Template based sintering of WO3 nanoparticles into porous tungsten oxide nanofibers for acetone sensing applications

Abstract

Porous WO₃ nanofibers have been synthesized by electrospinning polyvinylpyrrolidone (PVP) nanofibers embedded with semiconducting WO₃ nanoparticles followed by annealing in air. PVP serves as a template in sintering of WO₃ nanoparticles into nanofibrous morphology. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations have revealed a highly porous structure of WO₃ nanofibers with diameters in the range of 800–1200 nm. Fourier transform infrared spectroscopy (FTIR) confirms complete removal of the polymer from the porous WO₃ NFs after annealing. Amperometry based sensing performance of porous WO₃ nanofibers is evaluated toward low concentrations (1.8–12.5 ppm) of acetone and further improved via light excitation (365 nm UV) and applied bias voltage (3–7 V). The applied bias voltage has a significant effect on sensor characteristics with a remarkably enhanced response at a higher bias voltage. A maximum response (I_gas–I_air) of 1.79 μA is obtained at 7 V bias voltage toward 12.5 ppm acetone at 350 °C under UV irradiation. The porous WO₃ nanofibers are able to detect 700 ppb of acetone with 3 V bias voltage using photo-activation with a response/recovery time of 33 s/42 s and excellent repeatability. The experimental results confirm the potential usage of the developed sensor based on electrospun porous WO₃ nanofibers for acetone sensing applications.