Ag3PO4 Photocatalyst Research Articles

Enhanced band gap energy of one-pot mechano-synthesized Ag3PO4 for Orange G photodegradation under visible light irradiation: An in-depth experimental and DFT studies

The present study highlights the efficiency of Ag3PO4 photocatalyst with a band gap of 2.25 eV, synthesized by a green and one-pot simple mechanochemical method, towards photodegradation of orange G under visible irradiation. The phase structure, morphology, and optical properties of mechano-synthesized Ag3PO4 were investigated using X-ray diffraction, Scanning Electron Microscopy, Thermogravimetric Analysis, Fourier Transform Infrared, the Brunauer-Emmet-Teller surface area, and UV–vis diffuse reflectance spectroscopy. DFT calculations were also conducted for band gap energy prediction. The photocatalytic activity of the sample was evaluated using a central composite design for surface response methodology (CCD-RSM) to determine the optimal conditions for Orange G (OG) removal. The photocatalytic activity of Ag3PO4 was approximately 93 % within 20 min of reaction under irradiation for 24.6 mg/L and 11 mg/L of Ag3PO4 and Orange G, respectively. Trapping experiments confirmed that peroxides and hydroxyl radicals are the dominant active species in the photodegradation process.

Simple precipitation synthesis and solar light-driven photocatalytic degradation of Ag3PO4 floating photocatalysts

Abstract A highly efficient and stable photocatalyst, Ag3PO4, was prepared using a simple co-precipitation method at room temperature. The precursors used in this process were AgNO3 and K2HPO4. The resulting Ag3PO4 photocatalyst forms irregularly-shaped spheres with diameters ranging from 300 to 1 μm. The shape of the Ag3PO4 photocatalyst slightly changes when different surfactants (PVA, PVP, PEG) are used. The powdered Ag3PO4 photocatalyst exhibits excellent visible light-driven photocatalytic performance. It is capable of decomposing rhodamine B (RhB) as a model pollutant in just 5 min under visible light irradiation. This performance is quite remarkable. Interestingly, Ag3PO4 floating composite sheets have been achieved using polystyrene (PS) and fumed silica Aerosil 200. After three cycles, the decolorization of RhB dyes remains at 87% with the 30% Ag3PO4@PS/Aerosil 200 sheet. This indicates that the Ag3PO4@PS/Aerosil 200 photocatalyst is highly reusable and stable.

Synthesis and application of Ag3PO4 photocatalyst modified by g-C3N4 for tetracycline hydrochloride degradation

Finding highly efficient photocatalysts has practical significance for antibiotics degradation. In this work, g-C3N4 modified Ag3PO4 had been prepared via in-situ deposition method. Their photocatalytic activities were investigated through tetracycline hydrochloride (TCH) degradation under visible light. In summary, sample 6 wt% g-C3N4/Ag3PO4 (6 wt% CN/APO) exhibited a good degradation efficiency (72.1 %) to TCH within 30 min, while pure Ag3PO4 and g-C3N4 was only 57.4 % and 5.8 %, respectively. Because of the construction of heterojunction structure, 6 wt% CN/APO composite had low fluorescence intensity, high photocurrent density and low resistance, which were helpful for the rapid separation of photogenerated carriers. Therefore, the photocatalytic property of Ag3PO4 was obviously enhanced. In addition, sample 6 wt% CN/APO also showed excellent photocatalytic stability, and h+ played a main role in TCH degradation. Its possible photocatalytic mechanism was also elucidated.

What's behind their various activities? Discerning the importance of surface terminations in Ag3PO4 semiconductor from DFT calculations

The surface energy and band gap of inorganic semiconductors are essential properties for a wide variety of applications in materials science, and studying morphologies holds significant importance. However, it is challenging to find a correlation between them at the atomic scale when these materials are multifunctional. This motivates the development of predictive computational models that can optimize these materials based on these quantities. Present findings shed light on the structure and electronic properties of (100), (110), and (111) surfaces of Ag3PO4 by using density functional theory calculations. By introducing two concepts, namely, polyhedron energy and polyhedron band gap, we provide compelling evidence for the effects of surface termination of Ag3PO4 photocatalyst. We compare our predictions to experimental crystal habits, and our results not only allow us to explain their evolution for obtaining a given morphology but also offer a coherent explanation, based on atomic-scale insights, for the discrepancies of morphology-photocatalytic activity relationship of Ag3PO4 in the recent literature. Overall, this work opens a novel avenue for first-principles calculations of morphology and provides a roadmap for the design of more effective inorganic semiconductors with desirable physicochemical properties for potential applications.

A Co-doped Ag3PO4 photocatalyst: Efficient degradation of organic pollutants and enhancement mechanism

In this study, an efficient Co-doped Ag3PO4 photocatalyst was prepared by the deposition method. Compared with Ag3PO4, the degradation efficiency of the optimal sample CAP-2 (the mole ratio of Co/Ag was 0.057 %) for MO (20 mgL−1) increased from 53.4 % to 95.0 % within 20 min, and the degradation efficiency for phenol (20 mgL−1) increased from 57.9 % to 91.8 % within 80 min. Moreover, the CAP-2 sample performed excellent mineralization ability and stable recycling capacity. Free radical capture experiments and electron spin resonance (ESR) measurements indicated that holes (h+) and superoxide radicals (⋅O2−) were the main active radicals. Doping Co ions broadened the optical absorption, introduced impurity level to promote the separation of carriers, and generated additional ⋅O2− owing to the mutual conversion of Co3+ and Co2+, thus considerably improving Ag3PO4 photocatalytic performance. This work provides a new reference for doping metal ions modified semiconductor photocatalysts to efficiently degrade organic pollutants.

Silver phosphate–bacterial cellulose nanocomposites as visible light photocatalyst for wastewater purification

Silver phosphate (Ag3PO4) nanoparticles were deposited on bacterial cellulose (BC) nanofibrils as an eco-friendly, efficient, and reusable visible light active photocatalyst. BC–Ag3PO4 nanocomposites (BCAgP) with different BC/Ag3PO4 weight ratios were prepared by solution-precipitation method. The nanocomposites were characterized by UV-Visible diffuse reflection spectroscopy, XRD, FTIR, BET, and FESEM. Highly crystalline Ag3PO4 nanoparticles were well entrapped inside nano fibrillated BC matrix and eventually deposited along the fibers. Photocatalytic activity of the BCAgP nanocomposites were investigated by dye degradation experiments under solar light. The composite with BC: Ag3PO4 weight ratio of 1:4 (BCAgP14) showed the highest photocatalytic efficiency compared to other weight ratios and pure Ag3PO4. The sample also shows good photocatalytic activity even after 4 runs indicating its photostability. Higher photocatalytic efficiency of BCAgP14 nanocomposite was explained due to optimum Ag3PO4 loading and higher visible light absorption capacity. Bacterial cellulose is supposed to improve the photocatalytic activity of silver phosphate by promoting the adsorption of dyes and extending the charge recombination time under visible light of Ag3PO4 photocatalyst.

Thin silica shell on Ag3PO4 nanoparticles augments stability and photocatalytic reusability.

Semiconductor photocatalysts are promising cost-effective materials for degrading hazardous organic contaminants in water. Ag3PO4 is an efficient visible-light photocatalyst for the oxidation of water and dye degradation. The excited Ag3PO4 photocatalyst uses a hole to oxidise water or organic contaminants except the electron, which reduces Ag+ to Ag0. In the present study, the inherited disadvantage was overcome by a thin silica shell overcoating on Ag3PO4 nanoparticles. The silica-coated Ag3PO4 nanoparticles retain the photocatalytic activity even after five cycles of photodegradation, while the bare Ag3PO4 nanoparticles show a photocatalytic activity declined to half. The study demonstrates that the thin silica shell enhances the photostability, keeping the photocatalytic activity unaffected, even after several cycles of photodegradation of dyes. XPS analysis showed that the Ag0 formation on the surface of bare Ag3PO4 is greater than that on silica-coated Ag3PO4, which declines the photocatalytic activity of Ag3PO4 after five cycles of photodegradation. Electrochemical studies identified that the intermediates, such as OH˙ and O2-, formed during water oxidation play a crucial role in the photodegradation of dyes. This study can provide insights into the design of core-shell semiconductor nanostructures for reusable photocatalytic applications.

Tuning the particle size, physical properties, and photocatalytic activity of Ag3PO4 materials by changing the Ag+/ ratio

This study demonstrates the influence of the Ag+/ ratio in precursor solution on the crystal structural formation, morphology, physical properties, and photocatalytic performance of a Ag3PO4 photocatalyst that is fabricated, using a facile precipitation method, from AgNO3 and Na2HPO4⋅12H2O. The material characterizations were carried out using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area, Fourier transform infrared (FTIR) absorption, Raman scattering, x-ray photoelectron spectroscopy (XPS), UV-vis absorption, and photoluminescence (PL). The results show that Ag3PO4 crystallizes better when the excess content increases, and the lattice parameters decrease slightly, while the crystal diameter and the particle size increase. This change is also observed in the Raman scattering and FTIR spectra with the increase in the vibration frequency of the [PO4] group. The compression of the [PO4] unit was also confirmed in the XPS spectra with the shift of P 2p peaks toward higher binding energy. The photocatalytic results showed that the samples synthesized from excess solution exhibited higher photocatalytic performance compared to the sample with a Ag+/ ratio of 3:1. A sample prepared from the precursor solution with a Ag+/ ratio of 3:1.5 was optimal for RhB decomposition under both visible light and natural sunlight, completely decomposing 10 ppm RhB after 15 minutes of xenon lamp irradiation and after 60 minutes under solar light irradiation. This is attributed to the high crystallinity, small particle size and low electron–hole recombination rate of the sample.

The promotion of Ag3PO4 photocatalysis on methylene blue removal and electricity generation in microbial fuel cell

The photocatalysis promoted microbial fuel cell (photo-MFC) system is designed to improve the degradation efficiency of recalcitrant organic pollutants in wastewater. In order to avoid the damage of UV light and reactive oxygen species to microorganisms, narrow bandgap Ag3PO4 photocatalyst is chosen and separated with TiN bioanode in anode chamber of MFC. Under visible light irradiation, the synergistic effect between photodegradation and biodegradation yielded a decolorization efficiency of 95.8% MB and a maximum power density of 2.90 W m−2 for 10 mg L−1 MB co-substrate with sodium acetate. The chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies of co-substrate in the photo-MFC system are 83.21% and 72.47%, much higher than that of photocatalysis alone (8.67% for COD and 9.65% for TOC). All of the degradation efficiency, power density and mineralization capacity of the photo-MFC system are higher than that of single MFC or photocatalysis. Microbial community analysis shows that Pseudomonas (73.75%) and Geobacter (19.62%) are the main genera of the bioanode in the photo-MFC system. The abundance of Pseudomonas is increased by photocatalysis. This photo-MFC coupled system has great potential application in wastewater treatment and energy recovery.

ENHANCE A PHOTOCATALYTIC ACTIVITY ON Ag3PO4 BY Ag\Ag3PO4 COMPOSITES

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.

Effectiveness Study of Using HAp Milkfish Bone to Synthesize Ag<sub>3</sub>PO<sub>4 </sub>with Ion-Exchange Method for Methylene Blue Degradation

The development of Ag3PO4 photocatalyst for dye waste treatment is necessary because of its superiority compared to other materials. In this research, Ag3PO4 was synthesized with AgNO3 and HAp from milkfish bones. Syntesis was done by simple ion-exchange method. In this research, composition of AgNO3:HAp are 1:0.1; 1:0.3; and 1:0.5 to determine the optimum composition. Based on XRD results, it shows that ion-exchange process between phosphate ions from HAp milkfish bones and Ag+ from AgNO3 was imperfect. It was shown from the presence of HAp peaks in synthesis results. Furthermore, the diffraction pattern showed that AgNO3:HAp 1:0.1 composition has the best cristalinity. Based on SEM characterization, it shows that all compositions have majority shape as spherical and small part at AgNO3/HAp 1:0.5 composition has nanorod morphology. It was also known that material with composition of AgNO3:HAp 1:0.1; 1:0.3 and 1:0.5 have average size are 100.76 nm, 92.31 nm and 107.51. From UV-Vis spectroscopy data processing, it represent the value of direct band gap of material is 3.83 eV and the value of indirect band gap is 3.6 eV. It also shows the degradation value of methylene blue with the best value was shown in AgNO3:HAp 1:0.3 composition with 47.4%.

The enrichment of silver ions in Ag3PO4 through the morphology changes and their photocatalytic activities

The Ag3PO4 photocatalyst has been developed to degrade the organic pollutant due to its highly active responsive under visible light irradiation. The properties of Ag3PO4 may depend on design and preparation. Starting materials and co-precipitation conditions would significantly affect the properties of the product. The controlled defect of this photocatalyst may lead to improve catalytic activity. Here, the unique properties of phosphate deficiency in Ag3PO4 were created using the starting material of KH2PO4 and AgNO3 under a mixed solvent of water and ethanol. AgNO3 solution with the ethanol percentages of 0%, 25%, 50%, 75% and 90% was added to KH2PO4 aqueous solution. The photocatalysts were characterized using XRD, DRS, SEM, and XPS. The changes in morphology can be observed from the tetrahedral to the sphere which has smaller particles. The increased atomic ratio of Ag/P and Ag/O suggests that the silver ion enrichment in Ag3PO4 has been created. The activity of Ag3PO4 for Rhodamine B elimination increased by 4.3 times higher compared to that of the pristine Ag3PO4. The enhanced photocatalytic activity might be caused by the smaller particle size and higher silver ion content on the surface of Ag3PO4.

A mechanistic study on photocatalytic activity of hydrothermally synthesized titanium dioxide nanowires decorated by silver phosphate

Heterostructure semiconductors have attracted increasing attention in the energy, environment, and catalysis domains. This study employed the hydrothermal method to synthesize titanium dioxide nanowires (TNWs) from TiO2–P25 nanoparticles. An effective strategy was used for coupling TNWs with a proper semiconductor with a narrow bandgap (Ag3PO4) for the purpose of enhancing absorption capacity in the visible light area and preventing the recombination of the photo-generated electrons and holes. The Ag3PO4/TNWs heterostructures consisted of Ag3PO4 nanoparticles firmly attached to the TNWs surfaces in varying ratios. The synthesized nanostructures were investigated by the Transmission Electron Microscopy (TEM), BET-BJH, and UV–Vis Diffusion Reflectance Spectra (DRS) techniques, as well as the X-ray diffractometer instrument. The photocatalytic degradation of RhB showed that the Ag3PO4/TNWs heterostructures manifested better photocatalytic performance than the pure TNWs and Ag3PO4. Likewise, the Ag3PO4/TNWs heterostructure photocatalyst reduced the loading of the noble Ag metal and thus decreased the practical application costs of the Ag3PO4 photocatalyst. A detailed mechanism study revealed the effective roles of holes and anion radical superoxides in the photocatalytic activity of the Ag3PO4/TNWs heterostructures.

Novel Z-scheme Sr2MgSi2O7:Eu2+,Dy3+/Ag3PO4 photocatalyst for round-the-clock efficient degradation of organic pollutants and hydrogen production

The photocatalytic reaction can carry out only under light irradiation, which limits the application of photocatalytic technology in the wastewater treatment and hydrogen production under no-light condition. In this study, Sr2MgSi2O7:Eu2+,Dy3+ with unique luminescence property was combined with Ag3PO4 to construct a novel Z-scheme Sr2MgSi2O7:Eu2+,Dy3+/Ag3PO4 photocatalyst. The morphology, structure, luminescence and photoelectric properties of the prepared samples were investigated by various characterization techniques. Some important influencing factors such as the mass ratios of Sr2MgSi2O7:Eu2+,Dy3+ and Ag3PO4, illumination times and cycling times were investigated. The results indicate that the Z-scheme Sr2MgSi2O7:Eu2+,Dy3+/Ag3PO4 photocatalyst with the best mass ratio (15:1) possesses superior photocatalytic activity. The LEV degradation rate is 81.94 % and the hydrogen production reaches 491 μmol/g under simulated sunlight irradiation for 1.0 h. The long-afterglow Sr2MgSi2O7:Eu2+,Dy3+ material can continue to support the photocatalytic reaction even after the light is turned off. The final LEV degradation is 86.84 % and the final hydrogen production amount reaches 591 μmol/g after the light is turned off for 3.0 h. Meanwhile, the process and possible mechanism of the round-the-clock photocatalytic LEV degradation with simultaneous hydrogen production were reported for the first time. This work cleverly uses the long-afterglow Sr2MgSi2O7:Eu2+,Dy3+ material combined with Ag3PO4 to form a novel Z-scheme photocatalyst, which realizes the organic pollutant degradation with simultaneous hydrogen production under the light on/off conditions, providing a new strategy for the round-the-clock efficient utilization of the photocatalyst.

Nanoemulsification synthesis route for obtaining highly efficient Ag3PO4 photocatalytic nanomaterial

Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3PO4 at room temperature. X-ray powder diffraction analysis and Raman spectroscopy reviled that synthesized powder was single-phase. Using scanning electron microscopy analysis, it was found that the synthesized Ag3PO4 particles were near-spherical shape with an average diameter of 100 nm. The high value for the specific surface area of obtained powder was measured by Brunauer?Emmet?Teller method. Finally, the Ag3PO4 product was used as a photocatalyst for the photodegradation of crystal violet dye in an aqueous solution. Nanoemulsion strategy procedure provides a simple pathway to obtain a highly efficient single-phase Ag3PO4 photocatalyst.

Surface modification of Ag3PO4 using the alginate for highly active photocatalyst under visible light irradiation

Surface modification of Ag3PO4 using alginate has been successfully synthesized. Ag3PO4 was prepared by precipitation method using CaHPO4/hydroxyapatite composite as a source of phosphate ion and AgNO3 ethanol solution. Alginate was introduced on the surface of Ag3PO4 under the chemisorption method. Products were analyzed using XRD, DRS, PL spectra, FTIR, SEM, TEM, and XPS. A small band edge absorption at 729 nm was created after surface modification using alginate. XPS analysis showed that the binding energy shifts of 0.3 eV and 0.5 eV were observed after alginate treatment for Ag3d and P2p respectively indicating that the alginate was successfully chemically bound to the Ag3PO4 surface. The alginate-modified Ag3PO4 photocatalyst showed much higher photocatalytic activity than pure Ag3PO4. The high activity is caused by the formation of conjugates that can act as electron donors under visible light irradiation.

Effect of H2O2 Addition on the Photocatalyst Properties of Ag3PO4 for Methylene Blue Photodegradation

In this work, a facile enhanced property of Ag3PO4 photocatalyst using H2O2 for methylene blue photodegradation has been conducted. Ag3PO4 photocatalyst was synthesized using the co-precipitation method. Then, the photocatalytic activity and stability of Ag3PO4 were tested in the methylene blue degradation under the addition of an H2O2 30% solution. According to the results, the prolonged photocatalysis reaction led to a decrease in the catalysis ability of the Ag3PO4 photocatalyst. Meanwhile, the addition of 5 mL of H2O2 (AH-10% sample) tends to enhance the stability of Ag3PO4 photocatalyst with the dye removal percentage and recycling test were up to 90.3% and three recycle runs, respectively. The low stability of Ag3PO4 might be due to the catalyst photo-corrosion through Ag+ reduction. This research suggests that H2O2 is beneficial to inhibit the photo-corrosion of Ag3PO4 photocatalyst, even though released Ag ions that were caused by the excess addition of H2O2 oxidizing agent should be considered.

Fabrication of binary Ag3PO4 photocatalysts for enhanced photocatalytic degradation: Effect of PEDOT hole conductor and hybridized 1 T-containing MoS2 electron conductor

Photocatalytic activity of Ag3PO4 has been improved through the addition of poly(3,4-ethylenedioxythiophene) (PEDOT) hole conductor or 1 T-containing MoS2 electron conductor. The binary Ag3PO4 composites were synthesized using a facile ion-exchange and chemisorption method. The photocatalytic performance of the composites was evaluated through the photodegradation of methylene blue (MB) and tetracycline (TC) under solar light irradiation. the addition of PEDOT or 1 T-containing MoS2 significantly improves the visible light absorption and effectively enhances the charge separation of photogenerated electrons/holes. Photocatalytic mechanisms are proposed for both the PEDOT/Ag3PO4 and MoS2/Ag3PO4 composites. We demonstrate that the PEDOT/Ag3PO4 composite exhibits a Z-scheme mechanism where the conversion of oxygen (O2) to superoxide radical (∙O2–) occurs at the PEDOT and the formation of hydroxyl radical (∙OH) occurs at the Ag3PO4. For the MoS2/Ag3PO4 composite, the 1 T-containing MoS2 acts as a co-catalyst to accept the photogenerated electrons from the Ag3PO4. Also, due to its metallic property, the1T-containing MoS2 reduces charge transfer resistance. As a result, the MoS2/Ag3PO4 exhibits superior MB and TC photodegradation performances, giving efficiencies of 99% and 93%, respectively, under solar light irradiation.

THE ENHANCED PHOTOCATALYTIC PROPERTIES OF SILVER PHOSPHATE SYNTHESIZED UNDER MANGOSTEEN PEEL EXTRACT SOLUTION

The synthesis of silver phosphate (Ag3PO4) photocatalyst has been widely developed for organic pollutant degradation. However, the large particle of this photocatalyst limits the photocatalytic activity. The smaller particle size of the Ag3PO4 photocatalyst was successfully prepared using the starting material of AgNO3 and Na2HPO4.12H2O under mangosteen peel extract solution. The starting materials were dissolved in mangosteen peel extract solutions prepared at the concentration of 1% (w/v). The reaction of silver nitrate and phosphate solution was conducted at room temperature. The samples of pristine Ag3PO4 and Ag3PO4 prepared under mangosteen peel extract were studied using XRD, DRS, SEM, BET, and FTIR. All photocatalytic activities were evaluated using Rhodamine B photooxidation under blue light irradiation (LED, 3 Watt). The results showed that the mangosteen peel extract significantly decreased the particle size, lowered the bandgap energy from 2.12 to 2.00 eV, and increased the crystallinity of Ag3PO4. The interaction of xanthones from mangosteen peel extract solution with silver ion might affect the growth particle of Ag3PO4, and inhibit the agglomeration leading to small particle size, more uniform distribution, high crystallinity, and low bandgap energy. These properties enhanced the photocatalytic activity up to 2.9 times higher compared to the sample without the treatment of mangosteen peel extract.

Porous biochar supported Ag3PO4 photocatalyst for “two-in-one” synergistic adsorptive-photocatalytic removal of methylene blue under visible light irradiation

The synergistic adsorption and photocatalysis is of importance to pollutant degradation, and thus the design of both adsorption and photocatalytic sites on one site of the catalyst is worthy of investigation. In the work, a bamboo biochar with rich porous structure was synthesized to support Ag3PO4 photocatalyst (AP/PBB) through a ball mill-pyrolysis-precipitation method. Owing to the large surface area of PBB, most of AP nanoparticles were well-dispersed and Ag0 species were in-situ generated in the preparation, which was beneficial for absorbing more visible light. Furthermore, a stronger interaction, i.e., built-in electric field between AP and PBB was observed, and thus the photo-generated electrons transfer quickly from AP to PBB via the Ag0 bridge. Furthermore, the transferred electrons reacted with the surface adsorbed oxygen species on PBB to produce ·OH radicals, and then oxidized the methylene blue (MB) molecules on PBB. Therefore, both adsorption and photocatalytic sites on one site, i.e., “two-in-one” of the AP/PBB photocatalyst exhibited higher MB degradation efficiency (95.6%), compared with AP/common biochar. This work affords a novel strategy for biochar-based photocatalysts for effective contaminant removal.