Design and construction of bio carbon derived Bi2Fe4O9 nanocomposites sensor for clad modified optical fiber sensors for detection of ethanol gas

Abstract

Bio carbon (BC) derived Bi2Fe4O9 hybrid sensor was fabricated via sonochemical approach. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and N2 adsorption-desorption were used to determine the structural, morphological and porosity characteristics, respectively. The materials' gas-sensing properties were evaluated using a clad-modified optical fiber sensor. The orthorhombic structure with Pbam space group of Bi2Fe4O9 confirmed by the relative diffraction pattern. All sharp intense diffracted patterns might be indexed based on the standard value ((JCPDS card No. 74-1098). Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images illustrate those granular sheets with aggregated spherical shaped morphology of BC and Bi2Fe4O9, respectively. The pristine Bi2Fe4O9 exhibits Raman modes at 378 cm−1 and 617 cm−1, which is ascribed to the orthorhombic structure. The orthorhombic structure was already confirmed from XRD results. BFOG5 sample shows high SSA (107.5 m2/g) and pore size (38.4 nm), which is nearly 2.2 times greater than that of pristine Bi2Fe4O9 (54.3 m2/g and 23.4 nm). Fiber optic sensor was fabricated and tested for ethanol gas with various gas concentrations (0–500 ppm). The sensitivity (defined as slope of fitted line) enhanced from 14.69 (count/%) for bare Bi2Fe4O9 to 33.94 (count/%) for Bi2Fe4O9/BC (BFOG5). The response and recovery time was 25 s and 20 s for Bi2Fe4O9/BC (BFOG5) sensor, which is higher than that of bare Bi2Fe4O9 (42 s and 33 s). Our findings pave the way for a unique hybrid Bi2Fe4O9/BC composite to be used in a highly sensitive C2H5OH gas sensor system at RT.

Keywords

• Fiber optic gas sensor
• Bio carbon
• Bi2Fe4O9
• Ethanol gas
• Evanescent wave