Precision Gas Sensing: Tuning The Defect Energy Level of SnO₂ Nanofiber Devices by Surface Defect Engineering

In the last decade, surface defect engineering in metal oxide semiconductor materials is gaining more attention since it provides controllability and opens up possibilities for commercial use in various fields like gas sensors, photocatalysis, nanoparticle filters and so much more.<br/>In this work, the enhancement of gas detection ability of SnO₂ nanofiber devices (NFDs) can be achieved by using electrospinning and surface defect engineering. Increasing surface area can provide more reaction centers for gas molecules, so as to boost the detection ability of SnO₂ NFDs by colloidal film deposition. With colloidal film deposition, the sensitivity of NO gas (less than 50 ppb) detection can be increased more than three times. Furthermore, specific gas molecules can be detected by tuning the surface defect energy through nano-heterojunction integration. This is due to the variation in absorption energy among different gases. To investigate the density of states and to control the energy levels of defects, the X-ray absorption near edge structure (XANES) spectrum and Raman spectrum were used to measure SnO₂NFDs. Based on the XANES results, the out of plane and in plane oxygen defects can be varied significantly by surface engineering.<br/>In summary, through surface defect engineering techniques, we have acquired the capability to fully control the characterization and distribution of surface defects in SnO₂ NFDs. Combining with the nanoscale advantage, we can realize low-concentration gas sensing with high precision.