Crystalline Phase Reduction of Cuprous Oxide (Cu₂O) Nanoparticles Accompanied by a Morphology Change during Ethanol-Assisted Spray Pyrolysis

Abstract

Metallic copper nanoparticles are produced by spray pyrolysis of copper nitrates with an addition of ethanol as cosolvent at 600 degrees C. Depending on the synthesis temperature, two interesting reaction pathways are found: below 525 degrees C, approximately 10% of hollow Cu(2)O parent particles are oxidized to CuO and then reduced to Cu, but at higher temperature, the remaining Cu(2)O takes a direct path to Cu, accompanied by a morphology change. These interesting reaction regimes are discussed in the aspects of phase-transformation kinetics, gas-phase and solid-phase thermodynamics, force balance, and their possible influences on structural instability. Experimental observations are fairly consistent with the predictions by the present models.

Adsorption of Thiophenic Compounds from Model Diesel Fuel Using Copper and Nickel Impregnated Activated Carbons

“…CuO decomposes at >450 °C to Cu 2 O [43] and finally decomposes to metallic copper at higher temperatures. It is also reported that Cu 2 O reduces directly to Cu at >525 °C [44].…”

The advanced removal of benzene from aerosols by photocatalytic oxidation and adsorption of Cu–TiO 2 /PU under visible light irradiation

“…However, with the further increase of the Cu/TiO 2 ratios above 6% wt, the Cu + /Cu 2+ ratios slightly decreased. The reduction of Cu 2+ into Cu + , which resulted from the incorporation of Cu ions into the TiO 2 lattice as well as from the oxalic acid cleaning and UV irradiation processes (rolled as reducing agents) led to oxygen vacancies in the TiO 2 and CuO lattice [39,40]. The formation of oxygen vacancies led to a certain degree of limitation in the Cu 2+ reduction [41].…”

Pt Catalyst over SiO2 and Al2O3 Supports Synthesized by Aerosol Method for HC-SCR DeNOx Application

“…Assynthesized catalysts nanoparticles were collected by a glass membrane filter with 1 µm pores (Milipore). More details about experimental setup are available elsewhere (Lee et al, 2007;Firmansyah et al, 2009Firmansyah et al, , 2012.…”

“…, where R g is the gas constant, F is the Faraday constant, ν + and ν -are respectively the valences of the cation and anion, and λ 0 is the limiting ionic conductance (Reid et al, 1987;Firmansyah et al, 2009Firmansyah et al, , 2012 (Reid et al, 1987;Firmansyah et al, 2009Firmansyah et al, , 2012 , η B is the solvent viscosity in cP, V A is the molar volume of solute A at its normal boiling temperature in cm 3 mol -1 , and ϕ is the association factor. As a result, the diffusion coefficient of Pt(acac) 2 in ethanol is estimated to be 4.1 × 10 -6 cm 2 s -1 and the diffusion coefficient of TEOS in water is estimated at 8.0 × 10 -6 cm 2 s -1 .…”

“…Combining the sol-gel method with the aerosol spray-pyrolysis method (called the aerosol-gel method hereafter), we may take the unique benefits of each method (Lee et al, 2007;Firmansyah et al, 2009Firmansyah et al, , 2012, together with the advantage of costeffective production of microstructure-controlled particles (Lee et al, 1997;Santiago et al, 2011). Better understanding the process, one can extend this method to the synthesis of binary hetero-structured catalysts.…”