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 T_x MXene (Co-B_i /Ti₃ C₂ T_x ) hybrid through fast chemical reactions at room temperature. This interesting hierarchical structure of Co-B_i /Ti₃ C₂ T_x hybrid is beneficial for exposing more active sites, improving mass diffusion, and charge-transfer pathways for electrochemical reaction. Moreover, a strong interaction between Co-B_i and Ti₃ C₂ T_x ensures efficient charge transfer and facilitates the electrostatic attraction of more anionic intermediates for a fast redox process. Consequently, the hierarchical Co-B_i /Ti₃ C₂ T_x 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 .