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Although Ti3C2Tx MXene is a promising material for many applications such as catalysis, energy storage, electromagnetic interference shielding due to its metallic conductivity and high processability, it's poor resistance to oxidation at high temperatures makes its application under harsh environments challenging. Here, we report an air-stable Ti3C2Tx based composite with extracted bentonite (EB) nanosheets. In this case, oxygen molecules are shown to be preferentially adsorbed on EB. The saturated adsorption of oxygen on EB further inhibits more oxygen molecules to be adsorbed on the surface of Ti3C2Tx due to the weakened p-d orbital hybridization between adsorbed O2 and Ti3C2Tx, which is induced by the Ti3C2Tx/EB interface coupling. As a result, the composite is capable of tolerating high annealing temperatures (above 400 °C for several hours) both in air or humid environment, indicating highly improved antioxidation properties in harsh condition. The above finding is shown to be independent on the termination ratio of Ti3C2Tx obtained through different synthesis routes. Utilized as terahertz shielding materials, the composite retains its shielding ability after high-temperature treatment even up to 600 °C, while pristine Ti3C2Tx is completely oxidized with no terahertz shielding ability. Joule heating and thermal cycling performance are also demonstrated. A major challenge for the effective use of Ti-based MXenes in applications with harsh environmental conditions is their poor resistance to oxidation. Here, authors report an air-stable Ti3C2Tx composite with extracted bentonite able to endure high-temperature annealing in air by an oxygen adsorption competition mechanism. [ABSTRACT FROM AUTHOR]

The transport properties of charge carriers in MXene, a promising material, have been studied using terahertz time-domain spectroscopy (THz-TDS) to examine its potential applications in optical and electronic devices. However, previous studies have been limited by narrow frequency ranges, which have hindered the understanding of the intrinsic mechanisms of carrier transport in MXenes. To address this issue, ultrabroadband THz-TDS with frequencies of up to 15 THz to investigate the complex photoconductances of MXene (Ti 3 C 2 T x ) films with different thicknesses are employed. The findings indicate that the electronic localization is substrate-dependent, and this effect decreases with an increase in the number of layers. This is attributed to the screening effect of the high carrier density in Ti 3 C 2 T x . Additionally, the layer-independent photocarrier relaxations revealed by optical pump THz probe spectroscopy (OPTP) provide evidence of the carrier heating-induced screening effect. These results are significant for practical applications in both scientific research and various industries., (© 2023 Wiley‐VCH GmbH.)

With the development of terahertz (THz) technology, there is a booming demand of THz shielding/absorption materials to avoid electromagnetic interference (EMI) or pollution. Paints that can be fast solidified to form a film and stably adherent on arbitrary substrates are especially desired for the shielding/absorption applications. Recently, MXenes with high electron conductivity and hydrophilicity have attracted a great interest for EMI shielding. Here, we demonstrate a copolymer-polyacrylic latex (PAL) based MXene waterborne paint (MWP), which not only has strong THz EMI shielding/absorption efficiency but also can easily adhere onto various substrates that are commonly used in the THz band. The viscosity of MWP can be tuned by adjusting the colloidal and viscous forces, and the cyano group in PAL provides a strong intermolecular polar interaction between MWP and the substrate. As a result, a 38.3-μm-thick MWP on quartz exhibits EMI shielding value of 64.9 dB, and an excellent reflection-loss of 32.8 dB is obtained on MWP coated sponge foam. This substrate-independent MWP provides a simple and efficient way to achieving high-performance THz shielding/absorption.