCE. The unique heterogeneous core-shell nanostructure, large deposition amount of CoNi-LDH and the synergistic effects between Cu_xO core and CoNi-LDH shell can provide abundant active sites, rich open-channels and reduced charge transfer resistance (R_ct) for effective oxygen release and facile electron transport. Consequently, the optimized Cu_xO@CoNi-LDH/CF exhibits a low overpotential of 207 mV in 1 M KOH solution at the current density of 10 mV cm^-2 and a small Tafel slope of 50.1 mV dec^-1. After 60 h of long-term stability test, the catalytic performance is only slightly weakened. This work demonstrates a new approach to design the high-performance LDH and Cu-related OER catalysts by constructing a unique hierarchical core-shell nanostructure.