Design,Fabrication,and Application Of MXene-Based Dynamically Controllable Intelligent Electromagnetic Shielding Devices

With the rapid development of electronic information technology,traditional electromagnetic interference shielding materials with fixed shielding performance are unable to cope with the increasingly complex electromagnetic environments.Therefore,dynamically tunable electromagnetic interference shielding devices with adjustable performance have gained significant application value in military and civilian fields.However,current researches on dynamically tunable intelligent electromagnetic interference shielding devices suffers from drawbacks such as narrow effective bandwidth,complex processes,and difficulties in large-scale applications.Two-dimensional layered transition metal carbide/nitride（MXenes）materials have attracted extensive attention in the field of electromagnetic interference shielding due to their excellent conductivity,hydrophilicity,and chemical activity.Leveraging the zero or narrow bandgap energy band structure,tunable surface resistance,and the capability for large-scale manufacturing of two-dimensional Ti₃C₂ nanosheets,a novel Ti₃C₂ sandwich structure was designed and fabricated for dynamic tunable intelligent electromagnetic shielding devices,and its structure,performance,and applications were systematically investigated.The main contributions of this paper include:1.Ti₃C₂ nanosheets were successfully synthesized using in-situ generated HF etching method,and nanosheets with different sizes were prepared by controlling the ultrasonic oscillation time.The working electrodes for the Ti₃C₂ sandwich structure were prepared using the spray coating method.The resulting Ti₃C₂ film electrodes exhibited excellent electromagnetic interference shielding performance across the entire X-band,and the electromagnetic interference shielding effectiveness could be adjusted by varying the spray coating time.2.The variations of the electromagnetic properties of the Ti₃C₂ sandwich structure under applied bias were investigated.At a low voltage of-1.5 V,the resistance of the Ti₃C₂ film working electrode decreased by 63%,demonstrating excellent resistance modulation capability.Based on the tunable surface resistance of the Ti₃C₂ film in the sandwich structure,the effects of Pt electrode structure and electrode spacing on the electromagnetic interference shielding modulation performance of the device were studied from the aspects of capacitance,resistance,and electromagnetic interference shielding effectiveness.A novel ultra-thin Pt/Ti₃C₂ sandwich structure based on a planar grid-like Pt electrode was designed and fabricated for dynamically tunable smart electromagnetic interference shielding devices.3.Optimization of the Ti₃C₂ working electrode in the novel Pt/Ti₃C₂ sandwich structure was performed to improve the performance of electromagnetic interference shielding modulation.Firstly,by varying the spray coating time,Ti₃C₂ working electrodes with different sheet resistances were prepared,enabling the device to switch between different electromagnetic interference shielding modulation ranges.Secondly,devices fabricated using Ti₃C₂ nanosheets with different sizes exhibited different electromagnetic interference shielding modulation capabilities within different sheet resistance ranges.Finally,two application scenarios were proposed based on the above work:an electromagnetic interference shielding"switch"surface for electromagnetic interference shielding state switching and a microwave dynamic camouflage surface based on MXene for microwave dynamic camouflage.By controlling the voltage applied to the electromagnetic interference shielding"switch"surface,the device could switch between"transparent"and"shielding"states.The electromagnetic interference shielding"switch"surface achieved switching of electromagnetic interference shielding effectiveness between 17.5 d B and 24.2 d B at low voltages of 0.1 V to-1.5 V,with an average modulation amplitude of 6.7 d B in the X-band.It achieved the effect of switching between the"ON"and"OFF"states of electromagnetic interference shielding.Furthermore,by combining the structure of the Salisbury screen,a microwave dynamic camouflage surface based on MXene was designed and fabricated.This dynamic camouflage surface achieved modulation of reflection amplitude ranging from-12.0 d B to-44.0 d B under a bias voltage of 0.1 V to-1.0 V,with a reflection modulation magnitude of 32 d B at 10.5 GHz.The effective absorption bandwidth（<-10d B）in the X-band accounted for more than 70%,demonstrating broadband dynamic camouflage capability.The camouflage ability of the MXene-based dynamic camouflage surface shows the best effect among similar devices reported so far.This research offers a more promising solution for the application of dynamic tunable smart electromagnetic interference shielding devices,with its simplified fabrication process and potential for low-cost large-scale manufacturing.