Diffusion-controlled growth of CuAl ₂ O ₄ nanoparticles: effect of sintering and photodegradation of methyl orange

Facile synthesis of CuAl2O4 and sintering effects on the phase composition are reported. Annealing at 500 °C showed only CuO phase and the spinel phase started evolving at 700 °C with the concurrent decrease in the CuO phase. Diffusion-mediated growth of spinel phase was also observed at higher temperatures forming CuAl2O4 at 1000 °C. The material was stoichiometric and the average particle size was 55 nm, as evidenced by EDS and FE-SEM studies, respectively. The zeta potential of +30 mV and lower (0.346) value of the poly dispersive index (PDI), confirmed the high dispersability of CuAl2O4 in water. The favourable band gap (2.2 eV) makes it suitable as visible light photocatalyst. Owing to its positive surface charge and conducive pH, material could adsorb anionic methyl orange dye. A total of 74% of the dye could be recovered by a simple methanolic extraction. The visible light photocatalysis of the same dye leads to 67% decolouration and the addition of H2O2 accelerated the photodegradation to completion. The catalyst displayed excellent reusability and stability even after five successive runs.