Nb2O5/Nb2CTx composites with different morphologies through oxidation of Nb2CTx MXene for high-performance microwave absorption

Two-dimensional (2D) transition metal carbides (MXenes) exhibit great potential application in the microwave absorption (MA) field due to their layered structure, excellent dielectric loss and adjustable layer spacing. Herein, Nb2O5 with different morphologies (columnar and irregular granular) was successfully synthesized in situ and implanted between the layers of a Nb2CTx MXene through a rapid microwave-assisted hydrothermal method. Newly formed Nb2O5 and Nb2CTx from an incomplete reaction composed the Nb2O5/Nb2CTx hybrids. Compared with that for the pure Nb2CTx, the Nb2O5/Nb2CTx composites showed enhanced MA performance, especially the Nb2O5/Nb2CTx composites with columnar Nb2O5 (c-Nb2O5/Nb2CTx). The minimum reflection loss (RL) value reached -44.1 dB at 2.8 GHz with a thickness of 5 mm, indicating that approximately 99.99% of the incident microwaves were absorbed. The special morphology of the columnar Nb2O5, the increased lamellar spacing of the Nb2CTx, and the optimized impedance matching characteristic are all important factors that contributed to the enhanced MA performance. (C) 2020 Elsevier B.V. All rights reserved.