Ti 3 C 2 T x /SnO 2 P–N heterostructure construction boosts room-temperature detecting formaldehyde

Formaldehyde is a common atmospheric pollutant produced in industrial production and daily life. However, the traditional semiconductor formaldehyde gas sensor cannot work at room temperature, which limits its practical application. Therefore, developing high-performance gas sensors for rapidly and accurately detecting formaldehyde at room temperature is an important topic. In this study, Ti 3 C 2 T x /SnO 2 heterostructures were constructed, which could selectively detect formaldehyde at room temperature with a response value of 29.16% (10 × 10 –6 ). In addition, the sensor shows a remarkable theoretical detection limit of 5.09 × 10 –9 and good long-term stability. Density functional theory (DFT) simulations reveal that SnO 2 nanospheres provide the majority of adsorption sites that strongly interact with formaldehyde. Meanwhile, Ti 3 C 2 T x acting as a conductive layer facilitates the transfer of charge carriers so that they show a sensing response to formaldehyde at room temperature. Moreover, the formation of p-n heterostructures between SnO 2 and Ti 3 C 2 T x boosts the Schottky barrier at the interface, which is the critical factor in enhancing the sensing properties by turning the Schottky barrier upon introducing formaldehyde gas. This perspective is expected to provide instructive guidance for utilizing MXene/metal oxide nanocomposites to improve the gas sensing performance at room temperature. Graphical abstract