Photocatalytic Activity For Phenol Degradation Research Articles

NaOH and temperature-induced formation of Bi-based BixOyBrz photocatalyst for phenol degradation

In this work, Bi-based BixOyBrz photocatalyst including BiOBr, Bi2O3/Bi4O5Br2, BiOBr/Bi4O5Br2 and Bi4O5Br2 were successfully prepared by adding NaOH and controlling reaction temperature. BiOBr/Bi4O5Br2 composite displayed excellent photocatalytic activity for phenol degradation compared with other Bi-based BixOyBrz photocatalyst. Toxicity experiments suggested that low environmental toxicity of BiOBr/Bi4O5Br2 composite for the growth state of Sudangrass seeds and Mung bean seeds. A BiOBr/Bi4O5Br2 S-scheme heterojunction was proposed to explain the photocatalytic degradation mechanism.

Enhancing Photocatalytic Degradation via the Synergetic Effect of Vacancies and Built-In Potential in a BiOCl/BiVO4 p-n Heterojunction.

Photoinduced charge separation and surface reactions are essential for ensuring high quantum efficiency of the photochemical and photophysical processes. BiVO4-based heterojunctions are promising materials for high-performance photocatalysts; however, their photocatalytic performance is significantly lower than the theoretical limit due to the sluggish water oxidation dynamics and rapid recombination of charge carriers on the catalyst surface. To address these issues, oxygen vacancies (OVs) are introduced to a rationally designed BiVO4-based heterojunction using built-in potential and gradient OVs to promote the separation of carriers and increase the photocatalytic activity. The heterojunctions with OVs exhibit a 2-fold increase in the photocatalytic activity for phenol degradation compared with that of pristine BiVO4. Additionally, density functional theory is applied to elucidate the synergistic mechanism of light absorption and charge separation in BiOCl/BiVO4 p-n heterojunction photocatalysts containing vacancies. The obtained results demonstrate a synergistic effect of vacancies and the built-in potential, providing a pathway for defect engineering in photocatalytic processes.

Reactive seeding growth of cobalt-doped MIL-88B(Fe) on Al2O3 membrane for phenol removal in a photocatalytic membrane reactor

In this study, cobalt-doped MIL-88B(Fe) (xCoMIL-88B(Fe)) was successfully synthesized and grown on an Al2O3 support. The cobalt doping of MIL-88(Fe) not only enhanced its visible-light absorption but also improved free electron–hole pair separation. On adding peroxymonosulfate (PMS), 5CoMIL-88B(Fe) powder demonstrated superior photocatalytic phenol removal than that without the PMS or catalyst. The reactive seeding growth of cobalt-doped MIL-88B(Fe) was employed to prepare a 5CoMIL-88B(Fe) membrane coupled with a filtration module to produce a photocatalytic membrane reactor (PMR). The permeate flux of the photocatalytic membrane reactor (PMR) was approximately 2900–4000 L m−2 h−1 bar−1 (LMH), which demonstrated over 90% phenol removal efficiency and exhibited high stability, reusability, recyclability, and high photocatalytic activity for phenol degradation over 10 cycles utilizing 5CoMIL-88B(Fe)@Al2O3 membrane with PMS. This is the first study to demonstrate a cobalt-doped MIL-88B(Fe) membrane through the reactive seeding method for a PMR system, which is an effective and sustainable process for wastewater treatment.

Synthesis of Bi2S3-TiO2 nanocomposite and its electrochemical and enhanced photocatalytic properties for phenol degradation

Bi2S3-TiO2 nanocomposite with improved visible light photocatalytic activity for phenol degradation was the main focus of the current investigation, which involved solvothermal synthesis. FE-SEM, XRD, and TEM analyses of the Bi2S3-TiO2 nanostructure illustrated the successful synthesis of the Bi2S3-TiO2 nanocomposite. According to electrochemical experiments, the Bi2S3-TiO2 nanocomposite had a low recombination rate toward the TiO2 nanorods and Bi2S3 nanoparticles and a quicker interfacial charge transfer. According to the results of optical analyses, the bandgap energies of TiO2 nanorods, Bi2S3 nanoparticles, and Bi2S3-TiO2 nanocomposite were determined to be 3.15 eV, 1.32 eV, and 2.55 eV, respectively. The results of photocatalytic degradation analyses revealed that TiO2 nanorods, Bi2S3 nanoparticles, and Bi2S3-TiO2 nanocomposite all successfully treated 250 mL of a 50 mg/L phenol solution after being exposed to visible light for 125, 230, and 95 min, respectively. This indicates that the Bi2S3-TiO2 nanocomposite had a rapid rate of photocatalytic degradation because of the synergistic effect of Bi Results of the investigation on the application of Bi2S3-TiO2 nanocomposite for phenol degradation in real-world samples showed that it was capable of treating phenol in industrial wastewater effectively through photocatalytic degradation.

Construction of magnetically recoverable MnZnFe2O4@Ag3PO4 Z-scheme photocatalyst for rapid visible-light-driven phenol degradation.

Visible-light-driven magnetic heterojunction as a promising photocatalysts has received much attention in environmental remediation. In this work, novel Z-scheme heterojunction MnZnFe2O4@Ag3PO4 (MZFO@APO) magnetic photocatalysts with excellent visible-light-driven photocatalytic activity are successfully constructed and characterized. The photocatalytic activity for phenol degradation is measured, and photodegradation mechanism is investigated with EPR, radical trapping experiments, and LC-MS. It turns out that the heterojunction introduced MZFO exhibits good adsorption effect on visible light and the direct Z-scheme bandgap alignment of MZFO and APO significantly improves charge separation and electron transfer, outperforming that of pure APO. MZFO@APO-40% with 40% APO content shows the rapid photodegradation performance, obtaining a 100% removal efficiency of phenol (25mg L-1) after 12-min visible light irradiation, and its kinetic constants are approximately 25.3 and 4.9 times higher than that of P25 TiO2 and pure APO, respectively. Especially, MZFO@APO-40% also possesses a high magnetic separation property and can be efficiently reused for 5 cycles. Additionally, EPR and radical trapping experiments confirm that h+, O2-, and 1O2 are the main active species in the photocatalytic process. Hydroquinone and small molecular organic acids such as maleic acid and oxalic acid are detected by LC-MS, which further indicates that the pathway of phenol degradation involves hydroxylation, open-ring reactions, and mineralization reactions. The novel addition of MZFO in photocatalyst construction has the potential to promote its application in environmental remediation.

Enhancing the Photocatalytic Activity of TiO2/Na2Ti6O13 Composites by Gold for the Photodegradation of Phenol

This study aims to synthesize Au/TiO2/Na2Ti6O13 composites to reduce the occurrence of recombination and increase photocatalytic activity in phenol degradation. Gold was used due to its high stability and strong surface plasmon resonance (SPR) properties which make it operate effectively in the visible light spectrum. The prepared composites were characterized using XRD, SEM, TEM, FTIR, and DRS. The results showed that the composite consisted of rutile TiO2 with a crystal size of 38–40 nm and Na2Ti6O13 with a crystal size of 25 nm. The gold in the composite has a crystallite size of 16–19 nm along with the percentage of gold added. Morphological analysis shows that the composite has the form of inhomogeneous spherical particles with gold spread among composites with sizes less than 20 nm. FTIR analysis showed the presence of Na–O and Ti–O–Ti bonds in the composite. The best composite was 3% Au/TiO2/Na2Ti6O13 which had high crystallinity, small particle size, and bandgap energy of 2.59 eV. Furthermore, it had an efficiency 205% better than without gold. After that, cost estimation is proposed as a large-scale application. This study describes the total cost, break-even analysis, and payback analysis for the commercialization needs of the designed photocatalytic catalyst.

How Do Ionic Liquids Affect the Surface Structure of Titania Photocatalyst? An Electron-Trap Distribution-Analysis Study

Titanium(IV) oxide, titania, photocatalyst particles were prepared from titanium alkoxide in the presence of several kinds of ionic liquids, and it was clarified that a group of samples exhibited photocatalytic activity for phenol degradation under the irradiation of light of wavelength >400 nm higher than those of the other group of samples. Although the conventional structural analytical results could not be related to the activity, electron-trap distribution measured by reversed double-beam photoacoustic spectroscopy suggested that a part of the ionic liquid induced the creation of a surface amorphous layer covered with hydrophobic organic residues to enhance the adsorption of phenol on the surface.

A novel microwave-assisted strategy to fabricate multifunctional photoactive titania-based heterostructures with enhanced activity

TiO2-ZnO heterostructures with multifunctional photoactive properties were prepared using the two-stage microwave method. The presence of a binary crystalline system (anatase – wurtzite) was confirmed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The multifunctional character of the obtained photoactive materials was evaluated in two different processes – photocatalysis and photovoltaics. Photo-oxidation tests proved that the TiO2-ZnO heterostructures demonstrate high photocatalytic activity in phenol degradation. Furthermore, the prepared titania-based heterojunction systems were employed as precursors of the semiconducting layers in the DSSCs working electrodes. The photovoltaic parameters of the cells, assembled with electrodes post-treated with TiCl4 solution, have been tremendously improved by as much as forty-fold. Additionally, the scientific novelty of the work should be emphasized, resulting from the utilization of microwave-assisted synthetic strategy for the first time to prepare highly efficient photoactive materials with significant application potential in both photocatalysis and photovoltaics (DSSC cells).

Enhanced Photocatalytic Degradation of Phenol Using Urchin-Like ZnO Microrod-Reduced Graphene Oxide Composite under Visible-Light Irradiation

In this study, visible-light-driven ZnO microrod-rGO heterojunction composites were successfully synthesized via a facile and scalable hydrothermal process. The prepared photocatalyst heterojunction was examined using different techniques including XRD, SEM, FTIR, UV-Vis spectroscopy, and TGA to reveal their crystal phase, morphology, and other optical properties. The photocatalytic performance of the obtained ZnO-rGO composites was measured by the photodegradation of phenol under visible light illumination. The addition of graphene over the catalyst exhibited an enhanced photocatalytic activity for phenol degradation due to its high surface area and decreasing rate of electron-hole separation. Kinetic studies proved that the degradation of phenol process happened by following the pseudo-first-order kinetic model. The effective conditions for degradation of phenol using ZnO-rGO composite were 0.2 g L-1catalyst dose, pH -4, and initial concentration 20 ppm of phenol solution. Comparing with ZnO microrods, the heterojunction composite degraded the organic pollutants of phenol solution up to 84.2% of efficiency displaying the highest photocatalytic activity, whereas urchin-like ZnO catalyst exhibited much less photocatalytic activity for phenol degradation under visible light irradiation. This result envisages immense properties, showing a great potential industrial application for the removal of phenolic wastewater.

Thermal annealing of ordered TiO2 nanotube arrays with water vapor-assisted crystallization under a continuous gas flow for superior photocatalytic performance

Ordered titanium dioxide nanotube arrays fabricated via electrochemical route are considered as a promising material for photocatalytic applications. Due to their amorphous character, a subsequent crystallization step is usually required. In this work, well-aligned nanotube arrays were annealed under flowing gas streams of different compositions (air/steam, air, N2/steam, N2, and O2/steam) in a temperature range from 140 to 543 °C. Under continuous gas flow, the morphology of the crystallized titanium dioxide is strongly affected by the gas atmosphere. When using a dry gas for annealing, the tube structure was almost destroyed after 1 h treatment at 473 °C. In contrast, when annealing the titania nanotube array in a water vapor/gas stream, the tube morphology can be maintained up to 543 °C and 10 h annealing time. Moreover, nanotube arrays crystallized in a flowing gas atmosphere containing water vapor showed a significantly higher photocatalytic activity for phenol degradation under UV irradiation than nanotube arrays crystallized in a dry gas stream. Reasons for this behavior might be the preservation of the tubular structure as well as a lower concentration or density of structural defects in presence of water vapor which leads to an enhanced generation of reactive oxygen species when the arrays are exposed to UV-light.

Hydrothermal Synthesis and Crystal Structure of a Novel Bismuth Oxide: (K0.2Sr0.8)(Na0.01Ca0.25Bi0.74)O3.

A novel distorted perovskite-type (K0.2Sr0.8)(Na0.01Ca0.25Bi0.74)O3 was prepared by a hydrothermal method using the starting materials NaBiO3·nH2O, Sr(OH)2·8H2O, Ca(OH)2, and KOH. Single-crystal X-ray diffraction of the novel compound revealed a GdFeO3-related structure belonging to the monoclinic system of the space group Cc with the following cell parameters: a = 11.8927 (17) Å, b = 11.8962 (15) Å, c = 8.4002 (10) Å, and β = 90.116 (9)°. The final R-factors were obtained as R1 = 0.0354 and wR2 = 0.0880 (using all the data). K+ and Sr2+ ions were distributed at four types of A-sites. On the other hand, four Bi5+-sites (Bi1, Bi2, Bi3, and Bi4) were occupied by four Ca2+ ions (Ca1, Ca2, Ca3, and Ca4), and the first three B-sites were occupied predominantly by Bi5+ with Na+ ions. The forth B-site was occupied predominantly by the Ca2+ ion with Bi5+ ions. Two types of B-sites, thus forming tilted distorted (Na/Ca/Bi)O6 and (Bi/Ca)O6 octahedra, have an ordering of 3:1 represented as (K/Sr)4(Na/Ca/Bi)3(Bi/Ca)O12. The distorted (Na/Ca/Bi)O6 and (Ca/Bi)O6 octahedra formed a perovskite-type network by corner sharing with features closely matching those of a GdFeO3-type structure. The novel compound is the first example of a perovskite-type bismuth oxide containing only Bi5+ in a system without a Ba atom and has a unique ordering (3:1) of the B site. The compound showed photocatalytic activity for phenol degradation under visible light irradiation.

Optimized Synthesis Temperature and Time to Obtain Crystalline Carbon Nitride with Enhanced Photocatalytic Activity for Phenol Degradation

In this work, the crystalline carbon nitride photocatalysts were synthesized by an ionothermal technique with varied synthesis temperature of 500, 550, and 600 °C, and synthesis time of 2, 4, and 6 h. Fourier transform infrared spectra showed the successful formation of the prepared carbon nitrides from their characteristic vibration peaks. X-ray diffraction patterns suggested that the same phase of poly(triazine imide) and heptazine could be observed, but with different crystallinity. The optical properties showed that different temperatures and synthesis time resulted in the different band gap energy (2.72–3.02 eV) as well as the specific surface area (24–73 m2 g–1). The transmission electron microscopy image revealed that the crystalline carbon nitride has a near-hexagonal prismatic crystallite size of about 50 nm. Analysis by high-performance liquid chromatography showed that the best photocatalytic activity for phenol degradation under solar light simulator was obtained on the crystalline carbon nitride prepared at the 550 °C for 4 h, which would be due to the high crystallinity, suitable low band gap energy (2.82 eV), and large specific surface area (73 m2 g–1). Controlling both the temperature and synthesis time is shown to be important to obtain the best physicochemical properties leading to high activity.

Hydrothermal Synthesis and Crystal Structure of a Mixed-Valence Bismuthate, Na3Bi3O8.

Four types of bismuth oxides, Na3Bi3O8, NaBiO3, α-Bi2O3, and ε-Bi2O3, were obtained by hydrothermal reactions using NaBiO3·nH2O in NaOH solution. The crystal structure of a new phase (Na3 Bi3+)Bi25+O8 ((Na0.75Bi0.25)2BiO4) was determined by using single crystal X-ray diffraction data, and this compound was found to show a Na2MnCl4-related structure with a monoclinic system (space group, Pm) with the following lattice parameters: a = 5.990 (2) Å, b = 3.335 (2) Å, c = 10.108 (2) Å, and β = 91.08 (3)°. The final R-factors R1 and wR2 were 0.041 and 0.090 (all data), respectively. The new phase was composed of mixed valence states of Bi (Bi3+ and Bi5+, with a mean Bi valence of 4.30) with five distinct Bi sites, where two Bi5+ (Bi1 and Bi2) fully occupied the distorted octahedral sites and three Bi3+ (Bi3, Bi4, and Bi5) were statistically distributed at the split sites with Na+ (Na3, Na4, and Na5). The Na6 site is fully occupied. The distorted Bi5+O6 octahedra formed one-dimensional chains via edge-sharing along the b-axis, with the chains held by Bi3+/Na+ split sites. The structural feature except for the split distribution of Bi3+/Na+ was classified as a Na2MnCl4-type structure. DFT calculations based on a model discounting the split distribution of Bi3+/Na+ indicated that Bi 6s and O 2p orbitals form sp hybridization at the conduction band. This new mixed valence bismuth oxide exhibited photocatalytic activity for phenol degradation under visible light irradiation. In addition to Na3Bi3O8, the hydrothermal reaction using NaBiO3·nH2O in NaOH solution yielded micrometer-sized single crystals of an ilmenite-type NaBiO3 and two polymorphs of bismuth oxides with monoclinic (α-Bi2O3) and orthorhombic (ε-Bi2O3) structures, depending on the reaction temperature and NaOH concentration.

Photocatalytic Degradation of Phenol in Aqueous Solutions Using TiO2/SiO2 Composite

Photocatalytic degradation of phenol in aqueous solutions was investigated using TiO2/SiO2 composites with different Ti/Si molar ratios (95/5(75/25) and calcined at 500 (C. The synthesized composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms. Their photocatalytic activities for phenol degradation were evaluated in a batch reactor under simulated visible light using a special 26 W compact lamp. The results showed that all synthesized composites consist of pure anatase phase with high crystallinity and exhibit high photocatalytic activities for phenol degradation. At the initial concentration 10 ppm phenol and catalyst dose 0.10 g/L, the highest photocatalytic activity for phenol degradation was observed with the synthesized TS05 composite (Ti/Si molar ratio of 95/5), resulting in 53.5 % phenol degradation yield after 4 h. The corresponding phenol degradation yields using the synthesized composites TS15 (Ti/Si molar ratio of 85/15) was ~ 40.0 % and TS25 ((Ti/Si molar ratio of 75/25) was ~ 36.0 %. The TS05 composite could be a promising photocatalyst for the removal and degradation of organic pollutants.

Hydrothermal synthesis and crystal structure of a fluorite-type Pb0.35Bi0.65O1.59 compound with photocatalytic activity

A fluorite-type compound, Pb0.35Bi0.65O1.59, was synthesized by a hydrothermal reaction. The crystal structure of the compound was refined using synchrotron powder X-ray diffraction data; the cubic cell dimensions were a = 5.4864 (1) Å and the space group was Fm3-m (No. 225). The final R-factors were Rwp = 5.76% and Rp = 4.36%. The band gap of this compound was estimated to be 0.98 eV from the UV–vis spectrum. This compound comprised mixed-valence states Bi3+ and Bi5+ with an average Bi valence of 3.83. This compound exhibited photocatalytic activity for phenol degradation and was thermally stable up to 380 °C.

Fabrication of visible-light-active Bi/BiOI-Bi2O3 composite with enhanced photocatalytic activity

Plasmonic Bi0 modified BiOI-Bi2O3 composite (Bi/BiOI-Bi2O3) was prepared via in situ UV reduction method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) techniques were carried out to identify the formation of semimetal Bi0. The results indicated that the dot-like bismuth particles were originated from the partial reduction of lattice Bi3+ to Bi0 by accumulated conduction band electrons in BiOI-Bi2O3. The as-prepared ternary composite exhibited enhanced visible-light-response, decreased charge transfer impedance and higher charge carrier density relative to unmodified BiOI-Bi2O3. Due to synergistic effect between plasmonic Bi0 and BiOI-Bi2O3 heterojunction, dramatically enhanced photocatalytic activity for phenol degradation can be achieved. After 3.5 h visible light irradiation, the value for phenol removal efficiency was ca. 60% and 100% on BiOI-Bi2O3 and Bi/BiOI-Bi2O3, respectively. The calculated zero-order rate constant on Bi/BiOI-Bi2O3 was 1.7 and 3.9 times that on BiOI-Bi2O3 and Bi2O3, respectively. In addition to phenol, organic dyes (zwitterionic RhB, cationic MB and anionic Org II) were also used as model pollutants. Pronounced photocatalytic degradation by Bi/BiOI-Bi2O3 can be observed, further confirming the importance of Bi0. Trapping experiments using different scavengers indicated that photogenerated holes were major active species during the degradation of phenol. Furthermore, good stability was also observed in 5 successive cyclic runs. This study opens a new strategy for in situ preparation of plasmonic Bi0 modified composite.

Novel Photocatalytic Nanocomposite Made of Polymeric Carbon Nitride and Metal Oxide Nanoparticles.

Semiconducting polymers are promising materials for photocatalysis, batteries, fuel applications, etc. One of the most useful photocatalysts is polymeric carbon nitride (PCN), which is usually produced during melamine condensation. In this work, a novel method of obtaining a PCN nanocomposite, in which PCN forms an amorphous layer coating on oxide nanoparticles, is presented. Microwave hydrothermal synthesis (MHS) was used to synthesize a homogeneous mixture of nanoparticles consisting of 80 wt.% AlOOH and 20 wt.% of ZrO2. The nanopowders were mechanically milled with melamine, and the mixture was annealed in the temperature range of 400–600 °C with rapid heating and cooling. The above procedure lowers PCN formation to 400 °C. The following nanocomposite properties were investigated: band gap, specific surface area, particle size, morphology, phase composition, chemical composition, and photocatalytic activity. The specific surface of the PCN nanocomposite was as high as 70 m2/g, and the optical band gap was 3 eV. High photocatalytic activity in phenol degradation was observed. The proposed simple method, as well as the low-cost preparation procedure, permits the exploitation of PCN as a polymer semiconductor photocatalytic material.

Photocatalytic degradation of phenol by LaFeO3 nanocrystalline synthesized by gel combustion method via citric acid route

Focusing on the photocatalytic degradation of phenol under visible light, the synthesized lanthanum orthoferrites (LaFeO3) by gel combustion method using citric acid as sacrificial agent were investigated. With the highest reaction temperature of 200 °C, the physicochemical properties of synthesized samples were characterized by X-Ray diffraction (XRD) analysis, Brunauer–Emmet–Teller (BET), and Energy Dispersive X-Ray spectroscopy (EDS). On the other hand, UV–Vis spectroscopy analysis was carried out to determine the phenol photodegradation activities and mechanism. The results suggested the well-defined LaFeO3 nanocrystals with specific area of 28 m2 g−1 were successfully synthesized. Besides that, variations in operating parameters such as pH, catalyst dosage and initial concentration of phenol in synthetic wastewater were also examined. In conclusion, LaFeO3 nanocrystalline exhibited an exceptional photocatalytic activity for phenol degradation, thus providing a perfect alternative for pharmaceutical wastewater treatment.

Mesoporous pyrophyllite–titania nanocomposites: synthesis and activity in phenol photocatalytic degradation

Pyrophyllite–TiO2 nanocomposite PTi750 was successfully synthesized using a sol–gel method at ambient temperature based on exfoliation of the pyrophyllite layered clay by incorporation of the TiO2 precursor titanium(IV) t-butoxide. PTi750 exhibited higher photocatalytic activity in phenol degradation compared with commercial TiO2 Aeroxide P25. Ag-photodeposited PTi750 was more photoactive than PTi750, exhibiting detoxification, total degradation, and good mineralization of polluted solution and excellent stability after five reuses at optimal conditions in terms of the parameters pH, H2O2 concentration, and photocatalyst amount. The nanocomposites were investigated using several techniques, viz. diffuse-reflectance ultraviolet–visible (UV–Vis) spectrophotometry, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, X-ray fluorescence spectroscopy, Fourier-transform infrared spectroscopy, and Brunauer–Emmett–Teller (BET) specific surface area measurements.

Titanium dioxide and cadmium sulfide co-sensitized graphitic carbon nitride nanosheets composite photocatalysts with superior performance in phenol degradation under visible-light irradiation

In this work, TiO2-CdS-gCNNSs heterojunction photocatalysts were successfully synthesized. CdS was deposited on the surface of gCNNSs via electrostatic attraction; TiOC, TiOCO and TiON bonds were produced in TiO2-CdS-gCNNSs, strengthening the interaction between TiO2 and gCNNSs. The TiO2-CdS-gCNNSs photocatalyst showed excellent photocatalytic activity for phenol degradation under visible-light irradiation, which was higher than that of CdS-gCNNSs, CdS-TiO2 and TiO2-gCNNSs. The improved photocatalytic performance of TiO2-CdS-gCNNSs was ascribed to more adsorption sites, enhanced light harvesting ability and effective separation rate of electron-hole pairs. Furthermore, the results of photocatalytic mechanism indicated that h+ and O2− played a more significant role on the phenol degradation.