Influence of Al cations insertion on the structural, morphological, optical properties, and methyl orange photocatalytic remotion of Pr-doped ZnO system

Zinc oxide is a wonder of nature because it has infinite properties. The boom of this semiconductor arises due to its versatility in optoelectronic applications and for being a hopeful material for environmental remediation. Changes in the synthesis parameters and one or more cations inclusion in the structure are alternatives used to make ZnO the most impressive semiconductor material. In this study, we synthesize and characterize the Zn1-x-yPrxAlyO system, [x, y] = (0.00, 0.00); (0.03, 0.01); (0.03, 0.03) for use in the photocatalytic discoloration of methyl orange. Variations in structural parameters are linked to the Zn2+ cations with Pr3+ and Al3+ cations replacement, as well as atomic disorder in the structure. According to Raman spectra, the E2(high) characteristic of oxygen vibration in the ZnO crystal structure undergoes a small shift toward higher wavenumbers, suggesting the oxygen defects presence. The PL spectra were fitted using a Gaussian function, and the results confirmed high zinc vacancy (VZn) and neutral oxygen vacancy (VO) concentrations in the Zn1-x-yPrxAlyO compound. In addition, the Pr3+ and Al3+ ions insertion into ZnO causes variations in the band gap and Urbach energy. The Field Emission Scanning Electron Microscopy (FE-SEM) micrographs confirmed that the samples have irregular particle clusters. The photocatalytic tests demonstrated that the dopant contributed to increased methyl orange dye (MO) discoloration, reaching values between 53.7 and 90.0% of pollutant removal. The scavenger tests suggested that the reactive species responsible for the photodegradation/discoloration mechanism of the MO dye in solution are in the next order: •O2− > •OH > e− > h+. Finally, the samples maintained structural integrity after three consecutive reuse cycles while removing 22.7% of the MO dye. This study demonstrates the viability of inserting Pr3+ and Al3+ cations into the ZnO crystal structure to improve semiconductor efficiency for environmental applications.