Photocatalytic Decomposition Of Organic Pollutants Research Articles

Morphology and photocatalytic tetracycline degradation of g-C3N4 optimized by the coal gangue

Coal gangue (CG), a solid waste from coal mining and processing, has raised concerns about its environmental impact. Graphitic carbon nitride (g-C3N4) is promising for photocatalytic decomposition of organic pollutants, but its performance is hampered by its inherent defects. In this study, the compound of coal gangue and g-C3N4 was formed by in-situ loading g-C3N4 on the surface of coal gangue. After recombination, the morphology of g-C3N4 changes from block structure to tremella nanosheet. This change not only increases the specific surface area of g-C3N4, but also broadens the light absorption spectrum of g-C3N4. Compared with original g-C3N4, the photocurrent of the complex in visible light is increased twice, and the tetracycline (TC) degradation rate is 2.1 times faster. The structure, optical properties, band structure, morphology and charge transfer mechanism of the composite were analyzed by a series of characterization techniques. It is found that coal gangue can promote the space charge transfer and separation of g-C3N4, and the cyclic test compound has good activity stability. In this paper, a strategy of comprehensive utilization of coal gangue is proposed, which can not only reduce the environmental risk of coal gangue, but also provide carbon nitride (CN) based photocatalytic materials with superior photocatalytic properties.

Comparison of Electro-Fenton and Photoelectro-Fenton for removal of Acrylonitrile Butadiene Styrene (ABS) from petrochemical wastewater

The purpose of this study was the evaluation the Electro-Fenton (EF) and Photo Elecro-Fennton (PEF) efficiencies to remove of some pollution indicators from effluents of Acrylonitrile Butadiene Styrene (ABS) petrochemical industries affected by the operational parameters such as operation time, pH, current density, and concentration of H2O2. The EF and PEF reactors were made and a batch study was performed to optimize the operational parameters. The optimum operating conditions were determined as pH 5, reaction time 60 min, H2O2 concentration 50 mmol/lit and current density 20 mA/cm2 for EF process and pH 5, operation time 30 min, H2O2 concentration 25 mmol/lit, current density of 20 mA/cm2 for PEF process. The highest removal efficiencies of COD (chemical oxygen demand), turbidity, total kejaldahl nitrogen (TKN) and total suspended solids (TSS) by EF and PEF processes under optimal conditions were obtained 86.7, 88.1, 67.9 and 64.1% for EF and 92.4, 93.7, 70.5 and 67.2% for PEF process, respectively. The PEF process resulted in higher removal efficiencies than that of the EF process to remove COD and TKN especially. Also, the amount of energy consumption for EF and PEF were obtained 10.1 and 9.3 kW h/m3, respectively. The PEF process was more capable to remove the pollutants from wastewater, than the EF process in a shorter time and with a lower H2O2 concentration due to the presence of UV radiation, which causes the photocatalytic decomposition of organic pollutants.

Rose-inspired 3D 1T-MoS x /Ti3C2T x /TiO2 photocatalyst for water purification

The rose-inspired photocatalyst, 1T-MoS x /Ti3C2T x /TiO2, demonstrated exceptional activity in the simultaneous removal of hexavalent chromium (Cr(VI)) and methylene blue (MB), achieving high efficiencies of 97.7% and 97.2% respectively. Furthermore, it exhibited effective degradation of another dye, Rhodamine B (Rh.B). Scanning electron microscopy figures showed its unique nanoflower morphology. The introduction of titanium carbide nanosheets (Ti3C2T x ) and the formation of Schottky junctions can effectively prolong the carrier lifetime. The degradation path of MB was deduced by liquid chromatography–mass spectrometry, which confirmed the process of photocatalytic decomposition of organic pollutants. Compared to physical purification methods, it offers the advantage of not only removing pollutants but also degrading them. Furthermore, by utilizing MB as a sacrificial agent, the reduction can take place in a mild neutral environment, resulting in minimized secondary pollution. Through its distinctive three-dimensional structure and the Ti3C2T x cocatalyst, the 1T-MoS x /Ti3C2T x /TiO2 photocatalyst demonstrates remarkable catalytic activity, and effective purification of wastewater containing Cr(VI) and organic dyes.

Synchronized surface oxygen states and electron-hole passage in microwave-assisted tungsten oxide for photocatalytic organic decomposition and antibacterial activity

The present study focuses on controlling the composition of microwave-fabricated tungsten oxide (WO3) nanoparticles through annealing at 500 °C. The significance of annealing on the surface oxygen states and the photocatalytic performance of WO3 nanoparticles were systematically investigated for the removal of organic pollutants and bacteria. The optimum photocatalyst, microwave-assisted WO3 which was successively annealed for 6 h and Pt-loaded (Pt/WO3-M-6 h) demonstrated high photocatalytic performances in inactivation (99 %) against E. coli and S. aureus as well as in degradations of Orange II dye (93 %) and BPA (99 %) under one sun illumination for 180 min. The integration of WO3-M-6 having a moderate amount of surface oxygen defects and Pt loading could provide the most favorable environment in charge transfer by reducing the electron-hole recombination and as an electron collector, respectively. Detailed mechanisms have been proposed for the photocatalytic decomposition of organic pollutants and the photocatalytic disinfection of waterborne bacteria.

Interfacial Nucleation Mechanism of Water-Soluble Ag-In-S Quantum Dots at Room Temperature and Their Visible Light Catalytic Performance.

A novel interfacial reaction nucleation mechanism for the preparation of water-soluble Ag-In-S quantum dots (AIS QDs) was proposed in which interfacial acid regulates the concentration of hydroxide ions outside the complex and sulfur sources attack cations at the interface of the complex, covalent bonds between cations and sulfur sources are formed at the interface of the complex, and the nucleation and growth of crystals is finished at room temperature. By bypassing the heating process normally necessary for crystal nucleation and growth, AIS QDs can be produced on a large scale under simple, mild conditions. At the same time, the characteristics of this mechanism enable AIS QDs to be directly synthesized in an organic pollutant solution. This study represents a significant advance in the mechanism of crystal synthesis and contributes to the photocatalytic decomposition of organic pollutants from theory to practice.

A comparative study of 0D and 1D Ce-ZnO nanocatalysts in photocatalytic decomposition of organic pollutants

Nanosized zinc oxide is an intriguing material that can be applied in various fields. In this study, Ce doped ZnO nano-catalysts (Ce-ZnO) were synthesized by two different methods (i.e., hydrothermal (Ce-ZnO-HT) and polymer gel combustion (Ce-ZnO-CB) methods) to compare their photodegradation efficiency. The prepared material characteristics were investigated using XRD, SEM, TEM, FTIR, UV-Vis, PL, XPS, EDS, and BET. The bandgap of both nanoparticles (NPs) was 2.95 eV, despite the fact that the morphology of Ce-ZnO-HT NPs was 1D-rod-shaped and that of Ce-ZnO-CB NPs was 0D-spherical. However, the surface area and oxygen vacancy rate of Ce-ZnO-HT NPs were higher than those of Ce-ZnO-CB NPs. These differences are directly related to the photocatalytic activity of Ce-ZnO NPs. Accordingly, the results showed that photocatalytic efficiency was classified in the order Ce-ZnO-HT > Ce-ZnO-CB > pure ZnO, and the photocatalytic reaction rate constant of Ce-ZnO-HT used to decompose MB was 3.0 times higher than that of Ce-ZnO-CB. Interestingly, the photodegradation mechanism study revealed that hydroxyl radicals and holes were shown to be more important contributors to methyl blue degradation than photo-induced electrons and superoxide radical ions.

Carbon-based TiO2-x heterostructure nanocomposites for enhanced photocatalytic degradation of dye molecules

Application of brown titanium dioxide (TiO2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO2-x nanoparticles with g-C3N4, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO2-x nanocomposite with high rate constants of 0.075 min−1, 0.083 min−1 and 0.093 min−1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e−)/hole (h+) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO2-x is carried out.

The Effect of Noble-Metal Deposition Routes on the Characteristics and Photocatalytic Activity of M-TiBi1.9%O2 (M = Pt and Pd)

The effect of deposited noble-metals and their deposition routes on the photocatalytic decomposition of organic pollutants over M-TiBi1.9%O2 (M = Pt and Pd) under visible-light irradiation have been investigated. Glycol-assisted UV photodeposition and impregnation-reduction deposition routes (NaBH4 or combined He/H2) have been applied to prepare 1%M-TiBi1.9%O2 samples. The results show that the photocatalytic activity of 1%M/TiBi1.9%O2 via glycol-assisted UV pretreatment (1%M-365UV) is quite similar to those obtained after combined He/H2 pretreatment (1%M-He/H2), much superior to that of 1%M-NaBH4. A mild reduction process via glycol-assisted UV irradiation for 1%M-TiBi1.9%O2 shows impressive advantages over high temperature He/H2 reduction. The photocatalytic performance enhancement is attributed to the efficient capability of small Pt nanoparticles (NPs) for facilitating charge separation and providing active sites. It is hoped that this work could guide a facile synthesis of deposited noble-metal with small size toward achieving a highly-active supported noble-metal catalyst for diverse catalytic applications.

R-GO supported g-C3N4 /NiMgAl layered triple hydroxide hybrid as a Visible Light photocatalyst for organic dye removal

A reduced graphene oxide supported g-C3N4/NiMgAl layered triple hydroxide (LTH) hybrid novel photocatalyst was synthesized by hydrothermal process, and its photocatalytic degradation activity was assessed against the methylene blue (MB) dye. The obtained experimental outcomes show that the as-prepared LTH are anchored on the surfaces of negatively charged g-C3N4 and r-GO nanosheets. The dye degradation capacity of as-prepared samples was examined under visible-light irradiation and the r-GO supported g-C3N4/LTH hybrid formation shows significantly improved visible-light-driven photocatalytic activity along with good reusability. The electrochemical performances of as-prepared samples were investigated by cyclic voltammetry (CV), Nyquist plots and photocurrent measurement by three-electrode based system. As compared to other samples the r-GO/g-C3N4/LTH hybrid photocatalyst shows better electrochemical and photocatalytic activity. The improved catalytic performance may be due to the synergistic effect among the photocatalyst and high charge-carrier separation efficiency. The r-GO acted an agent to enhance the charge carrier separation in heterojunction, which consequently enhanced the photocatalytic activity. The current effort could open a new way for the preparation of visible-light-driven LTH based nanomaterials for effectual photocatalytic decomposition of organic pollutants.

Enhanced the photoelectrocatalytic performance of TiO2 nanotube arrays by the synergistic sensitization of Ag-AgBr nanospheres.

Ag-AgBr nanospheres were synthesized on the tubular surface of TiO2 nanotube arrays (TiO2 NTA/Ag-AgBr) by the one-pot hydrothermal deposition strategy using cetyltrimethyl ammonium bromide (CTAB) as bromine source and morphology controlling agent. The results showed that the TiO2 NTA/Ag-AgBr (0.025) prepared with 0.025 g CTAB had the uniform particle distribution, high visible light absorption, photoelectric conversion activity and photoelectrocatalytic (PEC) removal of organic dyes and heavy metal ions. The high photocatalytic decomposition of organic pollutants in waste water was attributed to the synergistic effect of Ag-AgBr nanospheres with the strong visible light response and effective separation of electron-hole pairs. The active group and photocatalytic mechanism for the rapid pollutant removal were systematically explored. This work will open the window of TiO2 NTA based photoelectrodes for the applications in solar energy conversion and dyeing waste water purification.

Selectively Photocatalytic Activity of an Open-Framework Chalcogenide Built from Corner-Sharing T4 Supertetrahedral Clusters.

The photocatalysis process with high selectivity is a very important research forefront for the semiconductor photocatalytic decomposition of organic pollutants. However, the rational design of efficient photocatalysts with high selectivity is still a challenge. Here, we present an open-framework chalcogenide (Heta)8[In14Sn2Zn4Se33] (Heta = ethanolamine-H+) (compound 1) constructed from T4 supertetrahedral clusters [In14Sn2Zn4Se35]12- with visible-light-driven selectively photocatalytic degradation activity. Single-crystal XRD analysis shows that compound 1 crystallizes in I41/acd (no. 142) space group, with a = b = 24.3462(2) Å, c = 45.0062(9) Å, V = 26676.9(7) Å3, and Z = 8. Under visible-light irradiation, the selectively photocatalytic activities of 1 were evaluated by photodegradation of two kinds of cationic dye molecules, i.e., methylene blue (MB) and rhodamine B (RhB), against two anionic dyes, methyl orange (MO) and Kermes red (KR), with different sizes. We show that the adsorption capability and charge-matching between organic dyes and the supertetrahedral cluster together with a suitable band structure make it an excellent and selective photocatalyst. This is the first example of an open-framework chalcogenide based on supertetrahedral T4 for the selectively semiconductor photocatalytic decomposition of organic dyes.

Multifunctional and recyclable TiO2 hybrid sponges for efficient sorption, detection, and photocatalytic decomposition of organic pollutants

Developing techniques for monitoring and removing organic pollutants such as solvents and dyes in environmental media is a very important task nowadays. To get rid of the pollutants, efficient materials that can sorb, detect, and decompose such compounds have been consistently sought after. Herein, we demonstrate a simple and inexpensive method to fabricate eco-friendly multifunctional and recyclable TiO2 hybrid sponges composed of a polydimethylsiloxane (PDMS) network and functional nanoparticles. Water-soluble crystals were used to construct porous templates and TiO2 nanoparticles were additionally integrated into the templates where liquid PDMS was filled. After curing the PDMS, the TiO2 integrated hybrid sponges were finally obtained by dissolving the templates with water. By using the fabricated hybrid sponges, sorbed organic pollutants were qualitatively detected via molecular-specific Raman signals. Furthermore, we showed the recyclability by achieving photocatalytic decomposition of the sorbed pollutants induced by the TiO2 nanoparticles. These results are instructive for further applications and also contribute toward solving problems relating to environmental pollution.

Roles of Vanadium and Nitrogen in Photocatalytic Activity of VN-Codoped TiO2 Photocatalyst.

In the present manuscript, we explore the VN-codoped TiO2 system intended to understand the role played by each dopant in synergistic enhancement in performance of TiO2 photocatalyst. The photocatalytic decomposition of organic pollutants in aqueous solution under visible light was used as a probe reaction to evaluate the performance of VN-codoped TiO2 samples with different V and N concentrations. An optical measurement of VN-codoped TiO2 shows considerable improved visible light absorption with increase in V-concentration as compared to increase in N concentration, which was due to the effective narrowing of the band gap by V-doping. The energy levels formed by N-dopants act as the trapping centers for photogenerated holes to suppress recombination process as indicated by PL and TRPL results. It is also observed that at high V-concentrations recombination centers are created in the form of oxygen vacancies as indicated by XPS and PL. In VN-codoped TiO2 , addition of N partially fills these oxygen vacancies to reduce the number of recombination centers and prolong the lifetime of charge carriers. Thus, V improves the visible light absorption while N reduces the recombination of electron-hole pairs, thus creating the synergistic effect to produce three times better performance than pure TiO2 .

Novel indirect Z-scheme photocatalyst of Ag nanoparticles and polymer polypyrrole co-modified BiOBr for photocatalytic decomposition of organic pollutants

Mimicking the natural photosynthesis, artificial Z-scheme photocatalysis enables more efficient utilization of solar energy for degradation of organic pollutants. Herein, an indirect Z-scheme photocatalyst of Ag nanoparticles and polymer polypyrrole (PPy) co-modified BiOBr was rationally designed and successfully synthesized via a combination of hydrothermal technique, in-situ photo-reduction and oxidative polymerization method. Dramatically, BiOBr-Ag-PPy system showed superior photocatalytic performance and excellent stability in degradation of both the typical triphenylmethane dye (malachite green) and colorless organic compound (phenol). Especially for BAP-0.4, its degradation conversion of malachite green was 6.4, 2.4 and 1.6 times of those of pure BiOBr, BiOBr-Ag and BiOBr-PPy, respectively, and can still maintain more than 91% even after fifth cycle experiment. The trapping experiments of reactive species and electron spin resonance (ESR) tests confirmed that the O2− and h+ were main active species in photocatalytic degradation. Through experimental investigations and theoretical analyses, the possible charge carriers transfer process over BiOBr-Ag-PPy ternary Z-scheme photocatalyst was proposed. In the indirect all-solid-state Z-scheme BiOBr-Ag-PPy heterojunction structure, by quenching the photo-generated electrons and holes with weaker redox ability in metal Ag nanoparticles, the electrons in the lowest unoccupied molecular orbital (LUMO) of PPy and holes in the valence band (VB) of BiOBr can survive and then have the opportunity to participate in the surface reaction, thus showing an increased photocatalytic activity.

Fabrication and photoactivity of ionic liquid-TiO2 structures for efficient visible-light-induced photocatalytic decomposition of organic pollutants in aqueous phase.

To investigate the effect of the ionic liquid (IL) chain length on the surface properties and photoactivity of TiO2, a series of TiO2 microspheres have been synthesized via a solvothermal method assisted by 1-methyl-3-octadecylimidazolium chloride ([ODMIM][Cl]) and 1-methyl-3-tetradecylimidazolium chloride ([TDMIM][Cl]). All as-prepared samples were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), scanning transmission microscopy (STEM) and the Brunauer–Emmett–Teller (BET) surface area method, whereas the photocatalytic activity was evaluated by the degradation of phenol in aqueous solution under visible light irradiation (λ > 420 nm). The highest photoefficiency (four times higher than pristine TiO2) was observed for the TiO2 sample obtained in the presence of [TDMIM][Cl] for a IL to TiO2 precursor molar ratio of 1:3. It was revealed that interactions between the ions of the ionic liquid and the surface of the growing titanium dioxide spheres results in a red-shift of absorption edge for the IL–TiO2 semiconductors. In this regard, the direct increase of the photoactivity of IL–TiO2 in comparison to pristine TiO2 was observed. The active species trapping experiments indicated that O2•− is the main active species, created at the surface of the IL–TiO2 material under visible-light illumination, and is responsible for the effective phenol degradation.

Enhanced performance of direct Z-scheme CuS-WO3 system towards photocatalytic decomposition of organic pollutants under visible light

CuS-WO3 composites were synthesized by an in situ solution method at low temperature. The crystalline phase, morphology, particle size, and the optical properties of CuS-WO3 samples were characterized by XRD, SEM, XPS, and UV–vis diffuse reflectance spectra. CuS-WO3 composites showed much higher activity for photocatalytic degradation of RhB as compared with WO3 and CuS. The degradation rate constant over 1wt% CuS-WO3 catalyst was 4.4 times and 9.2 times higher than that of WO3 and CuS, respectively. It is found that holes (h+) and superoxide radical anions (O2−) are the dominant reactive species by using methanol, disodium ethylenediaminetetraacetate (EDTA) and ascorbic acid as scavengers. Band structure analysis shows that bottom of CB of WO3 is very similar with and higher (ca. 0.01eV) than the top of VB of CuS. The results of PL showed that the similarity renders the recombination between photogenerated holes on the VB of CuS and photogenerated electrons on the CB of WO3 possible and easy, forming a direct Z-scheme in CuS-WO3. This result in that more electrons in the CB of CuS and holes in the VB of WO3 survived, and then participated in the photocatalytic degradation of RhB, showing an increased activity.

Internally/Externally Bubble-Propelled Photocatalytic Tubular Nanomotors for Efficient Water Cleaning.

We describe a highly effective bubble-propelled nanomotor for the photocatalytic decomposition of organic pollutants in water. Two different tubular TiO2 nanomotor systems are presented: one with Pt nanoparticles decorated on the inner surface and the other with Pt nanoparticles decorated on the outer surface. This is the first time that we have observed the autonomous movement of a tubular nanomotor without the aid of any surfactant, as well as a tubular nanomotor externally decorated with Pt propelled by oxygen bubbles. The synergy between the Pt nanoparticles and the superhydrophilic wetting behavior of the TiO2 nanotubes endows the two nanomotor systems with high speed at very low H2O2 fuel concentrations without the addition of any surfactant. The efficient photodecomposition of rhodamine B demonstrates the intermixing and photocatalytic ability of the two nanomotor systems, which opens new avenues for the development of multifunctional bubble-propelled micro/nanomotors with myriad practical applications.

Photocatalyst of organic pollutants decomposition: TiO2/glass fiber cloth composites

Herein TiO2 coated on glass fiber cloth (TiO2/glass fiber cloth, TGFC) was synthesised by sol-gel method. We demonstrated the property about TGFC of photocatalytic decomposition of organic pollutants under ultraviolet-visible (UV–vis) light and sunlight. Glass fiber cloth (GFC) was chosen as the support of TiO2 in order to improve the practical applications for water purification. TGFC-1–6 were characterized by ERSEM, XRD and XPS. Photocatalytic decomposition of crystal violet (CV) was carried out to investigate the photocatalytic activity of TGFC. The efficiency of TGFC-3 was the best. And its photocatalytic decomposition rate of the second to fifth cycle was higher than the first cycle. The photocatalytic decomposition rate of TGFC-3 was 85% under sunlight from 8:00–14:00. We could design and regulate the shape of TGFC and estimate the area, weight and thickness of TiO2, more easily than glass fibers. TGFC is suitable for photocatalytic decomposition of organic pollutants in the water, especially to be fixed in sewage treatment pool and reused.

Facile synthesis of hierarchical Cu2O nanocubes as visible light photocatalysts

Hierarchically structured Cu2O nanocubes have been synthesized by a facile and cost-effective one-pot, solution phase process. Self-assembly of 5nm Cu2O nanocrystallites induced through reduction by glucose affords a mesoporous 375nm cubic architecture with superior visible light photocatalytic performance in both methylene blue dye degradation and hydrogen production from water than conventional non-porous analogues. Hierarchical nanocubes offer improved accessible surface active sites and optical/electronic properties, which act in concert to confer 200–300% rate-enhancements for the photocatalytic decomposition of organic pollutants and solar fuels.

Visible Light Driven Decomposition of Organic Compounds By Two Different Cocatalysts

1. Introduction Photocatalytic decomposition of organic pollutants is one of the promising method for environmental purification. Most of the researchers focused on efficient decomposition of environmental organic contaminants under visible light irradiation or indoor fluorescent light.1 Oxide-supported metal catalysts are widely acknowledged as important catalysts that are related to versatile key in photochromism, chemical sensing and photocatalytic activity. Tungsten trioxide (WO3) acts as a ideal visible light photocatalyst owing to its small band gap energy (2.4-2.8 eV) and high oxidation power of vanlence band holes. But, WO3 exhibits low photocatalytic activity due its high recombination rate of photoexcited electrons and holes. In order to suppress the recombination of photoexcited carriers and significantly increase the photocatalytic efficiency, most research has focused to prepare WO3 doping constituent or WO3 composites.2,3 In the present study, we have synthesized PtPb/WO3 and PtAu/WO3 alloy catalysts, demonstrated to exhibit the efficiency for the decompostion of organic pollutants under visible light irradiation. 2. Experimental A simple one-pot synthesis approach to obtain WO3 supported PtAu catalyst is as follows. In the synthesis, 0.5 g of WO3was suspended in 15 mL of anhyrous methanol for 15 min in a two neck round bottom flask. Pt (0.0075 g) and Au (0.0045 g) precursors were dissolved in 15 mL anhydrous methanol in the shielded vial uder Ar atmosphere and transferred to the suspensions. Then, the solution was stirred for 30 min to yield homogeneous color soluion. Required amount of NaBH4 in mehtanol was injected into the suspensions. The product were washed and centrifuged with anhydrous methanol for three times and dried under vacuum. Similar procedure was followed to synthesis the PtPb/WO3 catalyst. 3. Results and Discussion Figure 1 shows the TEM images of (a) Pt/WO3 (b) PtPb/WO3 and (c) PtAu/WO3 photocatalysts. Pt and PtPb and PtAu NPs are showed monodispersity and homogeneity on the WO3 supports. The average particle size of the three catalysts can be ranked as PtPb/WO3~PtAu/WO3 > Pt/WO3. The TEM results show that the addition of Pb and Au increases the size of NPs. Figure 2 depicts that the CO2 formation profile over different photocatalysts under visible light irradiation time. PtPb/WO3 photocatalyst (1 wt %) shows the higher rate of CO2formation over other photocatalysts. The details about the characterization and photocatalytic activity of catalysts would be discussed in the presentation. 4.