Fast-response and highly sensitive formaldehyde sensor at room temperature based on ZnO/TiO2/rGO hybrids

In this work, we synthesized the ternary nanocomposite of ZnO/TiO 2 /rGO and used as formaldehyde gas detection at room temperature (RT). The integration of rGO with the ZnO/TiO 2 heterostructure enhanced the composite’s responsiveness at RT. The presence of rGO enhanced conductivity, mechanical stability, and charge transfer, in addition to providing more active sites for CH 2 O molecule adsorption. Sensors based on ZnO/TiO 2 /rGO exhibited a response of 86 to 50 ppm formaldehyde, with response and recovery times significantly shortened to 11 s and 3 s, respectively. Additionally, the selectivity, stability, and repeatability of the sensors were also evaluated. Our method of sequentially combining ZnO with TiO 2 , followed by incorporating rGO to form a ternary heterostructure, effectively optimizes ZnO. This two-step approach addresses the limitations of slow desorption efficiency and low response associated with ZnO. We conducted first-principles computation to understand the sensing performance.