A high-response formaldehyde sensor based on fibrous Ag-ZnO/In2O3 with multi-level heterojunctions

Abstract Timely detection of formaldehyde is pivotal because formaldehyde is slowly released from the indoor decorative materials, jeopardizing our healthy. Herein, a high-response formaldehyde gas sensor based on Ag-ZnO/In2O3 nanofibers was successfully fabricated. Compared with all the control samples, the hybrid exhibits superior sensitivity (0.65 ppm-1), excellent selectivity ( ≥12.5) and durable stability (the deviation value ≤ 3%). Particularly, an ultra-high response value of about 186 towards 100 ppm of formaldehyde at 260 oC was achieved, heading the list of outstanding candidates. Additionally, the limit of detection is as low as 9 ppb. The enhanced gas sensing properties can be mainly attributed to multi-level heterojunctions (n-n heterojunction and Ohmic junction) and the “spill-over” effect of Ag, ultimately increasing the adsorption of gas molecules on the surface of sensing material. This work verifies that proper design of multi-level heterojunctions significantly upgrade the sensing performance.