Pure Ag3PO4 Research Articles

Facile Fabrication of Novel S-scheme Ag3PO4/g-C3N4/Zeolite Photocatalyst for Boosting Photocatalytic Tetracycline Degradation and Hydrogen Production.

This study presents a novel ternary Ag3PO4/g-C3N4/zeolite composite for photocatalytic H2 production and TC degradation through S-scheme electron transport. The S-scheme Ag3PO4/g-C3N4 heterojunction was successfully constructed on zeolite surface through calcination and precipitation processes. The results indicated that Ag3PO4/g-C3N4/zeolite-50 % presented dramatically enhanced photocatalytic TC degradation performance, and the TC degradation efficiency was up to 92.86 % in 180 min under visible light. The corresponding reaction rate constant was 0.01205 min-1 which was 2.18 and 7.48 times greater than those of pure Ag3PO4 (0.00554 min-1) and g-C3N4 (0.00161 min-1), respectively. Meanwhile, the highest H2 production rate (2748.6 μmol g-1 h-1) was achieved over Ag3PO4/g-C3N4/zeolite-50 % under simulated solar light which was around 26.5 and 5.6 times higher than that of g-C3N4 and Ag3PO4, respectively. The enhanced photocatalytic activity of the ternary composite was mainly due to the synergistic effect of S-scheme Ag3PO4/g-C3N4 heterojunction and zeolite support which endowed the composite with excellent adsorption activity, enhanced light response ability, and efficient separation of photoinduced carriers. TC degradation mechanism and pathways were proposed based on quenching experiment and HPLC-MS results. Overall, this study proposes a promising strategy for significantly improving photocatalytic activity and applying in photocatalytic pollutant degradation and hydrogen production.

Catalyst efficiency through the disorder kinetics to identify its nonlinearity in their properties of Ag3PO4@TiO2 catalyst using UV–visible spectroscopy

Abstract Photocatalysis has a significant role in water remediation. During the process of photocatalysis, catalysts face different problems, such as instability and inefficiency. Here, we are introducing a new method, ‘nonlinearity kinetics’, which will help to identify this kind of problem during photocatalytic activity. We are considering Ag3PO4@TiO2 to study nonlinear disorder kinetics. Ag3PO4 is a highly photoactive compound with an inherent photocorrossive nature. Here, it addresses the challenge of pure Ag3PO4 by transforming composite materials to Ag3PO4@TiO2 and by studying its nonlinear kinetics during photocatalysis. The Ag3PO4@TiO2 underwent preliminary characterisation. Increment of crystalline nature studied through XRD. FESEM and TEM analysed morphological alignment and diffraction patterns. The functional behaviour of oxygen, Ag, Ti and P–O–P were identified through the FT-IR spectra. The reduced optical band gap Ag3PO4@TiO2 was 2.9 eV Obtained from the UV–visible spectra. Photocatalysis activity was performed, and newly introduced disorder kinetics were observed. The nonlinear fit of the kinetics shows a shift over time (intercept value of linear fit −0.27) that indicates the corrosive characteristics. For an efficient catalyst, this value must be equivalent to zero. The photocorrossive disorder kinetics study demonstrates the disorder and nonlinearity of the catalyst and catalytic medium when it does not fit with a linear fit. To identify a disorder, it is important to look at the disorder kinetics of analysis.

Synthesis of Bi-BiPO4-Ag3PO4/PAN composite nanomaterial photocatalyst with the degradation performance for rhodamine B

A highly efficient visible-light-driven photocatalyst Bi-BiPO4-Ag3PO4/PAN was synthesized by electrospinning, in-situ growth, immersion and reduction methods. The prepared composites were characterized by SEM, TEM, XPS, UV–vis, FT-IR and EIS. The results showed that the loading of BiPO4 significantly improved the photocatalytic efficiency of Ag3PO4, and the photocatalytic efficiency was further improved by a certain degree of reduction. When the ratio of BiPO4 to Ag3PO4 is 8 %, the catalyst: reducing agent is 1:2 and the reduction time is 15 min, the degradation rate of rhodamine B was the highest under visible light irradiation (λ ≥ 420 nm). The rate constant of Bi-BiPO4-Ag3PO4/PAN-8 % is (0.01401 min−1) 2.56 times that of pure Ag3PO4 (0.00327 min−1). The photocatalyst also has good degradation performance for different kinds of dyes and antibiotics under visible light irradiation, which is universal and easy to recycle. Free radical trapping experiments showed that •O2− is the main active oxidant affecting the photodegradation of rhodamine B and interacts with h+ and •OH. This study not only provides a new idea for the synthesis of Ag3PO4-based photocatalysts, it is also proved that Bi-BiPO4-Ag3PO4/PAN composite is a promising photocatalyst for the treatment of organic pollutants in water.

Construction of ZnCo2O4/Ag3PO4 composite photocatalyst for enhanced photocatalytic performance

AbstractIn this study, ZnCo2O4/Ag3PO4 composite catalyst was prepared by the precipitation method, and their performance in the photocatalytic degradation of methyl orange (MO) was studied. The catalysts were characterized by scanning electron microscopy, high‐resolution transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, selected area electron diffraction, X‐ray photoelectron spectroscopy, and UV‐Vis diffuse reflectance spectroscopy. The results indicate that the 0.1 ZnCo2O4/Ag3PO4 composite system has good photocatalytic activity in the degradation of methyl orange. Under simulated sunlight conditions, the degradation rate can reach 94% after 30 min. The maximum reaction rate constant of 0.1 ZnCo2O4/Ag3PO4 was 0.05301 min−1, which is 3 times and 52 times the rate constant of pure Ag3PO4 and pure ZnCo2O4, respectively. In catalyst recycling experiments, 0.1 ZnCo2O4/Ag3PO4 still degraded methyl orange at a rate of 84.4% after three cycles. Trapping experiments showed that holes and superoxide radicals mostly contributed to the photocatalytic degradation of methyl orange by the catalyst, while hydroxyl radicals played a partial role. The energy level structure of ZnCo2O4/Ag3PO4 is conducive to the effective separation of photogenerated electrons and holes, improving the lifespan of photogenerated charges. In the investigated catalyst series, 0.1 ZnCo2O4/Ag3PO4 demonstrated the best photocatalytic performance.

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.

Striking the balance: Unveiling the interplay between photocatalytic efficiency and toxicity of La-incorporated Ag3PO4

Persistent molecules, such as pesticides, herbicides, and pharmaceuticals, pose significant threats to both the environment and human health. Advancements in developing efficient photocatalysts for degrading these substances can play a fundamental role in remediating contaminated environments, thereby enhancing safety for all forms of life. This study investigates the enhancement of photocatalytic efficiency achieved by incorporating La3+ into Ag3PO4, using the co-precipitation method in an aqueous medium. These materials were utilized in the photocatalytic degradation of Rhodamine B (RhB) and Ciprofloxacin (CIP) under visible light irradiation, with monitoring conducted through high-performance liquid chromatography (HPLC). The synthesized materials exhibited improved stability and photodegradation levels for RhB. Particularly noteworthy was the 2% La3+-incorporated sample (APL2), which achieved a 32.6% mineralization of CIP, nearly three times higher than pure Ag3PO4. Toxicological analysis of the residue from CIP photodegradation using the microalga Raphidocelis subcapitata revealed high toxicity due to the leaching of Ag + ions from the catalyst. This underscores the necessity for cautious wastewater disposal after using the photocatalyst. The toxicity of the APL2 photocatalysts was thoroughly assessed through comprehensive toxicological tests involving embryo development in Danio rerio, revealing its potential to induce death and malformations in zebrafish embryos, even at low concentrations. This emphasizes the importance of meticulous management. Essentially, this study adeptly delineated a thorough toxicological profile intricately intertwined with the photocatalytic efficacy of newly developed catalysts and the resultant waste produced, prompting deliberations on the disposal of degraded materials post-exposure to photocatalysts.

Simultaneous degradation of SMX for efficient nitrogen fixation to ammonia and hydrogen evolution using AgVO3@rGO-Ag3PO4 (110) heterojunction

The simultaneous degradation of organic pollutants and generation of value-added compounds like ammonia and hydrogen energy has recently gained considerable attention in photocatalysis. The present study deals with successful preparation of novel AgVO3 nanowire@rGO-tetrahedral Ag3PO4 (110) (AGA) heterojunction and utilized for enhanced generation of NH3 and H2 from N-containing antibiotic sulfamethoxazole (SMX) under visible light. The prepared catalyst was well characterized by XRD, SEM, TEM and XPS to confirm the formation of heterojunction. The results indicated that the composite exhibited 546.0 μmol g−1 of hydrogen evolution rate, which is approximately 3.6 (153.6 μmol g−1) and 5.1 (108.7 μmol g−1) times higher than the pure AgVO3 and Ag3PO4 respectively after 6 h. Similarly, 38.3 mg L−1g−1 of NH3 generation was observed during 6 h of SMX degradation, which is about 1.9 and 2.8 times higher than the pure AgVO3 (20.1 mg L−1g−1) and Ag3PO4 (13.7 mg L−1g−1) respectively. The formation of heterojunction between AgVO3 and Ag3PO4 not only promotes the transfer of electron but also prevents the recombination which eventually enhances the catalytic conversion of N-element to NH3 and for H2 generation during water splitting. Furthermore, the plausible degradation pathway in SMX was proposed and the results revealed that the SMX was mineralized by the composite further converted to NH3 and generates H2 during the degradation process. Thus, our study provides new insights into novel photocatalytic treatment methodologies for simultaneous degradation of SMX to produce NH3 and H2 as value-added compounds from antibiotic wastewaters during water treatment process.

Ag3PO4/g-C3N4/Zn3(PO4)2 catalyst with ternary heterostructure and Z-scheme/type Ⅱ dual pathway mechanism for high photocatalytic performance

A novel Ag3PO4/g-C3N4/Zn3(PO4)2 photocatalyst with ternary heterostructure and Z-scheme/type Ⅱ dual pathway mechanism was synthesized. Scanning electron microscopy and transmission electron microscopy data showed that Ag3PO4, Zn3(PO4)2, and g-C3N4 were in close contact, leading to the formation of the ternary heterojunction. Under simulated solar light irradiation, the Ag3PO4/g-C3N4/Zn3(PO4)2 photocatalyst efficiently degraded rhodamine B (RhB) and displayed much higher photocatalytic activity than pure Ag3PO4, g-C3N4, Zn3(PO4)2, and Ag3PO4/Zn3(PO4)2 composite, exhibiting a RhB photodegradation efficiency of ∼91.2 % within 60 min. The quenching effects of different scavengers and electron spin resonance (ESR) experiments demonstrated that reactive h+ and·O2− species played major roles in the photocatalytic reaction. It was elucidated that excellent photocatalytic activity could be ascribed to the Z-scheme/type Ⅱ dual carrier transfer pathways. Therefore, the formation of a ternary heterostructure system is an efficient method for separating charge carriers and retaining their redox capabilities.

Ag3PO4/Bi2WO6 Heterojunction Photocatalyst with Remarkable Visible-Light-Driven Catalytic Activity

Novel Ag3PO4/Bi2WO6 catalysts with enhanced visible-light performance were synthesized using a hydrothermal method and characterized to investigate their morphology, microscopic structure, and binding energies. Photoluminescence spectrum (PL) and electrochemical impedance spectroscopy (EIS) data demonstrate that the formed Ag3PO4/Bi2WO6 heterojunction effectively promotes hole (h+)–electron (e−) separation and transfer efficiency, resulting in the enhancement of photocatalytic activity. Ag3PO4/Bi2WO6 displays higher photocatalytic activity than pure Bi2WO6 or Ag3PO4 alone. Photogenerated holes (h+), ·O2−, and ·OH were found to be the main active species for the degradation of malachite green (MG), methylene blue (MB), and Rhodamine B (RhB). The DFT calculation explains the photostability of Ag3PO4/Bi2WO6 from the perspective of electronic structure. The bandgap of Ag3PO4/Bi2WO6 between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) is 1.41 eV, compared with that of Ag3PO4 at 0.91 eV and Bi2WO6 at 2.59 eV. Ag–O–Bi hybridization and the wide HOMO–LUMO bandgap lead to difficulty in electron transfer. As a consequence, Ag+ is difficult to obtain electrons and difficult to convert into Ag0, which makes the catalyst stable.

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.

Modified silver phosphate nanocomposite as an effective visible-light-driven photocatalyst in the reduction of aqueous Cr(VI)

A simple precipitation technique was used to synthesize novel modified Ag3PO4 (AP) with Ag2S (AS) and reduced graphene oxide (G). XRD, FT-IR, Raman spectra, HR-TEM, XPS, UV-Vis, and PL, were used to investigate the physicochemical and optical properties of the as-prepared materials. The produced AS/G/AP nanocomposites exhibited a more visible-light response, diminished bandgap energy, and enhanced the charge separation rate. For the first time, the photocatalytic efficiency of modified Ag3PO4 nanocomposites was tested in aqueous Cr(VI) reduction under visible light illumination. After 45 min of irradiation and adapting the dose to 0.05 g/L, the optimized composite with 20 wt%AS (20-AS/G/AP) attained the maximum photo-reduction efficiency of 98.7% for Cr(VI) with a rate constant of 0.0734 min−1, which is almost 49 times higher than pure AP. The XPS analysis of the spent catalyst confirmed the distinctive Cr(III) peaks. Moreover, the photocatalyst showed notable reusability for four cycles without substantial activity loss. Finally, the photo-reduction mechanism of the catalyst was suggested.

Effect of indium (III) doping on Ag3PO4 catalyst stabilization and its visible light photocatalytic activity toward toxic dyes in water.

Indium(III)-doped Ag3PO4 (In-AgP) catalysts at different weight percentages were elaborated by co-precipitation and subjected to XRD, SEM, UV-vis DRS, and FTIR characterization. The prepared catalysts were of spherical morphology and their diameters depends on doping dosage. The whole materials crystallize in a centered cubic system with a slight dissimilation in the positions of the characteristic peaks as a function of indium dosage. The photocatalytic performance of the catalysts under visible light was investigated in the photocatalytic degradation of anionic dye (methyl orange (MO)) and cationic dye (auramine O (AO)) in moderate acid, neutral, and basic pH conditions. Results showed more selectivity to MO than AO. Furthermore, indium-doped samples are more active in the acidic medium than the pure Ag3PO4 (AgP), and 10%In-AgP catalyst presents the highest activity. The degradation efficiency reached 99 % in 60 min for MO and in 180 min for AO. In addition, a high recycling stability was achieved and the catalyst retains its degradation capacity above 99 % after five cycles.

Construction of bifunctional materials with high adsorption and deep photodegradation of bisphenol A by In-MOF decorated with Ag/Ag3PO4

Refining the visible light absorption and optimizing the separation of photogenerated electron-hole pairs are pivotal in enhancing the photocatalytic activity of composites. A novel Z-scheme plasma photocatalyst, Ag/Ag3PO4/In-MOF (A/AP/In), was developed in this study. Experimental results demonstrated that A/AP/In exhibited the highest photocatalytic activity for BPA among all samples tested, achieving complete degradation of 50 ppm BPA within 30 min, as well as its apparent degradation rate was about 11 times higher than that of pure Ag3PO4 and 4 times higher than that of pure In-MOF. The enhanced photocatalytic activity can be mainly attributed to the existence of Z-type heterojunctions and the surface plasmon resonance (SPR) effect induced by Ag nanoparticles, which facilitate efficient migration and separation of photogenerated carriers. Meanwhile, the incorporation of Ag nanoparticles enhances visible light absorption and protects Ag3PO4 from photocorrosion in the composites. Moreover, A/AP/In maintains the large specific surface area of In-MOF and provides abundant reactive active sites. In addition, the photocatalytic performance of A/AP/In was above 90 % after five consecutive cycles confirming its good stability. Overall, this study proposes a novel approach for constructing bifunctional composites with efficient adsorption/catalytic degradation.

Enhanced photocatalytic performance of Co3(PO4)2/Ag3PO4 immobilized on SiC: The synergistic effects and mechanism

Co3(PO4)2/Ag3PO4 (CoPi/AgP) were immobilized onto SiC nanowires through co-precipitation. Compared with Ag3PO4, the photoactivity and photostability of CoPi/AgP/SiC were significantly enhanced, while the cost was reduced because of the low demand for expensive Ag3PO4. Under visible light, Ag3PO4/SiC loaded with 0.5%Co3(PO4)2 achieved an apparent methyl orange (MO) degradation rate constant of 1.77 times higher than Ag3PO4 and 7.49 times higher than Ag3PO4/SiC. Moreover, after five reuses, Ag3PO4/SiC loaded with 0.5%Co3(PO4)2 maintained its photocatalytic activity at 87%, whereas pure Ag3PO4 retained only 32.5%. The synergistic action of the Z-scheme Ag3PO4/SiC heterojunction and Co3(PO4)2 cocatalyst led to enhanced photoactivity and stability. The weak internal electric field induced in Co3(PO4)2/Ag3PO4 significantly increased the intensity of the main internal electric field in Ag3PO4/SiC, resulting in a rapid interfacial transfer, prolonged lifetime, and strong redox ability of the photoinduced charge carriers. This mechanism demonstrates a positive effect on charge separation, oxidative reaction kinetics, and the formation of·OH of the Co3(PO4)2 hole cocatalyst. Density functional theory (DFT) calculations and active species trapping experiments confirmed the Z-scheme electron transfer pathway. Consequently, this study provides a low-cost method to construct a novel immobilized photocatalyst with high activity and stability for the efficient degradation of organic pollutants under visible light.

Fermi level induced band edge alignment and band bending in Ag3PO4/Cu2O p-n heterojunction for proficient photocatalytic applications

Fabrication of binary p-n heterojunction and the band alignment at the interface of the individual semiconductor photocatalyst has been extensively studied to verify superior charge separation and migration capability in photocatalytic applications. Here, a simple wet chemical followed by a hydrothermal fabrication strategy was introduced for the development of the binary p-n Ag3PO4/Cu2O heterostructures. The tunable band structure of individual semiconductors with the work function (φ), witnessed a band bending at the space charge region. The bending at the interface induces a carrier concentration gradient and manifests a rectifying current transport diode. The fabricated p-n heterostructures and carrier migration between n-type Ag3PO4 and p-type Cu2O were verified by different morphological and physicochemical methods. The band banding at the interface, leading to a narrow depletion region, favors the tunneling of electron-hole pairs through a Z-scheme carrier transport mechanism. The electron-hole pair movement has further been confirmed by considering the band edge position after contact, photocatalytic scavengers, and the radical trapping experiment. The Ag3PO4/Cu2O p-n heterojunction photocatalyst manifested a 737.4 μmol g−1h−1 of H2 generation and 91% endosulfan degradation efficiency, these are 12 and 9 times higher than that of pure Ag3PO4. The p-n heterojunction photocatalyst displayed a higher current density with electron-hole migration efficiency, synergistically enhancing the catalytic activity through the interfacial space charge junction.

Surface decoration of spherical Ag3PO4 with Ag embedded nano-cocoon BiPO4 nano-heterojunction photocatalyst with improved photodegradation of tetracycline hydrochloride and industrial dyes

Significant research interest has been focused on the development of superior visible-active photocatalysts. Herein, we have developed Ag hybrid p-n junction of Ag3PO4/BiPO4 via P123 assisted co-precipitation method at different molar ratios. An intergrowth structure composed of spherical Ag3PO4 decorated with nano-cocoon BiPO4 was found to be formed at optimized molar ratio. Thorough analysis reveals that Ag NPs with an average size of 9 nm have tightly scattered on the surface of the nano-cocoons BiPO4. The well heterostructure formation is an effective strategy to boost the photocatalytic activity of the materials. The photocatalytic activity of the heterostructure with an optimal molar ratio over tetracycline hydrochloride demonstrated 81.4% degradation in 30 min with a reaction rate 3.21 times faster than pure Ag3PO4. The use of an optimized photocatalyst extends the light absorption, diminishes the charge carrier recombination process with build in electric fields at the interface and carrier transfer across the p-n junction. Moreover, superoxide radical O2•− species are found to be participated dominantly in the photocatalytic reaction. Based on the findings, a plausible mechanism was developed to demonstrate the elevated photocatalytic activity. A real sample analysis of textile effluents and the degradation of dyes, including MB, RhB, CR, and MO, were also investigated.

In-Situ Hydrothermal Synthesis of Ag3PO4/g-C3N4 Nanocomposites and Their Photocatalytic Decomposition of Sulfapyridine under Visible Light

Highly efficient visible-light-driven heterogeneous photocatalyst Ag3PO4/g-C3N4 with different weight ratios from Ag3PO4 to g-C3N4 were synthesized by a facile in situ hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), photoluminescence spectra (PL), UV–vis diffuse reflectance spectra (UV-Vis), and electrochemical impedance spectra (EIS). Under visible light irradiation, Ag3PO4/g-C3N4 showed very excellent photocatalytic activity for sulfapyridine (SP) which is one of the widely used sulfonamide antibiotics. When the ratio from Ag3PO4 to g-C3N4 was 1:2, the degradation rate of SP at 120 min was found to be 94.1%, which was superior to that of pure Ag3PO4 and pure g-C3N4. Based on the experimental results, the possible enhanced photocatalytic mechanism of Ag3PO4/g-C3N4 was proposed.

A novel BiOCl (110)/rGO/Ag3PO4 (111) heterostructure for efficient detoxification of 2,4-dichlorophenol

An effective method using nontoxic and efficient photocatalysts are crucial for wastewater treatment. Bismuth oxychloride (BiOCl) is considered as one of the valuable photocatalysts due to its unique layered plate like structure, however higher recombination and unsatisfied visible light absorption efficiency seriously affecting its applications. Addition of tetrahedral silver phosphate (Ag3PO4) which is known for its superior photocatalytic efficiency under visible light is believed to be the solution for the issue. Upon further adding of reduced graphene oxide (rGO) could form a bridging structure and enhance the activity. Considering the merits of these materials the BiOCl (110)/rGO/Ag3PO4 (111) heterojunction has been successfully constructed for 2,4-dichlorophenol (DCP) enhanced detoxification. The efficiency in degradation was found to be 94.8% by BiOCl/rGO/Ag3PO4 (k = 0.01879 min−1) that was greater to that of pure Ag3PO4 (∼1.9 times; k = 0.00818 min−1) and pure BiOCl (∼2.8 times; k = 0.00642 min−1) after 60 min of visible light irradiation. The mechanism of degradation was explained through the principle of heterojunction energy-band theory. Furthermore, 2,4-dichlorophenol (2,4-DCP) degradation products identification was carried out by ESI/LC-MS to propose the degradation pathway. Furthermore, the phytotoxicity of the intermediate products was investigated by estimating the germination index (GI) values on Phaseolus vulgaris (P. vulgaris) at different time intervals and the GI values were found to be 10.79% and 80.17% before and after degradation respectively. Thus, our results revealed that efficient and significant toxicity reduction was observed in this photodegradation.

Comparative study of enhanced adsorption-photodegradation activity using activated biochar composited with Ag3PO4 or Ag6Si2O7 in wastewater treatment and disinfection: Effects and mechanisms

To efficiently remove organic pollutants from wastewater combined with a disinfection effect, using activated biochar (ACB) as substrate, ACB-Ag3PO4 and ACB-Ag6Si2O7 composite photocatalysts were prepared via the in-situ co-precipitation method. The structure, morphology, physicochemical, and optical properties were characterized by advanced techniques, and the adsorption-photodegradation effects on tetracycline (TC), chloramphenicol (CAP), and rhodamine B (RhB) were investigated. The results revealed that ACB-Ag3PO4 and ACB-Ag6Si2O7 with heterojunction were successfully synthesized, and their optimum loading ratios were 1:1 and 1:2, respectively. The removal rates of ACB-Ag3PO4 and ACB-Ag6Si2O7 for TC were 98.48% and 91.87%, 95.88% and 85.23% for CAP, 99.13% and 83.54% for RhB, respectively, and also much higher than those of pure Ag3PO4 and Ag6Si2O7. Moreover, the degradation efficiency and mineralization rate of ACB-Ag3PO4 were higher than those of ACB-Ag6Si2O7 for all pollutants. Further, both composites maintained about a 99% sterilization rate against both S. aureus and E. coli at 48 h. These were attributed to the introduction of ACB, which enriched the elemental composition of Ag-based semiconductors and increased the specific surface area and visible light absorption. Importantly, the composites narrow the bandgap energy and optimize energy band structure, and the special structure of ACB facilitated the photocatalytic activity. Moreover, possible photogenerated carrier transfer paths of the two composites are either type-II or Z-scheme, and the performance differences are related to the photogenerated carriers, absorbance, and microstructure. ACB-Ag3PO4 is more recommended for environmental applications given its better photostability and reusability than ACB-Ag6Si2O7, and its removal of TC and RhB from actual wastewater exceeded 61.39% and 86.62%, respectively.

Construction of an all-solid-state Z-scheme Ag@Ag3PO4/TiO2-(F2) heterostructure with enhanced photocatalytic activity, photocorrosion resistance and mechanism insight

Photocatalysis is still a promising technology to alleviate the antibiotic residual problem of wastewater in the ecological environment. Herein, an all-solid-state Z-scheme Ag@Ag3PO4/TiO2-(F2) (TFAP) heterojunction photocatalyst was constructed using the hydrothermal method for the first time. The photocatalytic performance of TFAP nanocomposites for tetracycline hydrochloride (TCH) degradation was evaluated under simulated sunlight. The prepared materials were characterized by XRD, FE-SEM, TEM, BET, FT-IR, UVvis DRS, XPS, PL, and ESR measurements. The TFAP nanocomposites showed high degradation efficiency and excellent repeatability to TCH destruction. Among them, the (TFAP 1–1) nanocomposite has a lower bandgap energy (1.80 eV), a larger specific surface area (53.48 m2/g), and a lower electron-hole recombination rate. After 2.5 h of simulated sunlight irradiation, the degradation rate of the 200 mg/L (TFAP 1–1) nanocomposite (k = 0.0154 min−1) to 10 mg/L TCH reached 94.14%, which was much higher than that of the pure TiO2, TiOF2, and Ag3PO4 samples. The experimental results demonstrated that TiO2 was generated as an intermediate product during the chemical reaction process between Ag3PO4 and TiOF2. Additionally, Ag nanoparticles were formed in the Ag3PO4/TiO2/TiOF2 heterojunction system. An electric field was formed between Ag3PO4 and Ag, enhancing the visible light absorption ability. Because of the Schottky potential difference, the electrons accumulate in Ag nanoparticles, thus enhancing the photocorrosion resistance of Ag3PO4. Additionally, the localized surface plasmon resonance (LSPR) effect of Ag nanoparticles greatly promoted the separation of carriers at the interface of the heterojunction. The LSPR effect leads to the co-oscillation of free electrons, which leads to the strong absorption of electromagnetic energy and enhances the photocatalytic performance of the heterojunction. The Ag@Ag3PO4 nanocomposites acted as electron transport media for an all-solid-state Z-scheme TFAP heterojunction system. This study provides some in-depth insights into the structural design of Z-scheme heterojunctions, which have certain implications for other catalytic systems.