Fabrication of p-Type Co₃O₄ Nanofiber Sensors for Ultra-Low H₂S Gas Detection at Low Temperature.

Abstract

In the current work, we report the on-chip fabrication of a low-temperature H₂S sensor based on p-type Co₃O₄ nanofibers (NFs) using the electrospinning method. The FESEM images show the typical spider-net like morphologies of synthesized Co₃O₄ NFs with an average diameter of 90 nm formed on the comb-like electrodes. The EDX data indicate the presence of Co and O elements in the NFs. The XRD analysis results confirm the formation of single-phase cubic spinel nanocrystalline structures (Fd3 m) for the synthesized Co₃O₄ NFs. The Raman results are in agreement with the XRD data through the presence of five typical vibration modes of the nanocrystalline Co₃O₄. The gas sensing properties of the fabricated Co₃O₄ NF sensors are tested to 1 ppm H₂S within a temperature range of 150 °C to 450 °C. The results indicate a highest sensor response to 1 ppm H₂S with the gas response of aproximately 2.1 times and the gas response/recovery times of 75 s/258 s at a low temperature of 250 °C. The fabricated sensor also demonstrates good selectivity and a low detection limit of 18 ppb. The overall results suggest a simple and effective fabrication process for the p-type Co₃O₄ NF sensor for practical applications in detecting H₂S gas at low temperature.