Integrating a metal framework with Co-confined carbon nanotubes as trifunctional electrocatalysts to boost electron and mass transfer approaching practical applications.

A facile and large-scale construction of robust and inexpensive trifunctional self-supporting electrodes for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in metal-air batteries and water splitting is crucial but remains challenging. Herein, we report a direct and up-scalable all-solid-phase strategy for the synthesis of a porous three-dimensional electrode consisting of cobalt nanoparticles wrapped in nitrogen-doped carbon tubes (Co/N-CNTs), which are in situ planted onto the surface of a cobalt foam. The resultant Co/N-CNTs can directly serve as a self-supporting and adhesive-free electrode with excellent and durable catalytic performances for the ORR, OER and HER. The metal framework substrate with an open-pore architecture is favorable for electron and mass transfer and allows fast catalytic kinetics. More importantly, when used in Zn-air batteries and overall water splitting, the as-prepared Co/N-CNT electrode displays a remarkable performance, implying bright perspects for practical application.