Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Morphology-dependent photocatalytic H2-production activity of CdS

Abstract: Various morphologies of CdS photocatalysts, including nanoparticles, nanorods, urchin-like shape and nanowires were prepared via a solvothermal process by tailoring the solvent. Based on both experimental and theoretical simulation investigation, the microstructure evolution mechanism was specified. Visible-light-driven photocatalytic activities for hydrogen production over the different CdS products were compared and rationalized. CdS nanowires prepared with the utilization of tetraethylenepentamine (TEPA) as solvent and l -cysteine as sulfur precursor displayed excellent photocatalytic H2-production activity of 803 μmol h−1 with quantum efficiency (QE) of 37.7% at 420 nm. The enhanced photocatalytic activity was ascribed to the high purity, good crystallinity, and unique microstructure and band structure, which was favorable for transfer of photogenerated carriers and thus reduced the recombination of electron–hole pairs. This work showed that the nature of solvent had significant influence on the photocatalytic H2-production activity of CdS, which adds knowledge on designing photocatalysts for visible-light-driven photocatalytic hydrogen evolution.

Visible light-assisted heterogeneous Fenton with ZnFe2O4 for the degradation of Orange II in water

Abstract: In this study, a visible (Vis) light response photocatalyst was synthesized via a simple reduction–oxidation method. The structure, morphology and optical properties of the catalyst were well characterized. The absorption capability of ZnFe 2 O 4 in visible-light region was demonstrated by the high rate of Orange II decolorization under Vis/ZnFe 2 O 4 /H 2 O 2 process. Guided by studies to explore the effects of radical scavengers and to quantify the yield of hydroxyl radical ( OH) production, OH on the surface of the catalyst was found to be the dominating reactive species for the Orange II removal. Moreover, ZnFe 2 O 4 maintained high activity, crystallinity and extremely low iron and zinc leaching during repeated experiments. The intermediate products were identified by GC–MS and a possible pathway is accordingly proposed to elucidate the mechanism of Orange II degradation by OH. In addition, high extent of mineralization was obtained as the chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies were 86.6% and 60.4%, respectively, within 60 min reaction. The toxicity tests with activated sludge indicated that the toxicity of the solution increased during the first 30 min but then decreased significantly as the oxidation proceeded.

Atomic scale g-C3N4/Bi2WO6 2D/2D heterojunction with enhanced photocatalytic degradation of ibuprofen under visible light irradiation

Abstract: Although photocatalytic degradation is an ideal strategy for cleaning environmental pollution, it remains challenging to construct a highly efficient photocatalytic system by steering the charge flow in a precise manner. In this study, a novel atomic scale g-C3N4/Bi2WO6 heterojunction (UTCB) constructed by ultrathin g-C3N4 nanosheets (ug-CN) and monolayer Bi2WO6 nanosheets (m-BWO) was successfully prepared by hydrothermal reaction. The UTCB heterojunctions were characterized by various techniques including XRD, TEM, AFM, BET measurements, UV–vis spectrometry, and XPS. The results indicated that UTCB heterojunctions were assembly of m-BWO on ug-CN and presented high separation efficiency of photogenerated carriers. Under visible light irradiation, the optimum molar ratio of ug-CN/m-BWO (1:4, UTCB-25) reached almost 96.1% removal efficiency of IBF within 1 h, which was about 2.7 times as that of pure m-BWO. The photocatalytic mechanisms of UTCB-25 were revealed, suggesting that the synergistic effect of UTCB-25 heterojunction with strong interfacial interaction promoted the photoinduced charge separation. According to the LC–MS/MS, five photodegradation pathways of IBF under visible light irradiation were proposed. This study could open new opportunities for the rational design and a better understanding of atomic scale two dimensions/two dimensions (2D/2D) heterojunctions in environmental or other applications.

Photochemical and photocatalytic degradation of an azo dye in aqueous solution by UV irradiation

Abstract: The photochemical and photocatalytic degradation of aqueous solutions of Solophenyl Green (SG) BLE 155%, an azo dye preparation very persistent in heavy colored textile waters, has been investigated by means of ultraviolet (UV) irradiation. The pure photochemical process demonstrated to be very efficient for low initial concentrations of the dyestuff. For higher concentrations the photocatalyitic degradation was carried on using commercial titanium dioxide, and mixtures of this semiconductor with different activated carbons (AC) suspended in the solution. The kinetics of photocatalytic dyestuff degradation were found to follow a first-order rate law. It was observed that the presence of the activated carbon enhanced the photoefficiency of the titanium dioxide catalyst. Differently activated carbon materials induced different increases in the apparent first-order rate constant of the process. The effect was quantified in terms of a synergy factor (R) already described in the literature. The kinetic behavior could be described in terms of a modified Langmuir–Hinshelwood model. The values of the adsorption equilibrium constants for the organic molecules, KC, and for the reaction rate constants, kC, were 0.0923 l mg−1 and 1.58 mg l−1 min−1 for the TiO2/UV process and 0.0928 l mg−1 and 2.64 mg l−1 min−1 for the TiO2+AC/UV system with highest synergy factor, respectively. The mechanism of degradation was discussed in terms of the titanium dioxide photosensitization by the activated carbon.