A novel ethanol gas sensor based on α-Bi₂Mo₃O₁₂/Co₃O₄ nanotube-decorated particles

A novel composite based on α-Bi₂Mo₃O₁₂/Co₃O₄ nanotube-decorated particles was successfully synthesized using a highly efficient and facile two step system using electrospinning and hydrothermal techniques. The small size Co₃O₄ nanoparticles were uniformly and hydrothermally developed on the electrospun α-Bi₂Mo₃O₁₂ nanotubes. The pure α-Bi₂Mo₃O₁₂ nanofibers and composite based on α-Bi₂Mo₃O₁₂/Co₃O₄ were examined using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analyses. From the BET measurements, the composite based on α-Bi₂Mo₃O₁₂/Co₃O₄ exhibits a large specific surface area of 54 m² g^-1 with mesopore diameter ranges of 2-10 nm, which is mainly attributed to the remarkable and dominant enhancement in gas sensing as compared to that of the pure α-Bi₂Mo₃O₁₂ nanofibers (38 m² g^-1) and Co₃O₄ nanoparticles (32 m² g^-1), respectively. In this work, the novel composite based on α-Bi₂Mo₃O₁₂/Co₃O₄ presented a high sensitivity of 30.25 with a quick response/recovery speed towards 100 ppm ethanol at an optimal working temperature of 170 °C, as compared to the pure α-Bi₂Mo₃O₁₂ nanofibers and Co₃O₄ nanoparticles, which display a sensitivity of 13.10 and 2.99 at an optimal working temperature of 220 °C and 280 °C. The sensing performance of the composite based on the α-Bi₂Mo₃O₁₂/Co₃O₄ sensor exhibits a superior sensing performance towards ethanol, which might be owed to the enormous number of superficial oxygen species, the small size catalytic effect of the Co₃O₄ nanoparticles and the interfacial effect formed between the n-type α-Bi₂Mo₃O₁₂ and p-type Co₃O₄ leading to a high charge carrier concentration. This is a novel investigation of a composite based on an α-Bi₂Mo₃O₁₂/Co₃O₄ sensor in the gas sensing era, which might be of vital importance in applications in the advanced gas sensing field.