Facile and Green Synthesis of Silver Quantum Dots Immobilized onto a Polymeric CTS–PEO Blend for the Photocatalytic Degradation of p-Nitrophenol

High Resolution Image Download MS PowerPoint Slide Immobilization of inorganic metal quantum dots (especially, noble transition metals) onto organic polymers to synthesize nanometal–polymer composites (NMPCs) has attracted considerable attention because of their advanced optical, electrical, catalytic/photocatalytic, and biological properties. Herein, novel, highly efficient, stable, and visible light-active NMPC photocatalysts consisting of silver quantum dots (Ag QDs) immobilized onto polymeric chitosan–polyethylene oxide (CTS–PEO) blend sheets have been successfully prepared by an in situ self-assembly facile casting method as a facile and green approach. The CTS–PEO blend polymer acts as a reducing and a stabilizing agent for Ag QDs which does not generate any environmental chemical pollutant. The prepared x wt % Ag QDs/CTS–PEO composites were fully characterized through X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis, and UV/visible spectroscopy. The characterization results indicated the successful synthesis of the Ag QDs/CTS–PEO composites by the interactions and complexation between x wt % Ag QDs and CTS–PEO blend sheets. TEM images revealed small granules randomly distributed onto the CTS–PEO blend sheets, indicating the immobilization of Ag QDs onto CTS–PEO composites. The presence of a surface plasmon resonance (SPR) band and the shifting of the absorption edge toward higher wavelengths in the UV/vis spectra indicated the formation of x wt % Ag QDs/CTS–PEO composites. The Ag QDs in the polymeric blend matrix led to remarkable enhancement in the optical, thermal, electrical, and photocatalytic properties of x wt % Ag QDs/CTS–PEO composites. The photocatalytic efficiency of the prepared composites was evaluated by the photodegradation of p -nitrophenol (PNP) under simulated sunlight. The maximum photocatalytic degradation reached 91.1% efficiency within 3 h for the 12.0 wt % Ag QDs/CTS–PEO photocatalyst. Generally, the Ag QDs immobilized onto CTS–PEO blend composites significantly enhance the SPR effect and the synergistic effect and reduce the band gap, leading to a high photocatalytic activity.