Undoped and Mn-doped Co3O4 nanorods for ethanol sensing

Abstract

Undoped and Mn-doped (1 at.%) Co 3 O 4 were synthesized by simple precipitation method. The morphology of the material was investigated by scanning electron microscopy which confirmed the formation of nanorods (NRs). The NRs were formed from interconnected nanoparticles. X-ray diffraction analysis confirmed the presence and crystalline nature of the Co 3 O 4 NRs. FTIR studies revealed that the defects are present in undoped Co 3 O 4 . Raman spectra confirmed the presence of five Raman active modes and the doping of Mn shifts the Raman peaks to higher wave number. Spectral responses of clad modified fiber optic gas sensor are studied for various concentrations (0-500 ppm) of ethanol at room temperature, where the clad portion is replaced with undoped and Mn-doped Co 3 O 4 and used as gas sensing material. Since the refractive index of the samples calculated from UV-Vis absorption spectra is greater than that of core, the fiber optic sensor works under leaky mode condition. The sensor showed linear variation in the spectral peak intensity with ethanol concentration. Undoped Co 3 O 4 exhibits higher sensitivity compared to Mn-doped Co 3 O 4 due to defects present in the undoped sample which offers more reactive sites for ethanol adsorption.

Fiber-Optic Chemical Sensors and Biosensors (2013–2015)

“…These also can detect ethanol via a decrease in their absorbance on exposure to alcohol vapor. In the case of Co 3 O 4 nanorods, the undoped nanorods exhibit even higher sensitivity than the Mn-doped Co 3 O 4 nanorods …”

“…Similar to the SnO 2 and SnO 2 /CuO, other kinds of inorganic nanoparticles were tested. These are made from Li 2 B 4 O 7 that was doped with Co and Cu, or Gd-doped ZnO nanoparticles, or both undoped and Mn-doped Co 3 O 4 nanorods . These also can detect ethanol via a decrease in their absorbance on exposure to alcohol vapor.…”

CADMIUM-DOPED Co3O4 THIN FILMS: SYNTHESIS AND CHARACTERIZATION

“…The other band at about 660 cm À1 is associated to the vibrational coupling linked to the two bonds formed by Co 3þ and Co 2þ present in the tetrahedral holes. 26 The peaks at around 1625 and 3600 cm À1 in the spectrum of Co 3 O 4 are assigned to molecular water and O-H; peak at 2375 cm À1 characteristic of the carbonyl group indicates the presence of the carbon dioxide molecules of the air. The peak at 1450 cm À1 is corresponding to the stretching vibration of NO À 3 , which is due to the residue of Co (NO 3 Þ 2 .…”

“…The samples with a doping percentage of 3% and 5% were shown to have the greatest absorbance, which means that these two samples were the most inserted in the thin layer's matrix. 26 Figure 4 illustrates the XRD patterns of undoped and Cd-doped Co 3 O 4 calcined at 400 C for 3 h to start the formation of nanocrystalline phases. The spectra illustrate di®raction peaks corresponding to the planes (220), (311), (222), (400), (511) and (440) with preferred orientation (311).…”

Enhanced Gas‐Sensing Performances of Ru‐Loaded p‐Type Co3O4 Nanoparticles

“…It is also well‐known as an excellent catalyst for oxidation of ethanol . Hence, Co 3 O 4 should be a promising material for detection of ethanol vapor …”