Hierarchical Cobalt Borate/MXenes Hybrid with Extraordinary Electrocatalytic Performance in Oxygen Evolution Reaction.

Oxygen evolution reaction (OER) is a key reaction for many renewable energy storage and conversion techniques. Developing efficient non-precious metal-based electrocatalysts for OER has attracted increasing attention. Herein is reported a strategy to fabricate hierarchical cobalt borate/Ti3 C2 Tx MXene (Co-Bi /Ti3 C2 Tx ) hybrid through fast chemical reactions at room temperature. This interesting hierarchical structure of Co-Bi /Ti3 C2 Tx hybrid is beneficial for exposing more active sites, improving mass diffusion, and charge-transfer pathways for electrochemical reaction. Moreover, a strong interaction between Co-Bi and Ti3 C2 Tx ensures efficient charge transfer and facilitates the electrostatic attraction of more anionic intermediates for a fast redox process. Consequently, the hierarchical Co-Bi /Ti3 C2 Tx hybrid shows extraordinary OER catalytic activity to deliver a current density of 10 mA cm-2 at an overpotential of 250 mV, and a Tafel slope of about 53 mV dec-1 .