Bifunctional electrocatalytic activity of two-dimensional multilayered vanadium carbide (MXene) for ORR and OER

MXenes are a new class of 2D materials that demonstrate effective bifunctional electrocatalytic activity for oxygen reduction (ORR) and evolution reactions (OER). We synthesized V2C (VC–HF) MXene from V2AlC (VAC) via etching using HF at low temperatures. The structure, composition, and morphology of VC-HF MXene were determined using X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) analysis. The XPS analysis demonstrated that VC-HF contained a small amount of Al, suggesting the presence of unreacted VAC even after etching. With an impressive ΔE of ∼0.90 V (the potential difference between ORR and OER), the VC-HF MXene exhibited excellent ORR and OER catalytic activity. This electrocatalyst showed an Eonset of 0.87 V for the reduction of O2, which is remarkable compared to those of the reported bifunctional oxygen catalysts, and exhibited a 430 mV OER overpotential value (η10) at 10 mA cm−2. Besides higher catalytic activity, VC-HF MXene demonstrated good catalytic stability over 10000 s. This work suggests that VC-HF is a promising and efficient bifunctional catalyst for use in various oxygen-based electrochemical devices.