Abstract:
The increase of environmental pollutions from industry due to organic dye effluents initiated the
researcher to design a nanomaterial with a target of photocatalytic degradation capacity. So, the
main objective of this thesis was to synthesize Ag-ZnO NCs using Psidium guajava leaf extracts
and evaluate its photocatalytic activity. A simple, ecofriendly, inexpensive, short-time consumer
and biocompatibility approach was developed for the synthesis of Ag-ZnO NCs using P. guajava
leaf extract without employing any chemical stabilizer. The phytochemical screening analysis of
the plant extract confirmed the presence of alkaloids, flavonoids, phenols, tannins and saponins.
The synthesized crystalline nanoparticles were characterized by UV-Vis, FT-IR and XRD. The
UV-Vis absorbance peak for ZnO and Ag-ZnO were 374 and 375 nm with band gap of 3.02 and
2.86 eV respectively. The FT-IR result showed the presence of functiona groups in the leaf
extract and prepared nanoparticles. Furthermore, a good coordination of functional groups with
the synthesized NPs were observed as it displayed red-shift of absorbance peaks. The XRD data
revealed that the average crystalline size of ZnO and Ag-ZnO were 22 and 26 nm, resperctively.
Photocatalytic activity of Ag-ZnO NCs was performed under natural sunlight using methylene
blue as organic dye pollutant. The dye was entirely decolorized and degraded by more than 98%
after irradiation for 120 min. In contrast, the solar light catalyzed dye was not decolorized still it
was irradiated upto 200 min. Therefore, the present study provided that the Ag doped ZnO
nanocomposites may have good applications and high-efficiency of photocatalytic activity
