Exploration of CdO properties favoring superior photocatalytic degradation of methylene blue dye by Al3+ doping

Cadmium oxide (CdO) photocatalysts have been prepared using chemically controlled co-precipitation method with the intension to serve as photocatalyst in the degradation of methylene blue dye. Photocatalytic property of CdO was improved by properly undertook calcination at various temperatures 400, 600 and 800 °C, and by doping with Al 3+ to different weight percentages (0.5 and 1 wt%). The powder X-ray diffraction patterns of the synthesized CdO and Cd (1−x) Al x O samples exposed the formation of single phase polycrystalline face centered cubic (Fm 3 ¯ m) CdO structure with no impurity phases even after doping with Al 3+ . Obtained crystallite size in the range 22 to 72 nm was well suited for photocatalytic activity. The presence of Al dopant as Al 3+ ion in the CdO lattice was confirmed from the information derived from the XPS spectra. In the SEM images the revealed agglomerated spherical morphology evidenced the presence of round edges and corners that can have more active sites in the photocatalytic process so as to advance the photocatalytic activity. Direct optical band gaps measured from the UV–Vis spectra seemed to lay in the range 2.09 to 2.57 eV and were liable for the greater photocatalytic activity of the readied nanoparticles. In the photoluminescence spectra, for an excitation wavelength of 440 nm, the pure and doped CdO nanoparticles displayed bands about 485, 530 and 600 nm with poorer intensities and exposed its appropriateness to serve as superior photocatalyst. Attained good electrical conductivity of CdO and its enhancement with Al doping exposed the liableness of the samples to use as better photocatalysts. The small-sized Al doped CdO nanoparticles showed evidence of considerably high visible-light-driven photocatalytic activity for the degradation of methylene blue solution, with better degradation percentage and kinetic rate constant compared to pure CdO.