Study of Band Gap of Silver Nanoparticles—Titanium Dioxide Nanocomposites

Abstract

The optical and chemical properties of Ag/TiO2nanocomposites were investigated to explore the possibilities of incorporating these new materials in Gratzel photoelectrochemical cells. The nanocomposites were obtained doping TiO2, in both allotropic species anatase and rutile, with silver nanoparticles (grown by laser ablation process). X-ray photoelectron data indicate the absence of Ag-Ti chemical bonds, while measurements of photoluminescence and optical absorbance in UV-visible range show a quench in photoluminescence emission of about 50% and an increase in visible absorbance of about 20%. Measurements of optical band gap, obtained by Tauc’s equation, indicate a variation of about 1.6 eV.

Structural and Optical Properties of Ag Nanoparticles Synthesized by Thermal Treatment Method

“…Since it can be seen that some of the absorption spectra have a wide peak, therefore, the conduction band energy of Ag nanoparticles can also be calculated indirectly from the absorption spectra by the following Tauc’s equation:${false(\mathrm{sans-serif\alpha }h\nu false)}^2=B\left(h\nu -E_{\mathrm{cb} }\right)$ where α is the absorption coefficient, hv is the photon energy, E cb is the conduction band energy, and B is a constant. According to this equation, by plotting the (α hν ) 2 versus ( hv ) and extrapolation of the linear part of the curve to the energy axis, the conduction band energy of Ag nanoparticles can be achieved as shown in Figure 8 [59,60]. It is obvious from the Figure 8 that by increasing the calcination temperatures from 400 to 800 °C the conduction band energy increased from 2.75 to 3.04 eV, respectively.…”

Ag modified ZnS for photocatalytic water pollutants degradation: Influence of metal loading and preparation method

“…The further increase in Ag loading (2Ag and 4Ag samples) caused a reduction of the calculated E bg , being equal to 2.1 and 1.8 eV, respectively. The observed strong decrease of E bg for 2Ag and 4Ag may be due to the high concentration of Ag nanoparticles on ZnS surface [53]. This drastic decrease in E bg can also explain the changes in UV-visible absorption properties and clearly indicates a progressive metallization of the samples caused by the Ag [53].…”

Influence of Poly(vinylpyrrolidone) concentration on properties of silver nanoparticles manufactured by modified thermal treatment method

“…Because some of the absorption spectra have a wide peak, calculating the conduction band energy of produced silver nanoparticles indirectly from the absorption spectra by the following Tauc’s equation was also tried: Where α is the absorption coefficient, hv is the photon energy, E cb is the conduction band energy, and B is a constant. According to this equation, by plotting the ( αhν ) 2 versus ( hv ) and extrapolation of the linear part of the curve to the energy axis, the conduction band energy of Ag nanoparticles can be achieved, as shown in Fig 6 [ 85 , 95 ]. It is obvious from Fig 6 that by increasing the PVP concentration from 2% to 4%, the conduction band energy increased from 2.83 to 2.94 eV.…”