Electrospun ZnO-SnO2 heterojunction belts for hydrogen sensing

Chemiresistive sensors are promising devices for sensing hydrogen gas in a broad range of applications including fuel cells, hydrogen storage systems, petroleum refinement, and diagnosis of oil-insulated transformers. Herein, electrospun ZnO-SnO2 belts (BLs) were synthesized and applied as resistive-type sensing layers for hydrogen sensing. The ZnO-SnO2 BLs containing 20 mol% of Zn relative to Sn showed a response (R-a/R-g, R-a: resistance in air, R-g: resistance in target gas) of 6.7, fast response speed (3.6 s), and a distinguishable selectivity toward 5 ppm of hydrogen at 400 degrees C in the presence of formaldehyde, methane, ammonia, carbon monoxide, and carbon dioxide gases. The sensor displayed a repeatable response when subjected to 15 cycles of alternate air and 5 ppm hydrogen exposure. A unique hydrogen sensing performance of the BLs was attributed to their belt morphology, numerous surface pores, smaller crystal size, ZnO/SnO2 heterojunction, and ZnO metallization following hydrogen exposure. The present synthetic method paves the way for generating microstructures with smaller diffusion length that overcomes the shortcomings of non-porous and/or thick materials while providing a potential platform for reliable and enhanced hydrogen sensing.

Automated summary

In this study, nanoscale ZnO-SnO2 belts were synthesized and applied as resistive-type sensing layers for hydrogen sensing. The ZnO-SnO2 belts exhibited high response, fast response speed, and distinguishable selectivity towards 5 ppm hydrogen at 400 degrees C in the presence of other gases. The sensor demonstrated stability and repeatability through 15 cycles of alternate air and hydrogen exposure. The unique sensing performance of the ZnO-SnO2 belts can be attributed to their belt morphology, surface pores, smaller crystal size, ZnO/SnO2 heterojunction, and ZnO metallization following hydrogen exposure.