Nb-MXene as promising material for electrocatalysis in energy conversion (OER/ORR) and storage

Low-cost non-noble metal electrocatalysts are currently the focus of research and development for energy conversion and storage devices. MXenes, the newest class of two-dimensional materials, have high surface area, nanometer layer thickness, hydrophilicity and high electrical conductivity that favor their performance for electrocatalytic reactions. Herein, niobium carbide MXene (Nb-MXene) was obtained from its MAX phase by chemical synthesis and characterized regarding its morphology, structure and electrochemical activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) as well as for charge storage in different electrolytic media. The results demonstrate the good performance of Nb-MXene for storing charge (104 F g at 5 mV s) that increased remarkably with continuous cycling in an acidic medium. Current density for oxygen evolution of ∼32.5 mA cm was reached in alkaline medium. The oxygen reduction reaction in the same media was observed to proceed via 2e mechanism with a Tafel slope of 114 mV dec. Therefore, Nb-MXene presents characteristics and performance of a promising material for electrocatalytic reactions.