Gas-specific adsorption capability of titanium dioxide and MXene nanocomposite thin films prepared by ultrasonic spray printing using inks oxidized at room temperature.

The development of two-dimensional (2D) layered MXene materials has opened new possibilities for gas adsorption applications due to their high specific surface area, tunable surface chemistry, and excellent selectivity towards specific gases. These materials exhibit tremendous potential in adsorption-based gas separation and detection, particularly due to their strong interactions with target gas molecules, making them highly effective in gas removal and detection applications. However, currently available methods for synthesizing these oxidized nanocomposite inks are limited by the typically high temperatures involved. The present work addresses this issue by developing titanium dioxide and MXene (TiO/TiC MXene) nanocomposite inks, where TiO nanoparticles are formed between the layers of the TiC MXene via oxidation in solution state under extended exposure in an oxygen rich atmosphere at room temperature. As a proof of concept, gas adsorption studies are conducted by applying the TiO/TiC MXene nanocomposite inks onto gold-coated silicon wafers via an ultrasonic spray printing method. The gas adsorption results demonstrate that the TiO/TiC MXene nanocomposites possess excellent adsorption selectivity toward methane and butane among alkane gases, and can achieve maximum adsorption capacities of 8.62 and 18.8 cm/g, respectively. The results of ultrasonic spray printing quality tests conducted for different numbers of printed layers using the proposed TiO/TiC MXene nanocomposite ink demonstrate that the film thickness can be regulated by controlling the number of printed layers, and the average thin film thickness remains only 0.313 μm for 10 printed layers. Meanwhile, the average roughness of the films resides between 0.130 μm (3 layers) and 0.220 μm (8 layers), which is uniformly and less than the average roughness of 0.225 μm measured for the original gold-plated silicon wafer. Hence, by employing facile ink-based printing techniques, such as ultrasonic spray printing, thin films with controlled thickness can be fabricated, thereby laying the foundation for their practical applications in environmental monitoring and industrial gas separation.