Combustion Synthesis of CuO Nanomaterials: Effect of Different Fuels on the Structural, Thermal, and Optical Properties

Abstract

The wet chemical combustion synthesis and the effect of different (aniline, citric acid monohydrate, dextrose, glycine, hexamine, oleic acid, sucrose, and urea) fuels on the combustion products of CuO nanomaterials are reported for the first time as a comparative study. The pure nano-sized CuO phase combustion products were produced from hexamine, urea, and glycine as fuels, whereas fuel-like sucrose yielded nearly a single phase of the CuO combustion product. The quality of the combustion products revealed mixed phases of CuO and Cu2O for aniline, dextrose, citric acid monohydrate, and oleic acid as fuels. The pure combustion products crystallized in a monoclinic structure with a space group, C12/c1 (15). For the mixed phases of combustion products, weight gain (102.5%–109%) is noted >400 °C in the TG curves owing to the oxidation of the Cu2O phase into the CuO phase. The bandgap of the different CuO powder was in the range of 2.1–2.6 eV. From the NIR spectra, we conclude that the nanocrystallinty of the CuO phase plays a major role in the enhancement (∼35%) of NIR reflectance owing to the difference in the fuels used. The observed Raman modes confirm the characteristics of the CuO phase. Different morphologies are observed for the different CuO combustion products obtained from hexamine, urea, and glycine as fuels.

Detailed Studies on the Synthesis Methods and Characterizations of Nanocrystalline Cr2O3 Phase Materials for NIR Pigmentation Applications

“…Characterization techniques.-The different processed samples were examined by the XRD technique using Cu K α radiation (BRUKER diffractometer). 37 The TG and DTA were performed in air atmosphere in a thermal analysis system. The diffused reflectance spectroscopy (DRS) was used to analyse the spectral features of different Cr 2 O 3 samples in the ultraviolet-visible-near-infrared (UV-Vis-NIR) regions, 200-2500 nm.…”

“…The UV-Vis-NIR spectral features of different Cr 2 O 3 samples were measured in both absorbance and reflectance modes in the instrument JASCO spectrophotometer using the light source of D2/WI. [37][38][39] The FT-IR spectral features of the samples were scanned in the FT-IR spectrometer (Nicolet iS50/Thermo Fisher Scientific) in transmittance ATR mode. 38,39 The Raman spectra were scanned in the range 80 to 1000 cm −1 using He-Ne as a laser source (632.8 nm) in the Horiba Jobin-Yvon LabRam HR800 spectrometer.…”

“…38,39 The Raman spectra were scanned in the range 80 to 1000 cm −1 using He-Ne as a laser source (632.8 nm) in the Horiba Jobin-Yvon LabRam HR800 spectrometer. [37][38][39] The micro-images (FESEM) and elemental analysis (EDX) of the Cr 2 O 3 phase nanomaterials were taken from the Inspect F FESEM equipment. [37][38][39] Results and Discussion XRD.-Figure 5 represents the XRD patterns of precursor salt, Cr(NO 3 ) 3 .9H 2 O and the thermally treated precursor to see the phase formation of Cr 2 O 3 and its purity at different temperatures, 200 °C-900 °C.…”

“…[37][38][39] The micro-images (FESEM) and elemental analysis (EDX) of the Cr 2 O 3 phase nanomaterials were taken from the Inspect F FESEM equipment. [37][38][39] Results and Discussion XRD.-Figure 5 represents the XRD patterns of precursor salt, Cr(NO 3 ) 3 .9H 2 O and the thermally treated precursor to see the phase formation of Cr 2 O 3 and its purity at different temperatures, 200 °C-900 °C. While screening the XRD patterns illustrated in Figs.…”

“…The Cr 2 O 3 materials obtained above 350 °C indicate the rhombohedral structure with space group, R-3c h (167) and the indexing of the peaks are done for the same crystal system by analyzing the XRD data using Jana program. [37][38][39][40] XRD patterns of wet chemical (precipitation and hydrothermal) synthesized as-prepared and annealed samples along with ballmilled commercial Cr 2 O 3 powder are depicted in Fig. 6.…”