Enhanced photocatalytic degradation of chemical waste using Cu&Ni@FAU: insights from experimental, statistical and computational studies

In this study, a novel photocatalyst, Cu&Ni@FAU Faujasite type zeolite, was successfully prepared and characterised using various techniques, including XRD, SEM-EDX, FTIR, N2 adsorption-desorption isotherm, and UV-Vis spectrophotometry. Cu&Ni@FAU enhances the photocatalytic efficiency through several mechanisms, including the photo-Fenton-like process of H2O2, the electronic capture of KBrO3, and the reducing effect of NaBH4. Response surface methodology has been applied to study the impact of H2O2, KBrO3, and NaBH4 and their interactions on the photocatalysis of tetracycline. Furthermore, the efficiency of the photocatalysts and their kinetics were assessed for four different organic molecules, and it was found that the rate constant of tetracycline degradation was 0.054 M−1min−1. It is worth mentioning, Cu&Ni@FAU is temperature stable and shows maximum degradation at 70°C. Radical trapping experiments revealed that various reactive species played a role in the photodegradation process. The results show that hydroxyl radicals (OH•) and superoxide radicals (O2-•) are the dominant species in the photocatalysis mechanism. Additionally, electrons (e-) and holes (h+) had a moderate impact as active species, since the band edges of Cu&Ni@FAU is located between 2.86 eV at valance band (VB) and −0.38 eV at conduction band (CB).. To gain deeper insights into these processes, the study used density functional theory (DFT) simulation, which allowed for the calculation of electronic and vacuum band edges. This computational approach likely provided valuable information about the fundamental processes occurring during the photocatalysis process.