Complete Photodegradation Research Articles

Exfoliated kaolinite nanolayers as an alternative photocatalyst with superb activity

In searching for alternative and abundant photocatalyst, exfoliated kaolinite nanolayers (nK) were prepared by a simple intercalation process. The effect of intercalating agents on the produced nK was studied by different instrumentations. XRD, FT-IR, and TEM confirm the exfoliation of kaolinite into nanolayers. Bandgap values were altered depending on intercalating agents as revealed by light absorption spectra. Photogenerated charge carriers observed through photoluminescence spectra. The produced nK applied for photodegradation of Rhodamine B dye (RhB) as an industrial model for wastewater treatment purposes. The results showed a complete photodegradation of RhB within a few minutes under UV with superb reaction kinetics. We refer the enhanced photocatalytic properties to the exposed metal oxide impurities on the surface of nK due to exfoliation. Performance tests revealed the reusability and stability of the prepared nK. This plentiful material is supposed to be a versatile alternative for the well-known photocatalysts with the possibility of large-scale production. Photodegradation mechanism of RhB is proposed.

Photodegradation of organic dyes by PAN/SiO2-TiO2-NH2 nanofiber membrane under visible light

This study proposed an effective method by using photocatalytic composite nanofiber membranes in order to degrade malachite green (MG) and acid red 27 (AR 27) to harmless products. The photocatalytic composite nanofiber membrane, Polyacrylonitrile (PAN) was incorporated with catalyst SiO2 and TiO2 photocatalyst. The PAN/SiO2-TiO2-NH2 nanofiber membrane was synthesized by electrospinning technique followed by chemical crosslinking. The results of SEM, EDX, FTIR and XRD confirmed the successful preparation of nanofiber membrane. XRD analysis shows the confirmation of SiO2 and TiO2 peaks. The result shows that PAN/SiO2-TiO2-NH2 nanofiber membrane exhibit the highest degradation with a good distribution of SiO2 and TiO2 on the PAN nanofiber membrane surface. The results showed that the complete photodegradation of MG and AR 27 with artificial visible-light was achieved after 9 and 25 min, respectively. In addition, the nanofiber membrane exhibited good stability and reusability for MG and AR 27 photodegradation and has potential to be applied in industrial application.

UV-Light Catalyzed Reduction of Cr(VI) by Graphene Oxide and its Significance for Cr(VI) Transformation in an Oxisol

Due to its unique properties, the potential application of graphene oxide (GO) in treating environmental pollution has attracted wide attention. In this study, the UV-light catalyzed photoreduction of Cr(VI) by GO was assessed as well as its adsorption toward Cr(VI), and FTIR and XPS techniques were adopted to reveal the underlying mechanisms. The surfaces of GO were negatively charged across the pH range examined. Therefore, the increase in pH resulted in the decrease in Cr(VI) adsorption due to the enhancement in repulsion between Cr(VI) and GO surfaces. The kinetic studies showed that the Cr(VI) adsorption proceeded quickly during the 0–24 h stage, followed by a slow process until to the end of reaction (96 h). Additionally, the kinetic data could be properly described with the pseudo-first-order rate equation (R2 = 0.9754). With the UV-light irradiation, Cr(VI) reduction in the presence of 0.5 g L−1 GO was observed with the concentration of Cr(VI) decreased from 0.1 mM to zero within 12 h at pH 3.0, while which would be suppressed as the pH increased. The addition of EDTA could enhance the photocatalytic Cr(VI) reduction due to the consumption of the photogenerated holes (h+), leaving more Cr(III) species present in solution. The generation of h+ was further confirmed by the complete photodegradation of 4-CP during 48 h. Moreover, the changes in FTIR and XPS spectrum of GO before and after reaction indicated the oxidization of epoxy and hydroxyl groups by holes or reduction by electrons was involved in the photoreaction. The photoreduction of Cr(VI) could was also observed in an oxisol with the existence of GO, with the disappearance of 0.1 mM of aqueous Cr(VI) at pH 4.40 after 36 h. The results above could enhance our understanding on the essence of photoreactivity of GO, and indicated that the potential release of GO into soil environments would be helpful to eliminate the risk posed by Cr(VI) through the UV-light irradiated photocatalytic reduction.

ZnS-containing industrial waste: Antibacterial activity and effects of thermal treatment temperature and atmosphere on photocatalytic activity

ZnS-containing industrial waste (ZnSW) from the mining-metallurgy industry was characterized as a useful photocatalytic material for environmental remediation. The XRD results reveal that the ZnSW contains cubic ZnS (sphalerite) as a major phase and hexagonal ZnS (wurtzite), triclinic FeS2 (pyrite) and hexagonal SiO2 (quartz) as minor phases. The antibacterial activity of the ZnSW was tested for four bacterial strains. The antibacterial activity against L. innocua under UV light irradiation is comparable to that observed with MRSA, whereas the inactivation rate against E. coli reaches 99% within 2 h of UV light irradiation. The ZnSW is found to be less effective in the inactivation of S. enteretidis. The impact of thermal treatment temperature (400–1000 °C) and atmosphere (in air and NH3) on photocatalytic activity of the ZnSW for photodegradation of gaseous acetaldehyde (AcH) and Bisphenol A (BPA) in aqueous solution under simulated solar light were investigated. The sample thermally treated at 500 °C in air completely mineralized AcH and BPA within 4 and 2 h of the photocatalytic reaction, respectively, due to the formation of a ZnSZnO heterojunction that promoted an effective charge separation. The sample thermally treated at 1000 °C in NH3 exhibited the highest photocatalytic efficiency in complete photodegradation of AcH and BPA within 3.5 and 1.5 h of the photocatalytic reaction, respectively, because of the introduction of nitrogen and formation of midgap defect states. The present study demonstrates the importance of the thermal treatment temperature and atmosphere for improving the photocatalytic activity of ZnS-containing industrial waste for environmental remediation.

Electrosynthesis of ZrO2 Nanoparticles with Enhanced Removal of Phenolic Compound

Abstract The electrogenerated zirconia (EGZrO2) catalyst was prepared via simple electrochemical method. The photoactivity of the catalyst was examined by photodegradation of phenol under varying pH, catalyst dosage, and initial concentrations. An amount of 0.40 g/L EGZrO2 was found to be the optimum dosage for 10 mg/L phenol, which gave almost complete photodegradation (98%) of phenol after 1 h under visible light irradiation at pH 9 and room temperature. These photoactivity were compared to commercial TiO2 and commercial ZrO2 which give approximately 80% and 78%, respectively. Photolysis was also conducted as control which resulted in 2% degradation. Therefore, in this study, it is believed that the electrochemical method system could improve the properties of EGZrO2 catalyst, and finally led to higher efficiency of its performance toward phenol degradation

Defect-assisted symmetric cleavage of naphthalene sulphonic acid group in azo dyes using β-In2S3 quantum dots as visible light photocatalyst

Naphthalene sulfonic acid, which is used in the synthesis of azo dye pigments, rubber processing chemicals and pharmaceuticals, is a carcinogenic substance that pollutes water bodies. In this work, we report on the visible light-driven symmetric cleavage of naphthalene sulfonic acid group, present in methyl orange dye and its conversion into the intermediate compounds. These compounds further degrade to inorganic ions such as carbon-di-oxide, nitrates, sulfates, water, and chlorine. Complete degradation of the dye, under visible light irradiation, is attained using β-In2S3 quantum dots as photocatalyst. During homogenous precipitation process, the β-In2S3 quantum dots (~ 9 nm) self-assemble to form microflowers (~ 50 nm) with high surface-to-volume ratio. These quantum dots exhibit size-dependent, active F2g, Eg and Ag1 Raman modes with peaks at ~ 150 cm−1 (In–In stretching mode), 219 cm−1 (In–S bending mode) and 300 cm−1, corresponding to the vibrational modes of cubic phase β-In2S3. The cubic phase β-In2S3 quantum dots are photoactive under visible light exposure and releases highly oxidizing OH· radicals. They have strong band-to-band emission in ultraviolet region (~ 380 nm) and exhibit broad band defect emission with maxima at blue (~ 484 nm), green (~ 580 nm) and red (~ 600 nm) region of electromagnetic spectrum. The emission intensity from these defect energy bands, which are due to sulfur vacancy, indium interstitials and oxygen incorporation, are tuned by varying the In-to-S ratio in the sample. These defects enhance their visible light absorption coefficient and assist in improving the photocatalytic efficiency of the cubic phase β-In2S3 quantum dots. Thus, defect-assisted complete (100%) photodegradation of the azo dye is achieved using cubic β-In2S3 quantum dots with low In-to-S ratio (1:1), low mass of 20 mg and minimum irradiation time (30 min). These photocatalysts can be reused 4 times under 30-min visible light irradiation. Cubic β-In2S3 quantum dots-microflowers is a highly efficient, ecofriendly photocatalyst, which even in very low concentration can remove toxicity from the dye-contaminated water, by exposure to direct sunlight for 30 min.

Recyclable MoO3 nanobelts for photocatalytic degradation of Rhodamine B by near infrared irradiation

AbstractMolybdenum trioxide (MoO3) represented an excellent photocatalytic performance with many applications, including degradation of organic contaminants and splitting of water. This paper presented a new route to synthesize MoO3 nanobelts with high aspect ratios and crystallinity by a hydrothermal technique. This work showed that the as‐synthesized nanobelts exhibited strong photocatalytic activity to degrade an organic dye of Rhodamine B (RhB) in aqueous solution under the exposure of the light source in the near infrared wavelength range, significantly improving the photocatalytic activity of the nanobelts. The results also showed that for a small concentration of RhB at 7.5 mg/L a complete photodegradation (for a given MoO3 nanobelts quantity of 0.1 g) can be reached after exposing for 60 min. For all concentrations of the RhB solution, the photodegradation exhibited an exponential dependence on the exposure time followed by a sudden shutdown, but no complete photodegradation can be reached. Also, the residual quantity of RhB in solution after the photocatalytic reaction was determined by the initial RhB concentration. The photocatalytic degradation can be interpreted by the pseudo–first‐order equation for the absorption of liquid/solid based on solid capacity; thus, photocatalytic degradation can be attributed to the interaction between the photoexcited electrons in the substrate and the antibonding orbital of the RhB in solution. The sudden shutdown was due to the inability of the photoexcited electrons in the substrate hopping to the antibonding orbital of RhB in the presence of the RhB intermediate products from the degraded RhB. In addition, this work showed that the photocatalytic reaction can be recovered after a thermal treatment of postreacted MoO3 nanobelts, enhancing the utilization efficiency of the catalysis.

Facile synthesis of Pt–In2O3/BiVO4 nanospheres with improved visible-light photocatalytic activity

We present a simple synthesis of BiVO4 nanospheres co-doped with Pt and In2O3 by a hydrothermal approach. The obtained samples exhibited monoclinic phase with homogeneously dispersed Pt and In2O3 on BiVO4 dopants as indicated by XRD, TEM, and XPS, respectively. The Pt–In2O3/BiVO4 photocatalyst exhibited highest surface area, lowest band gap, and much less charge recombination compared to pure, Pt or In2O3-doped BiVO4. The 1.2 gL–1 dose of Pt–In2O3/BiVO4 displayed a complete photodegradation of malachite green as an industrial model dye within 40 min with great reusability. A proposed mechanism is suggested based on the presented results.

Low Cost and Long Durability Material for Water Treatment: Titania-Coated Cement

Primary studies have been carried out on titanium dioxide powder, and revealed the efficient photocatalytic property of this material. More techniques have been developed to deposit the titanium dioxide particles onto a substrate, thus preserving from any further filtration after a water treatment. White cement has been used, as both a binder and a substrate, to deposit onto it titanium dioxide powder and to carry out the photodegradation of the tartrazine in an aqueous solution. The experiment has been conducted into a photocatalytic reactor designed and registered as a prototype patent. The complete photodegradation of the tartrazine molecule occurs with the same way as observed with the titanium dioxide powder in the aqueous solution of tartrazine. The same catalytic material of the titania-coated cement has been submitted for a series of the photocatalytic degradation tests of the tartrazine molecule and remained still active and comparable to those observed during the first reaction tests.

Functionalized magnetic nanoparticles: Synthesis, characterization, catalytic application and assessment of toxicity

Cost-effective water cleaning approaches using improved treatment technologies, for instance based on catalytic processes with high activity catalysts, are urgently needed. The aim of our study was to synthesize efficient Fenton-like photo-catalysts for rapid degradation of persistent organic micropollutants in aqueous medium. Iron-based nanomaterials were chemically synthesized through simple procedures by immobilization of either iron(II) oxalate (FeO) or iron(III) citrate (FeC) on magnetite (M) nanoparticles stabilized with polyethylene glycol (PEG). Various investigation techniques were performed in order to characterize the freshly prepared catalysts. By applying advanced oxidation processes, the effect of catalyst dosage, hydrogen peroxide concentration and UV-A light exposure were examined for Bisphenol A (BPA) conversion, at laboratory scale, in mild conditions. The obtained results revealed that BPA degradation was rapidly enhanced in the presence of low-concentration H2O2, as well as under UV-A light, and is highly dependent on the surface characteristics of the catalyst. Complete photo-degradation of BPA was achieved over the M/PEG/FeO catalyst in less than 15 minutes. Based on the catalytic performance, a hierarchy of the tested catalysts was established: M/PEG/FeO > M/PEG/FeC > M/PEG. The results of cytotoxicity assay using MCF-7 cells indicated that the aqueous samples after treatment are less cytotoxic.

Enhanced photoelectrochemical (PEC) and photocatalytic properties of visible-light reduced graphene-oxide/bismuth vanadate

A simple visible-light-assisted photocatalytic reduction of graphene oxide (GO) to reduced graphene oxide (rGO) using BiVO4 (BVO) in BVO/GO was designed to remarkably improve the photocatalytic degradation and photoelectrochemical (PEC) water splitting efficiencies of BVO. The resulting smaller particle size and strong interfacial interaction on the graphene sheet of the prepared BVO/rGO nanocomposite (NC) enhanced the photocatalytic degradation of tetracycline (TC) and methylene blue (MB) from aqueous solution, and also PEC water splitting. The photocatalytic degradation of MB and TC from aqueous solution using BVO/rGO was enhanced almost 2-fold compared to using BVO with complete photodegradation being achieved in 60 and 55 min of visible-light irradiation, respectively. The photocurrent onset potential of BVO/rGO was negatively shifted by −0.2 V vs. Ag/AgCl. The photocurrent density of BVO/rGO was greatly improved to 133 µA cm−2 at 0.8 V vs. Ag/AgCl, as compared to 21 µA cm−2 with BVO. The charge recombination time was greatly increased from 5 s−1 for BVO to 11 s−1 for BVO/rGO. The BVO/rGO photoanode exhibited long-term operation stability by maintaining 90.2% of the initial photocurrent density after 2400 s, while BVO showed poor stability of 65.1%. The great improvement of photocatalytic (2.0-fold) and PEC water splitting activity (6.3-fold) in BVO/rGO was attributed to the longer electron lifetime (2.2-fold), enhanced carrier concentration (5.87-fold), reduced interfacial electron transfer resistance, excellent stability and reusability, reduced particle size, and extended photoresponse range, which were derived from the ultimate coverage of BVO by rGO.

Coherent Bi2O3-TiO2 hetero-junction material through oriented growth as an efficient photo-catalyst for methyl orange degradation

In this work, we report the synthesis of a Bi2O3-TiO2 hetero-junction (HJ) material through a facile colloidal method. The hetero-junction formation follows a growth with a 145°Bi2O3/TiO2 crystal angle, owing to the large lattice mismatch between Bi2O3 and TiO2 crystals. With the Bi2O3-TiO2 hetero-junction material as a photocatalyst, methyl orange is degraded completely within two hours under common UV-lamp irradiation. The photo-catalyst remains highly-active for complete photo-degradation of methyl orange even after multiple experiments. The remarkable photo-catalytic properties are attributed to the remarkable mono-dispersivity of the colloidal Bi2O3-TiO2 nano-structure as well as the refined band structure with a valence band of 0.85 eV below that of TiO2 crystal.

Morphologically-dependent photocatalytic and gas sensing application of Dy-doped ZnO nanoparticles

Nowadays, growing populations and advanced industrialization has led to increase the problems related to water and air pollution. Herein, a rapid synthesis of Dy-doped ZnO nanoparticles is being reported through a facile and rapid solution combustion method. The synthesized nanoparticles were characterized by various techniques in term of their structural, morphological, optical, photocatalytic and gas sensing properties. The detailed characterization of the Dy doped ZnO nanoparticles confirmed the excellent crystallinity and optoelectronic properties. Herein, pure ZnO, different concentrations of Dy (2.0 at.wt%, 3.0 at.wt%, 4.0 at.wt%) were used as dopants (DZ1-DZ-3). It has been observed that the extent of Dy doping greatly influenced the morphological, structural, and band gap properties. The morphology of synthesized revealed its -leaf-shaped morphology high surface area to volume ratio and are well crystalline. Typical grain size of Dy-ZnO nanoparticles were found to be in the range of 47–77 nm. Further, the prepared Dy doped ZnO nanoparticles were used as photocatalyst for the photodegradation of DR-31 dye. Complete photodegradation of DR-31 dye was observed within 60 min of UV light irradiation. Kinetic studied reveals that all the Dy doped ZnO nanoparticle follow first order kinetics. The value of pseudo first order constant were found to be maximum 0.02925 (min)−1 for DZ-3. In order to develop smart and functional nanoscale sensor device for ethanol sensing, the prepared Dy doped ZnO nanoparticles were coated onto the surface of a glass substrate by spin coating technique. As fabricated sensors shows excellent sensing performance, even for a very low concentration of 25 ppm of ethanol, with the response in the range of 20–27%. Maximum sensitivity were found at an operating temperature of 150 °C. It is noteworthy that morphology of the nanoparticles of the sensitive layer is maintained after different concentration of Dy. Higher surface to volume ratio of the Dy doped ZnO nanoparticles were responsible for gas sensing and photocatalytic applications. The optimized concentration for DR-31 dye photodegradation and ethanol gas sensing applications were 4.0 at.wt% of Dy-ZnO nanoparticles.

Antimicrobial and antibiofilm efficacy of self-cleaning surfaces functionalized by TiO2 photocatalytic nanoparticles against Staphylococcus aureus and Pseudomonas putida

A photocatalytic sol of TiO2 nanoparticles has been used for creating self-cleaning antimicrobial flat and porous glass surfaces. The substrates were irradiated to study their photocatalytic properties and behavior in the presence of biofilm-forming bacteria. Smooth glass surfaces and glass microfiber filters were covered with 1.98×10−3±1.5×10−4gcm−2 and 8.55×10−3±3.0×10−4gcm−2 densities, respectively. Self-cleaning properties were analyzed using the methylene blue 365nm UV-A photodegradation test. TiO2-coated filters achieved rapid and complete photodegradation of methylene blue because of the better TiO2 dispersion with respect to the glass slides. The effect of functionalized surfaces on the growth and viability of bacteria was studied using the strains Staphylococcus aureus and Pseudomonas putida. After irradiation (2h, 11.2Wm−2, 290–400nm), the initially hydrophobic surface turned hydrophilic. The antibacterial effect led to extensive membrane damage and significant production of intracellular reactive oxygen species in all TiO2-loaded irradiated specimens. The reduction of cell viability was over 99.9% (>3-log) for TiO2 on glass surfaces. However, the polymeric extracellular matrix formed before the irradiation treatment was not removed. This study highlights the importance of bacterial colonization during dark periods and the difficulty of removing the structure of biofilms.

Ag nanoparticle immobilized mesoporous TiO2-cobalt ferrite nanocatalyst: A highly active, versatile, magnetically separable and reusable catalyst

Here, a simple method for preparation of a novel nanocatalyst, composed of Ag nanoparticle, mesoporous TiO2 and CoFe2O4 nanoparticle, has been reported for three important reactions (i) epoxidation of styrene, (ii) reduction of 4-nitrophenol (4-NP) and (iii) photocatalytic degradation of Methylene Blue dye. The synthesized catalyst exhibited high catalytic activities towards all of these three reactions. For styrene epoxidation, ∼98.1% conversion of styrene with ∼94.5% selectivity of styrene oxide was observed within 10h. This catalyst catalyzed the reduction of 4-nitrophenol within 4min with kapp=1.08min−1. The catalyst also showed complete photodegradation of Methylene Blue within 60min under visible light exposure. The catalyst was easily recovered from the reaction mixture by applying a permanent magnet externally. The recovered catalyst also showed excellent reusability. Easy synthesis methodology, versatile catalytic activity, easy separation and good reusability make this nanocatalyst attractive in the field of heterogeneous catalysis.

A Facile Method Synthesis of {100}-Truncated Rhombic Dodecahedral Cu2O Microcrystals and Its Photocatalytic Activity

In this study, we report a facile solution-based one-step reduction method to synthesis of {100}-truncated rhombic dodecahedral Cu2O crystals. Each {100}-truncated rhombic dodecahedral Cu2O has six square {100} faces in addition to twelve {110} facets. The obtained microstructures were characterized by SEM, TEM, HRTEM, XRD and UV-vis spectrum. The adsorption and photocatalytic activity of as-prepared {100}-truncated rhombic dodecahedral Cu2O polyhedral for decomposition of methylene blue were investigated and compared to that of octahedral. It is found that the {100}-truncated rhombic dodecahedron Cu2O have a much better photocatalytic activity than octahedron. The{100}-truncated rhombic dodecahedra exposing the {110} facets exhibit an exceptionally good photocatalytic activity toward the fast and complete photo degradation of methylene blue due to a high number density of surface copper atoms, demonstrating the importance of their successful preparation.

Solar Photocatalytic Degradation of Methylene Blue by ZnO Nanoparticles.

The scalable and economical synthesis approach of ZnO has always been demanded, since it is very useful material in the degradation of hazardous dyes. Herein, a scalable synthesis approach for ZnO nanoparticles by precipitating the precursors such as zinc sulphate heptahydrate and ammonium hydroxide has been proposed. Calcinations at suitable temperatures can improve crystalline nature of materials. Therefore as-synthesized ZnO nanoparticles were calcinated at different temperatures 400 °C, 650 °C, 900 °C, 1150 °C, and subsequently their physical and morphological properties were characterized. The TEM analysis revealed the morphology, whereas XRD and SAED confirmed the purity and crystalline nature of ZnO. Moreover, photo catalytic degradation/adsorption results for methylene blue dye of lower (2.5 ppm) and higher concentrations (5 ppm) in the presence and absence of sunlight and ZnO nanoparticles are also reported. Addition of ZnO nanoparticles to methylene blue resulted in enhanced rate of photo degradation in the presence of sunlight. The complete photodegradation of 2.5 and 5 ppm methylene blue in sunlight occurred in 90 min and 165 min, respectively in presence of ZnO nanoparticles. In general many photocatalytic degradation studies had been reported using an artificial light source; however in the present work direct sunlight has been utilized.

Characterization and photocatalytic properties of TiO$_{2}$/chitosan nanocomposites synthesized by hydrothermal process

Nanocomposites of TiO$_{2}$/chitosan (nTC) were synthesized by hydrothermal process at 200 $^{\circ}$C. Photocatalytic activity of the nanocomposites was studied with degradation of malachite green (MG) in aqueous medium. Structural and physico-chemical properties of the obtained nanocomposites were characterized by XRD, SEM, BET, FTIR, and particle size analyzer. Complete photodegradation of MG was successfully achieved with the aid of the nanocomposites. The optimum photocatalytic degradation conditions, irradiation time, irradiation power, and amount of catalyst were studied. Photocatalytic activity of the synthesized nanocomposites in terms of degradation of MG was compared with that of undoped TiO$_{2}$ (synthesized by our team) and chitosan under normal conditions. It was concluded that the synthesized nanocomposites had better photocatalytic activity. The best result (100{\%} degradation) was obtained with amount of nTC of 0.25 g and irradiation time of 120 min.

Interfacial effect of the nanostructured Ag2S/Co3O4 and its catalytic mechanism for the dye photodegradation under visible light

In this study, the synthesis of a highly hybrid, heterogeneously structured nanocomposite catalyst consisting of Ag2S nanoparticles dotted on a Co3O4 microrod array is reported. The average diameter and length of the Co3O4 microrods was optimized to be approximately 300nm and 20μm, respectively, and the average size of the Ag2S nanoparticles was approximately 10nm. When the Ag2S nanoparticles were deposited on the Co3O4 microrods, the characteristic optical band gap energy of Co3O4 decreased from 1.26eV to 1.23eV, and the intensity of the absorbance peak at 650nm increased significantly. The catalytic activity of nanosized Ag2S/Co3O4 for the photodegradation of organic contaminants with potassium hydrogen persulfate (PMS) or ozone (O3) was evaluated using basic green 1 dye (BG1) as a model pollutant. In the presence of the hybrid Ag2S/Co3O4 catalyst developed in this study, the complete photodegradation of the BG1 solution was achieved in 20min and 6min when PMS and O3 were used, respectively. In addition, the experimental results suggest that the catalytic photodegradation of BG1 using the Ag2S/Co3O4/PMS and Ag2S/Co3O4/O3 processes was dominated by the OH and O2− radicals, respectively.

Plasmonic enhanced photocatalytic activity of semiconductors for the degradation of organic pollutants under visible light

Metal oxide semiconductors hold great promise for applications in energy conversion and storage, environmental remediation, and other areas. However, critical factors such as the high rate of charge–carrier recombination and limited light absorption have restricted more practical and viable applications. In this context, plasmonic nanostructures of noble metals in combination with semiconductors offer a promising future for the next generation of energy needs. In this work we investigate the coupling between Plasmonic gold nanostructures and catalyst supports such as TiO2, ZnO and Al2O3 in order to study the photocatalytic degradation of Bisphenol A (BPA) under visible irradiation (laser source and LED). The experimental investigations have shown extremely fast and complete photodegradation of organic pollutants in water. The influence of laser power and photocatalyst band gap on the catalytic activity was investigated as well. Au/TiO2 catalyst showed the fastest degradation of BPA due to efficient electron transfer from excited noble metal gold nanoparticles to the semiconductor.