Solution combustion synthesis of Cu nanoparticles: a role of oxidant-to-fuel ratio

Solution combustion synthesis technique is one of the novel techniques used to prepare nanoparticles, nanocomposite and ceramic oxides. The authors prove in this study the usefulness of the technique in producing copper nanoparticles. In solution combustion, the stoichiometric ratio, according to propellant chemistry, needs the oxidiser-to-fuel ratio to be unity. The combustion of cupric nitrate and citric acid at stoichiometric ratio results in copper nanoparticles. The copper nanoparticles were characterised by different techniques, such as X-ray diffraction, thermal gravimetry/differential thermal analyser, Fourier transform infrared, FT-Raman and scanning electron microscopy. The Cu nanoparticles get oxidised to Cu₂O slowly at 250°C and to CuO at 530°C. The combustion of the reactants with lean and rich oxidant-to-fuel ratio (O/F) ratios results in mixed phases except in the 1:0.71 ratio. The phases in lean O/F ratios were Cu, CuO, Cu₂O, whereas only CuO was present in rich O/F ratios.