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

Abstract

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.

Gold-selenide quantum dots supported onto cesium ferrite nanocomposites for the efficient degradation of rhodamine B

“…These differences in the nanomaterial's properties are due to differences in their size, shape and surface area with advancement in nanotechnology [ 7 ]. Quantum dots (QDs) [ 8 , 9 ] have been attracted more attention of chemical researchers, may be due to their unique catalytic/photocatalytic capability in the chemical catalysis and the photocatalysis processes [ 10 , 11 , 12 , 13 ]. The QDs have been extensively applied in the fields of environmental treatment/water treatment, chemical industry, sensors, solar cells, electronics, optoelectronics devices, cosmetics, drug delivery systems, and biological processes [ 10 , 14 , 15 , 16 , 17 , 18 ].…”

One-step preparation of RGO/Fe3O4–FeVO4 nanocomposites as highly effective photocatalysts under natural sunlight illumination

“…However, the absorption in the visible region (strong red-shift) improved largely in the xRGO/Fe 3 O 4 –FeVO 4 comparing with Fe 3 O 4 –FeVO 4 indicating improving the optical properties Fe 3 O 4 –FeVO 4 when composed with RGO 45 . The band gap energy (E g ) was calculated using Tauc’s equation: where υ is the wavenumber, h is Planck constant, α is absorption coefficient, E g is the energy band gap and A is a constant 9 , 29 . From the plot of (αhυ) 1/2 versus photon energy (eV) as shown in Fig.…”

Photocatalytic Degradation of Methylene Blue under Visible Light Using TiO2 Thin Films Impregnated with Porphyrin and Anderson-Type Polyoxometalates (Cu and Zn)

“…It consists of the irradiation of a catalyst surface with enough energy to generate photoexcitation, producing highly oxidizing species that allow the degradation or mineralization of pollutants on a liquid or gaseous phase [3]. In photocatalysis, semiconductors (e.g., SnO 2 , ZnO or TiO 2 [4]) and hybrid materials (quantum dots, composites [5][6][7]) are usually used as the active phase. The TiO 2 surface chemical properties rely on the electronic properties of the semiconductor surface, and it is one of the reasons for its high interest in photocatalytic applications [8].…”