In situ construction of a Zn2SnO4/TiO2/Ti3C2Tx heterostructured composite allows for rapid sensing of n-hexanol under ultraviolet light illumination

Abstract

Due to the oxygen vacancy concentration in metal oxides playing a crucial role in gas sensing performance, this study focuses on the strategy of oxygen vacancy modulation in Zn₂SnO₄ to achieve rapid detection of n-hexanol gas. It presents the synthesis of a nano-heterostructured composite material, where TiO₂ and an MXene are in situ integrated into Zn₂SnO₄ nanoparticles via a calcination process. The incorporation of TiO₂ and the MXene significantly increases the oxygen vacancy concentration and the specific surface area of the composite, which thus exerts a positive impact on its gas sensing performance toward n-hexanol. Owing to the presence of TiO₂, the heterostructured composite possesses photocatalytic properties, which further enhances the sensing performance of n-hexanol and notably reduces the working temperature under UV illumination. Through optimizing the MXene content and utilizing UV illumination, the composite containing 4 wt% Ti₃C₂T_x with the highest oxygen vacancy ratio and the largest specific surface area among all the Zn₂SnO₄/TiO₂/Ti₃C₂T_x heterostructured composites exhibits the strongest sensitivity to n-hexanol. Its sensitivity is 2.9 times higher than that without UV illumination, accompanied by rapid response and recovery times (72/61 s). Additionally, the optimal working temperature of the composite is reduced by 55 °C after UV illumination. Detailed materials characterization and gas sensing measurements reveal that the enhanced n-hexanol sensing performance is attributed to the synergistic effect between the heterostructured phases and the UV-activated photocatalytic properties of TiO₂. Overall, this study provides new insights into the fabrication of high-performance metal oxide-based gas sensors by the modulation of the oxygen vacancy concentration and photocatalytic activity of the sensing material.