Oxalic acid-derived combustion synthesis of multifunctional nanostructured copper oxide materials

Abstract

Combustion-derived synthesis of nanostructured copper oxide (CuO) materials was synthesized by oxalic acid as a fuel, and copper nitrate as an oxidant. The combustion product showed mixed phases of CuO and Cu 2 O. The pure nanocrystalline CuO phase was obtained upon subsequent annealing of the combustion product at 700 °C for 3 h, whereas the planetary ball-milling of the combustion product at 300 rpm for 10 h yielded CuO phase with two weak peaks of Cu 2 O phase. The microstructural and optical properties of CuO nanomaterials were explored by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR), near infrared (NIR), and diffused reflectance spectroscopic (DRS) techniques. The annealed powder XRD pattern confirms that it crystallizes in a monoclinic C12/c1 (15) structure with lattice parameters: a = 0.4687( 4), b = 0.3419(3), c = 0.5128(4) nm, and β = 99° 39′ (4) with average crystalline size, D of 30.89 nm. The agglomeration of fine particles is seen for the ball-milled powder, while the annealed powder revealed different particle sizes in the range of 254 ~ 835 nm as evidenced from FESEM images. The NIR reflectance of (~ 45%) CuO powder (annealed) can be used as black pigments in color industries. The annealed CuO powder reveals narrow Raman peaks than ball-milled powder.

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

“…While comparing/observing the XRD patterns, we conclude that hexamine, urea, and glycine fuels yielded phase pure CuO powder, whereas sucrose fuel produced nearly a single phase of CuO powder except a weak peak noted at 2θ = 36.43°due to Cu 2 O phase. 37 The other fuels for instance aniline, citric acid monohydrate, dextrose, and oleic acid revealed mixed phases of CuO and Cu 2 O. Among these fuels, dextrose and aniline showed a maximum level of Cu The observed peak intensity of the impurity phase, Cu 2 O is varied with the used different fuels such as urea, sucrose, dextrose, aniline, oleic acid, and citric acid monohydrate.…”

“…52 For the different CuO powder, the Raman spectra were taken from the Horiba Jobin-Yvon LabRam HR800, spectrometer using He-Ne as a laser source (632.8 nm). 37 Jasco-v-670 NIR spectrophotometer was used to check the absorbance and reflectance efficiency of CuO powder. The FESEM micro-images and EDX analysis for the CuO powder obtained from the fuels, glycine, and urea were taken from the Inspect F FESEM (20 kV) equipped with Energy Dispersive X-ray Spectrometer, whereas, FEI Quanta FEG 200 attached with EDS analyzer was used for the CuO powder obtained from hexamine fuel.…”

“…The physicochemical properties of CuO nanomaterials have been explored by changing the preparation conditions and other parameters by the research community via a combustion synthesis method [23][24][25][26]37 using glycine, 23,24 citric acid, 25 malic acid, 26 and oxalic acid 37 as fuels. From the literature, we learned that different fuels have shown somewhat different results.…”

“…This may be due to the difference in the conditions employed by the researchers. [23][24][25][26]37 Further, we believe that the type of fuel has a different effect on the formation of different types of oxide phases owing to the fuel efficiency, selection of oxidizer (metal precursor), temperature of the combustion reaction, method of ignition, ignition temperature, the amount of gases released, generated heat energy, etc. [39][40][41][42][43][44][45][46][47][48][49][50][51] According to the report of Lutukurthi et al, 42 the ignition temperatures were below 400 °C for the combustion syntheses of simple oxides.…”

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

“…Such a decrease in NIR reflectance of the ball-milled materials is significantly noted in different types of oxides. 47,48,[50][51][52][53][54][55][56] While the commercial Cr 2 O 3 powder is green, 40 the other produced samples are different in color appearance (figure not shown here). The difference in color appearance shows a significant variation in NIR reflectance values (Fig.…”