Herein, Fe-doped C3N4 high-performance photocatalysts, synthesized by a facile and cost effective heat stirring method, were investigated systematically using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurement, X-ray photoelectron (XPS), UV–Vis diffusion reflectance (DRS) and photoluminescence (PL) spectroscopy. The results showed that Fe ions incorporated into a g-C3N4 nanosheet in both +3 and +2 oxidation states and in interstitial configuration. Absorption edge shifted slightly toward the red light along with an increase of absorbance in the wavelength range of 430–570 nm. Specific surface area increased with the incorporation of Fe into g-C3N4 lattice, reaching the highest value at the sample doped with 7 mol% Fe (FeCN7). A sharp decrease in PL intensity with increasing Fe content is an indirect evidence showing that electron-hole pair recombination rate decreased. Interestingly, Fe-doped g-C3N4 nanosheets present a superior photocatalytic activity compared to pure g-C3N4 in decomposing RhB solution. FeCN7 sample exhibits the highest photocatalytic efficiency, decomposing almost completely RhB 10 ppm solution after 30 min of xenon lamp illumination with a reaction rate approximately ten times greater than that of pure g-C3N4 nanosheet. This is in an agreement with the BET measurement and photoluminescence result which shows that FeCN7 possesses the largest specific surface area and low electron-hole recombination rate. The mechanism of photocatalytic enhancement is mainly explained through the charge transfer processes related to Fe2+/Fe3+ impurity in g-C3N4 crystal lattice.
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<p>Ag<sub>3</sub>PO<sub>4</sub> was prepared by the precipitation method using monobasic/dibasic phosphate salts (K<sub>2</sub>HPO<sub>4</sub>, KH<sub>2</sub>PO<sub>4</sub>, Na<sub>2</sub>HPO<sub>4</sub>, NaH<sub>2</sub>PO<sub>4</sub>) as a precipitating agent. The environment created by the precursor salts strong affected on the crystallinity and the morphology of Ag<sub>3</sub>PO<sub>4</sub>. Ag<sub>3</sub>PO<sub>4</sub> synthesized from dibasic phosphate salts exhibited pseudospherical morphology and small particle size while monobasic phosphate salts promoted crystallization, resulting in a large grain size and a very diverse grain morphology. Ag<sub>3</sub>PO<sub>4</sub> prepared from dibasic phosphate salts (K<sub>2</sub>HPO<sub>4</sub> and Na<sub>2</sub>HPO<sub>4</sub>) exhibited superior photocatalytic ability, completely degrading rhodamine B (RhB) in 8 min and 10 min under Xenon lamp irradiation, respectively. This result once again confirms the necessity of particle size reduction in the production of photocatalysts.</p>
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In this paper, we study the convergence for martingale sequences of random bounded operators. The condition for the existence of such a infinite product is established
In this study, we investigated the formation and influence of Ag particles on the physical properties and photocatalytic performance of Ag3PO4 photocatalysts when Ag particles adhered to the Ag3PO4 surface. The material is prepared by a simple precipitation method with illumination. The properties of the materials were investigated by X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), UV-vis absorption, and the photocatalytic ability to decompose organic solutions. The results show the vibrational change of the [PO4] group in the structure presented in the Raman scattering spectrum highest RhB decomposition. The experimental results indicated that the Ag\Ag3PO4 showed highly efficient and stable photocatalytic activity under visible light irradiation. The Ag\Ag3PO4 sample with the Ag+\PO43- the ratio of 3.6\1 gave efficiency when stimulated with visible light of Xenon lamps. This sample degraded almost completely to RhB in 10 ppm solution after 15 min of illumination, with a decomposition rate of 0.241 min-1.
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