Materials with good flexibility and high conductivity that can provide electromagnetic interference (EMI) shielding with minimal thickness are highly desirable, especially if they can be easily processed into films. Two-dimensional metal carbides and nitrides, known as MXenes, combine metallic conductivity and hydrophilic surfaces. Here, we demonstrate the potential of several MXenes and their polymer composites for EMI shielding. A 45-micrometer-thick Ti3C2Tx film exhibited EMI shielding effectiveness of 92 decibels (>50 decibels for a 2.5-micrometer film), which is the highest among synthetic materials of comparable thickness produced to date. This performance originates from the excellent electrical conductivity of Ti3C2Tx films (4600 Siemens per centimeter) and multiple internal reflections from Ti3C2Tx flakes in free-standing films. The mechanical flexibility and easy coating capability offered by MXenes and their composites enable them to shield surfaces of any shape while providing high EMI shielding efficiency.

Due to their unique properties and diversity, two-dimensional (2D) nanomaterials have attracted tremendous interest from the scientific community in recent years, especially for energy storage applications. Herein, we present a strategy to prepare flexible and conductive MXene/graphene (reduced graphene oxide, rGO) supercapacitor electrodes by using electrostatic self-assembly between positively charged rGO with poly(diallyldimethylammonium chloride) and negatively charged MXene nanosheets. After electrostatic assembly, rGO nanosheets are inserted in-between MXene layers. As a result, the self-restacking of MXene nanosheets is effectively prevented, leading to a considerably increased interlayer spacing. Accelerated diffusion of electrolyte ions enables more electroactive sites to become accessible. The as-prepared freestanding MXene/rGO-5wt% electrode displays a volumetric capacitance of 1040 F cm -3 at a scan rate of 2 mV s -1 and anThis article is protected by copyright. All rights reserved.3 impressive rate capability with 61% capacitance retention at 1 V s -1 . Moreover, the film electrode exhibits long cycle life with almost no capacitance decay after 20,000 cycles. More importantly, our binder-free, symmetric supercapacitor fabricated with MXene/rGO-5wt%shows a maximum volumetric energy density of 34.6 Wh L -1 and an ultrahigh volumetric power density up to 74.4 kW L -1 , which is among the highest values reported for carbon and MXene based materials in aqueous electrolytes. This work not only provides fundamental insight into the effect of interlayer spacing on the electrochemical performance of 2D hybrid materials, but also sheds light on the design of next-generation flexible, portable and highly integrated supercapacitors with high volumetric and rate performances.

Influences from solvents on charge storage in titanium carbide MXenes. (2019) Nature Energy, 4 (3). 241-248.

MXene/carbon composite electrodes with high loadings of MXene were prepared via electrospinning. These flexible and free-standing electrodes exhibit high areal capacitance relative to pure carbon nanofibers and MXene-coated fibers and textiles.

Until now, MXenes could only be produced from MAX phases containing aluminum, such as Ti AlC . Here, we report on the synthesis of Ti C (MXene) through selective etching of silicon from titanium silicon carbide-the most common MAX phase. Liters of colloidal solutions of delaminated Ti SiC -derived MXene (0.5-1.3 mg mL ) were produced and processed into flexible and electrically conductive films, which show higher oxidation resistance than MXene synthesized from Ti AlC . This new synthesis method greatly widens the range of precursors for MXene synthesis.