On-chip CuFe2O4 nanofiber for conductometric NO2 and H2S gas-sensors

xCuO-(1-x)Fe2O3 composite nanofibers (NFs) for gas-sensing applications were thoroughly investigated in this work employing on-chip electrospinning. The fabricated NFs had a characteristic spider-net-like morphology and had diameters of 50–100 nm. The NFs composed of nanograins with diameters ranging from 16 to 35 nm have multi-porous structures. The composite NFs enhanced sensor response compared to that of single metal oxides. At the optimal composition of 0.5CuO-0.5Fe2O3 NFs, which formed a complex oxide of copper ferrite (CuFe2O4), the sensor showed the highest response (15.3 and 10) to 1 ppm H2S gas at 350 °C and 10 ppm NO2 gas at 300 °C, respectively. Additionally, the detection of on-chip NF sensors to target gases was considerably impacted by the electrospinning time. The maximum response to H2S gas was achieved after 30 min of the electrospinning process, while that to NO2 gas is 10 min. The enhanced gas-sensing performance was attributed to nanograin-based NF structure, the formation of binary complex CuFe2O4 oxide, and the heterojunctions between CuFe2O4 and single oxide (CuO or α-Fe2O3) in composite NFs. Furthermore, the high sensitivity and selectivity of the CuFe2O4 NF sensor toward target gases are also discussed by using density functional theory (DFT) calculation.