Enhanced photocatalytic degradation of RhB dye from aqueous solution by biogenic catalyst Ag@ZnO

Highlights: • Ecofriendly synthesis of Ag decorated ZnO nanoparticles was carried out. • Carya illinoinensis leaves extract was used as reducing and capping agent. • Decoration of Ag increased the photocatalytic activity due to trapping of electrons. • The effect of various factors were examined, degradation kinetic of dye (Rhodamine B) obeyed pseudo first order model. -- Abstract: In the present work, ZnO and Ag@ZnO nanoparticles based photocatalyst were synthesized via green route by using the leaves extract of pecan nuts (Carya illinoinensis) for the first time. The phytochemicals present in leaf of extract pecan nuts (Carya illinoinensis) such as methyl gallate and kaempferol act as capping and reducing agents. The obtained photocatalyst were analyzed via various techniques such as XRD (X-ray diffraction), TEM (transmission electron microscopy), SEM (scanning electron microscopy), FTIR (Fourier transform infrared spectroscopy), PL (Photoluminescence spectroscopy), XPS (X-ray photoelectron spectroscopy) and UV (UV–visible spectroscopy). The activity of biogenic photocatalyst were investigated against RhB (Rhodamine B) dye and the results demonstrated that the catalytic properties become enhanced significantly after Ag doping as compared to bare ZnO. The effect of various parameters were also investigated such as pH, catalyst dose, initial concentration of dye. The obtained results showed highest efficacy of catalyst at pH 10, further the photo-degradation of Rhodamine B (RhB) dye followed pseudo first order kinetic model. The reusability test of biogenic photocatalyst revealed that the catalyst was an excellent option for practical use with high stability even after 5 cycles. The mechanism for, ZnO and Ag@ZnO synthesis and degradation pathway of RhB dye was proposed.