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, Nb 2 O 5 with different morphologies (columnar and irregular granular) was successfully synthesized in situ and implanted between the layers of a Nb 2 CT x MXene through a rapid microwave-assisted hydrothermal method. Newly formed Nb 2 O 5 and Nb 2 CT x from an incomplete reaction composed the Nb 2 O 5 /Nb 2 CT x hybrids. Compared with that for the pure Nb 2 CT x , the Nb 2 O 5 /Nb 2 CT x composites showed enhanced MA performance, especially the Nb 2 O 5 /Nb 2 CT x composites with columnar Nb 2 O 5 (c-Nb 2 O 5 /Nb 2 CT x). 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 Nb 2 O 5 , the increased lamellar spacing of the Nb 2 CT x , and the optimized impedance matching characteristic are all important factors that contributed to the enhanced MA performance. • Controllable morphology regulation of Nb 2 O 5 was achieved through oxidation of Nb 2 CT x. • Nb 2 O 5 with a columnar structure could supply expanded spacing between Nb 2 CT x layers. • Impedance matching and multiple scattering were enhanced for Nb 2 O 5 /Nb 2 CT x composites. [ABSTRACT FROM AUTHOR]