MAX Phase (Nb4AlC3) For Electrocatalysis Applications

Abstract In search for novel materials to replace noble metal‐based electrocatalysts in electrochemical energy conversion and storage devices, special attention is given to a distinct class of materials, MAX phase that combines advantages of ceramic and metallic properties. Herein, Nb 4 AlC 3 MAX phase is prepared by a solid‐state mixing reaction and characterized morphologically and structurally by transmission and scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, nitrogen‐sorption, X‐ray diffraction analysis, X‐ray photoelectron and Raman spectroscopy. Electrochemical performance of Nb 4 AlC 3 in terms of capacitance as well as for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is evaluated in different electrolytes. The specific capacitance C s of 66.4, 55.0, and 46.0 F g −1 at 5 mV s −1 is determined for acidic, neutral and alkaline medium, respectively. Continuous cycling reveals high capacitance retention in three electrolyte media; moreover, increase of capacitance is observed in acidic and neutral media. The electrochemical impedance spectroscopy showed a low charge transfer resistance of 64.76 Ω cm 2 that resulted in better performance for HER in acidic medium (Tafel slope of 60 mV dec −1 ). In alkaline media, the charge storage value in the double layer is 360 mF cm −2 (0.7 V versus reversible hydrogen electrode) and the best ORR performance of the Nb 4 AlC 3 is achieved in this medium (Tafel slope of 126 mV dec −1 ).