Hierarchical Heterojunctions of Metal Sulfide Nanosheets/ Metal Oxide Nanofibers for an Efficient Detection of Formaldehyde

Abstract

The construction of transition metal dichalcogenides (TMDs) heterojunctions for high performance gas sensors has garnered significant attention due to their capacity to operate at low temperature. Herein, we realize two-dimensional (2D) WS2 nanosheets in situ grown on one-dimensional (1D) In2O3 nanofibers to form heterostructures for formaldehyde (HCHO) gas sensors. Capitalizing on the p-n heterojunctions formed between WS2 and In2O3, coupled with the high surface-to-volume ratio characteristic of 1D nanostructures, the WS2/In2O3 NFs sensor demonstrated a high gas response value of 12.6 toward 100 ppm HCHO at operating temperature of 140 ℃, two times greater than that of the pristine In2O3 sensor. Meanwhile, the sensor presents remarkable repeatability, rapid response/ recovery time, and good long-term stability. The superior sensing capabilities of WS2/In2O3 NFs heterojunction are attributed to the combined impact of the increased charge transfer and the presence of more sites for gas adsorption. The research endows a potent approach for fabricating TMDs heterojunctions to significantly improve the performance of gas sensors.

Keywords: Gas sensor, WS2, p-n heterojunctions, nanofibers, HCHO