Lower Electron-hole Recombination Rate Research Articles

Study on the performance of photothermal catalyzed carbon dioxide hydrogenation to CH4 over doped sodium tantalate-based perovskite catalysts

NaTaO3 (ABO3)-based catalysts with B-site substituted metals M= (Co, Ni, Fe, Ga, Ti) for photothermal-catalyzed carbon dioxide reduction hydrogenation to C1 products were prepared via a simple one-step hydrothermal method. The B-site metal doping catalysts exhibited excellent performance for the aimed photothermal catalytic reaction. Among them, the NaTa0.9Co0.1O3 was the most eye-catching catalyst with a stable crystal cell, an excellent heterojunction structure, and a bandgap structure for light absorption, The fine structure properties results in a low electron-hole recombination rate and high photoelectron transfer efficiency under light conditions. The suitable alkaline adsorption sites and thermal reduction properties also be the effective assistance for the catalytic process. The CO yield and CH4 yield of the NaTa0.9Co0.1O3 catalyst were 6.6 times and 120 times higher than those of the pure-phase NaTaO3, respectively, and the CH4 selectivity was up to 98% under the illumination condition of 300 ℃. For the photothermal hydrogenation reaction, thermal catalysis dominates the reaction, and light illumination promotes the generation and transfer of photogenerated electrons and improves the catalyst stability. The above studies show that NaTaO3 based perovskite has a great potential in the field of photothermal catalyzed carbon dioxide reduction.

A new approach to the synthesis of CuMoO4 nanoparticles with mechanistic insight into the sunlight-assisted degradation of textile pollutants and antibacterial activity evaluation

CuMoO4 nanoparticles (NPs) were synthesized by a thermal decomposition followed by a precipitation method. Analytical techniques such as SEM, EDS, TEM, XRD, FTIR, UV-visible, PL, and XPS were employed to characterize the structural, optical and photocatalytic properties of CuMoO4. As per XRD analysis, CuMoO4 with different Cu concentrations were consistent, however, their crystallinities were changed. The band gap of CuMoO4 with various concentrations of Cu (0.1, 0.2, and 0.3M) was estimated to be 1.97eV, 1.86eV, and 1.44eV, respectively. The electrical conductivity of 0.3M CuMoO4 NPs was greater than other nanocomposites. Methylene Blue (MB) mineralization in an aqueous medium after 180minutes of exposure to sunlight was investigated to study the photocatalytic activities of all CuMoO4 composites. As per the PL study, the 0.3M CuMoO4 NPs exhibited better photocatalytic efficiency due to their low electron-hole recombination rate. Experimental parameters like the MB concentration, catalyst dosage, and the solution pH were evaluated to optimize the experimental conditions. The in-situ capture analysis proposed a plausible mechanism for the photocatalytic degradation of MB. The two main active species identified for MB degradation were superoxide radical anions and hydroxyl radicals. The repeated photocatalytic MB degradation verified the high level of reusability of 0.3M CuMoO4. The well-diffusion technique was utilized to examine the antibacterial activity of 0.3M CuMoO4 NPs against gram-positive (Salmonella typhi) and gram-negative (Streptococcus mutans) bacterial strains. Optimized CuMoO4 showed excellent promise for application in the field of photocatalysis, electrocatalytic and antibacterial activity.

High temperature synthesis, surface characterization, and photoluminescence property of boron carbon nitride

The present study demonstrates the synthesis of boron carbon nitride (BCN) by molten salt method which utilizes melamine (source of carbon and nitrogen), boric acid (source of boron) and potassium chloride as the salt. The synthesis is performed at 915 °C for 4 h under N2-atmosphere. The synthesized material is further acid-treated. The physicochemical characterization data for as-synthesized and acid-treated materials confirm successful synthesis of BCN. SEM and AFM data display that synthesized BCN pre and post acid-treatment exhibit sheet-type morphology. Thermogravimetric analysis data confirm that the acid-treated material is thermally stable up to 800 °C, with only 2 % mass-loss is observed till 800 °C. Water contact angle measurement study demonstrates that acid-treatment significantly improves the surface hydrophilicity. Additionally, the low photoluminescence peak intensity of the acid-treated material indicates low electron-hole pair recombination rate. The synthesized material may be useful for the photocatalytic degradation of potentially toxic chemicals from water.

Effect of aging times of fibrous silica cadmium sulfide photoanodes for enhanced photoelectrochemical water splitting

The use of photoelectrochemical (PEC) water splitting to produce hydrogen from solar sources is an alluring potential address to the world’s energy and environmental problems. Cadmium Sulfide (CdS) is a potentially visible light response photoanode of PEC water splitting, but practical use remains a significant barrier due to its low charge carrier separation efficiency. To address this disadvantage, modifications to the morphology of CdS is necessary. Herein, fibrous silica cadmium sulfide (FSCdS) photoanode for PEC water splitting was synthesized using microemulsion method reported in this study. In this study, it will be focused on the effect of aging times which is 6 hours and 8 hours on the structure of FSCdS towards the PEC water splitting. The physicochemical and electrical properties of the photoanodes were investigated using XRD, UV-Vis DRS, FTIR and EIS Nyquist Plot. FSCdS-6H had a higher photocurrent density of 22.1 mA/cm2 at 1.23 VRHE and a higher solar-to-hydrogen (STH) efficiency of 27.2% when compared to FSCdS-8H with 13.0 mA/cm2 and STH of 16.0%. This is due to the better crystallinity, higher Si-Cd-S interaction, and lower electron hole recombination rate of FSCdS-6H photoanode. Fabrication of fibrous silica-based photoanodes revealed significant insight for the creation of highperformance photoanodes for improved PEC water splitting performance.

Synergistic Optimization of Morphology and Vacancies on Diatomic Rhodium Catalysts Dispersed on Carbon Nitride for Efficient Photocatalytic Reduction of CO2

AbstractDiatomic site catalysts (DAC) have better performance with higher metal content and more flexible active sites compared with single atomic site catalysts (SAC). Herein, the authors for the first time achieved Rh2 DAC on loose porous g‐C3N4 hollow nanospheres with N‐vacancies and applied to photocatalytic CO2 reduction reaction, overcoming the current limitations of the low electron–hole recombination rate and prolong the lifetime of the photogenerated carrier. The high specific surface area of hollow nanosphere facilitates the uniform dispersion and anchoring of Rh2 diatomic pairs, while the N‐vacancies induce a stable 3N/Rh‐Rh/1N2C coordination between the carrier and Rh2 diatomic pairs. The local charges on the support framework with N vacancies tend to be transferred to Rh2 diatomic site by 3N/Rh‐Rh/1N2C bridge, which made the charge enriched Rh2 diatomic site become the active center of reaction, enhance charge separation efficiency of Rh2/HCNS‐Nv. Compared with Rh1 SAC, further Density Functional Theory (DFT) calculation confirms that Rh2 DAC can effectively stabilize rate‐limiting intermediates CHO*, and well weaken the C─O bond strength in CH3O* species, promote the generation and separation of CH4, resulting in high CO2 reduction efficiency and CH4 electron selectivity of up to 91.65%.

Construction of Z-scheme NiO/BiOBr heterojunction for facilitating photocatalytic degradation of oxytetracycline and 2-mercaptobenzothiazole

Z-scheme NiO/BiOBr heterojunction was prepared by mechanical ball milling method and applied for the photodegradation removal of oxytetracycline (OTC) and 2-mercaptobenzothiazole (MBT). The Z-scheme electron transport pathway optimizes the separation of photogenerated carriers, thereby significantly increasing the generation capacity of reactive oxygen species (ROS). The photocatalytic degradation experiments demonstrate that the optimized OTC and MBT removal efficiency of NiO/BiOBr (NBOB) composites could reach 72.6% (120 min) and 97.7% (9 min), respectively. Photoluminescence (PL) spectra and PL decay curves indicate that NBOB-2 composites exhibit low photoinduced electron-hole recombination rate and accelerated electron separation efficiency. In addition, ESR spectra confirm that the Z-scheme NiO/BiOBr heterojunction can generate a larger quantity of ROS species. The possible photodegradation pathways and toxicity analysis for the OTC and MTB photodegradation intermediates are elucidated by HPLC-MS measurement and T.E.S.T. application. The manuscript provides a reference for the macro-preparation of bismuth-based photocatalysts with superior performance and high stability.

Step-by-step tuning of morphology and band gap of ZnS/MoS2 photocatalyst for enhanced visible light to hydrogen fuel conversion

To address the inherent limitations of ZnS and MoS2 as visible light photocatalysts, herein, we report a step-by-step tuning of mixed sulfide composite system (ZnS/MoS2) to achieve enhanced visible light to hydrogen fuel conversion efficiency in the absence of any sacrificial agents. In the first stage, ZnS/MoS2 composite was synthesized by using a single step hydrothermal route and the photocatalytic activity of the synthesized ZnS/MoS2 composite was tuned by varying the ratio of Zn and Mo in the composite. In the second stage, the photocatalytic efficiency of the composite was further enhanced by tuning the band gap and visible light absorption characteristics of the material through cobalt doping (Co-doping) in the MoS2 co-catalyst. The hydrogen generation activity of the tuned composition (1:1.3 ratio of Zn and Mo) of the ZnS/MoS2 composite with 3% Co-doping is obtained as the best (1256 μmol of H2 in 1 h) as compared to the other compositions of the doped composites (1%, 3% and 5% Co doping). The enhanced hydrogen generation through visible light induced water splitting of the developed mixed sulfide composite systems (ZnS/MoS2 and ZnS/Co-doped MoS2) even in the absence of any sacrificial agents is ascribed to their tuned band gap and low electron-hole recombination rate.

Construction of Novel Z-scheme Heterojunction in ZnFe2O4/P25 @ MOF-5 Nanocomposite from Plastic Waste for Efficient Photodegradation of Aqueous BTX Under Visible Light

AbstractAn innovative strategy to reduce water pollution is adsorption-assisted photocatalysis. A novel mesoporous heterogeneous adsorbent MOF-5-based photocatalysts were successfully synthesized by a green method from plastic waste through a one-step solvothermal process. Additionally, ZnFe2O4 nanocrystals were physically ground with commercial Degussa P25 at room temperature to prepare ZF/P nanocomposite catalysts. These catalysts demonstrated significant photocatalytic activity for the removal of BTX from wastewater. BTX was successfully degraded in an aqueous solution utilizing integrated adsorption and photocatalytic degradation using the newly developed ZF/P@MOF-5 samples with 0.01% of ZF/P. The in-depth characterization of the ZF/P@MOF-5 confirmed its positive physicochemical properties, such as porous nature, stability, high surface area, beneficial functional groups on its surface, and photocatalytic activity. PL spectroscopy also shows that the ZF/P-incorporated MOF-5 nanocomposite has a lower electron-hole recombination rate. The as-prepared ZF/P@MOF-5 mesoporous heterogeneous adsorbent-photocatalyst presented high adsorption and maximum degradation of BTX under visible radiations after 180 min. The reusability results demonstrated that 20 P/ZF @MOF-5 composite can be used effectively for up to four cycles, which makes the process more economical. This experimental study demonstrates that the novel ZF/P-incorporated MOF-5 is a potential route to producing photocatalysts for dissociating BTX wastewater that is highly effective, stable, economical, and sustainable.

Degradation of enrofloxacin by a novel Fe–N–C@ZnO material in freshwater and seawater: Performance and mechanism

In this study, we investigated the doping of Fe–N–C with ZnO (Fe–N–C@ZnO) to enhance its performance in the reduction of biological toxicity and degradation of enrofloxacin (ENR) in seawater. The steady-state/transient fluorescence analysis and free radical quenching test indicated an extremely low electron–hole recombination rate and the generation of reactive oxygen species in Fe–N–C@ZnO, leading to an improvement in the energy efficiency. We compared the ENR degradation efficiencies of Fe–N–C@ZnO and ZnO using both freshwater and seawater. In freshwater, Fe–N–C@ZnO exhibited a slightly higher degradation efficiency (95.00%) than ZnO (90.30%). However, the performance of Fe–N–C@ZnO was significantly improved in seawater compared to that of ZnO. The ENR degradation efficiency of Fe–N–C@ZnO (58.87%) in seawater was 68.39% higher than that of ZnO (34.96%). Furthermore, the reaction rate constant for ENR degradation by Fe–N–C@ZnO in seawater (7.31 × 10−3 min−1) was more than twice that of ZnO (3.58 × 10−3 min−1). Response surface analysis showed that the optimal reaction conditions were a pH of 7.42, a photocatalyst amount of 1.26 g L−1, and an initial ENR concentration of 6.56 mg L−1. Fe–N–C@ZnO prepared at a hydrothermal temperature of 128 °C and heating temperature of 300 °C exhibited the optimal performance for the photocatalytic degradation of ENR. Based on liquid chromatography–mass spectrometry analysis, the degradation processes of ENR were proposed as three pathways: two piperazine routes and one quinolone route.

Interfacial charge separation of nickel tungstate anchored on g-C3N4 heterojunction stimulates visible-light driven direct Z-scheme photoelectrochemical hydrogen evolution

Active photocathodes are required for the photo(electro)chemical hydrogen evolution reaction (PEC-HER) in a highly efficient solar-to-hydrogen fuel conversion process aided by solar assisted water splitting. Here, we used a simple one-pot solvothermal method to prepare NiWO4/g-C3N4 nanocomposites for PEC-HER using low-cost, metal-free photocatalysts such as graphitic carbon nitride (g-C3N4) and nickel tungstate (NiWO4). Subsequently, the physicochemical and optoelectronic nature of the as-synthesized materials were studied by spectroscopic methods. As part of a direct Z-scheme heterogeneous mechanism, the photoactive module, g-C3N4 was blended with NiWO4 in varying ratios to enhance the efficiency of charge separation in PEC-HER. As expected, the established NiWO4/g-C3N4 nanocomposite demonstrates an enhanced photo(electro)catalytic activities compared to the single components. It is firmly due to the presence of intimate interfacial interaction between g-C3N4 and NiWO4, which further supports the existence of electrons in the conduction band of g-C3N4 and holes in the valence band of NiWO4. The prepared NiWO4/g-C3N4 nanocomposite with 15 wt% of g-C3N4 showed an enhanced photocurrent density of 167.81 mA cm−2, which is higher than that of other prepared photo(electro)catalysts and confirms its excellent charge separation efficiency as well as very low electron-hole recombination rate. Besides, the photoelectrochemical activities of the prepared materials were analysed through a PEC-HER, revealing that the developed NiWO4/g-C3N4 nanocomposite as photocathode requires a low overpotential of 0.048 V to reach the current density of 10 mA cm−2 and a Tafel slope of 43 mV dec−1, indicating the superiority of the photo(electro)catalyst. In addition, the NiWO4/g-C3N4 photocathode exhibits excellent performance for PEC-HER with higher stability.

Understanding the effect of the calcination process on the structure of mesoporous silica zirconia photocatalysts for Bisphenol A degradation

The mesoporous silica zirconia (m- SiO2/ZrO2) was successfully synthesized in this study using a microwave method, and the effect of the calcination process was studied. In this study, half of the sample was left untreated (labeled "untreated sample"), while the other half was calcined at 850 °C for 3 hours in an air atmosphere in a muffle furnace to remove the surfactant. X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible differential reflectance spectroscopy, nitrogen adsorption-desorption spectroscopy, and electron spin resonance spectroscopy were utilized in order to analyze the catalysts that were produced. The findings from the characterization showed that the calcination procedure caused the creation of oxygen vacancies and increased the surface area, both of which affected the photocatalytic activity. The photocatalytic activity of the calcined m-SiO2/ZrO2 (80%) catalyst was superior to that of the untreated m-SiO2/ZrO2 (19%) catalyst. Zirconia's greater surface area and its natural occurrence in the tetragonal phase are both to blame for this phenomenon. In addition, there is the possibility that a greater proportion of oxygen vacancy will result in a smaller band gap and a lower electron-hole recombination rate. After five cycles, the photocatalytic activity exhibited by both catalysts remained unchanged.

Growth of 3D-TNAs@Ti-MOFs by dual titanium source strategy with enhanced photoelectrocatalytic/photoelectro-Fenton performance for degradation of tetracycline under visible light irradiation.

Visible-light-active 3D-TNAs@Ti-MOFs composite electrodes were fabricated by decorating nanoscaled Ti-based metal-organic frameworks on three-dimensional TiO2 nanotube arrays (3D-TNAs) prepared by a facile in situ solvothermal method. The photoelectrocatalytic performance of electrode materials was evaluated by degradation of tetracycline (TC) under visible light irradiation. The experiment results show that Ti-MOFs nanoparticles are highly distributed on the top and side walls of TiO2 nanotubes. The 3D-TNAs@NH2-MIL-125 solvothermally synthesized for 30 h exhibited the best photoelectrochemical performance compared with 3D-TNAs@MIL-125 and pristine 3D-TNAs. In order to further enhance the degradation efficiency of TC by 3D-TNAs@NH2-MIL-125, a photoelectro-Fenton (PEF) system was constructed. The influence of H2O2 concentration, solution pH and applied bias potential on TC degradation were explored. The results showed that when pH was 5.5, H2O2 concentration was 30 mM, and applied bias was 0.7 V, the degradation rate of TC was 24% higher than the pure photoelectrocatalytic degradation process. The enhanced photoelectro-Fenton performance of 3D-TNAs@NH2-MIL-125 could be attributed to the large specific surface area, excellent light utilization, efficient interfacial charge transfer, low electron-hole recombination rate and high production of ˙OH as the result of the synergistic effect between TiO2 nanotubes and NH2-MIL-125.

Construction of Benzodithiophene-Based Donor–Acceptor-Type Covalent Triazine Frameworks with Tunable Structure for Photocatalytic Hydrogen Evolution

The introduction of donor–acceptor (D–A) motifs into organic semiconductors has been considered as one of the effective strategies to regulate photocatalytic activity. Herein, D–A-type benzodithiophene-based covalent triazine framework materials (BDT-CTFs) have been reported. It has been shown that the valence band and conduction band positions, band gaps, and electron–hole separation efficiency can be adjusted by altering the D/A ratio in the BDT-CTF photocatalytic materials. It has been revealed that the high electron–hole separation, migration efficiency, and low electron–hole recombination rates, as well as the special D–A pore structures are the main reasons for the higher photocatalytic hydrogen evolution reaction (HER) activities of BDT-CTF-1 materials. This work revealed the structure–activity relationship in BDT-based CTFs with different D–A ratios, providing a strategy to develop organic photocatalysts with high performance.

Synthesis of visible-light driven CeO2/g-C3N5 heterojunction with enhanced photocatalytic performance for organic dyes

In order to improve the photocatalytic property of g-C3N5, series of CeO2/g-C3N5 composites were prepared by calcination method. Rhodamine B (RhB), methylene blue (MB) and methyl orange (MO) were degraded under visible light to reflect the photocatalytic activity of CeO2/g-C3N5 composites. The results showed that the specific surface area of 10 wt% CeO2/g-C3N5-400 composites was 28.2 m2 g−1, while g-C3N5 was 3.9 m2 g−1. According to UV-Vis and PL results, 10 wt% CeO2/g-C3N5-400 composites have enhanced visible light absorption and low electron hole recombination rate. Thus, 10 wt% CeO2/g-C3N5-400 composites exhibited excellent photocatalytic activity. The degradation rates of RhB and MB by 10 wt% CeO2/g-C3N5-400 composites were 71 % and 99 % after 150 min. But the removal rates of RhB by CeO2 and g-C3N5 were only 14 % and 26 %. Combining trapping experiments and EPR results, •O2- was the major active species in the photodegradation reaction. Sample 10 wt% CeO2/g-C3N5-400 composites also remained outstanding photocatalytic stability after 4 cycles. The possible photocatalytic mechanism was also elucidated. In a word, CeO2/g-C3N5 composites are promising for photodegradation of organic dyes under visible light.

Magnetic Fe3O4/Bi2O2(OH)(NO3) as a sunlight-driven photocatalyst for rhodamine B degradation

A magnetic separable photocatalyst based on Fe3O4/Bi2O2(OH)(NO3) was synthesized using a two-step method based on co-precipitation and a hydrothermal route. The photocatalytic activity of the prepared Fe3O4/Bi2O2(OH)(NO3) for degradation of rhodamine B (RhB) dye under natural sunlight irradiation was investigated. The 3%Fe3O4/Bi2O2(OH)(NO3) photocatalyst, comprising 3 ​mol% of Fe3O4, showed high efficiency (about 98.7%) after 120 ​min of photo illumination. The photogenerated holes played a prominent role in the photodegradation of the dye. The present finding demonstrated the enhancement of photocatalytic performance using the fabrication of a novel, sunlight-active photocatalyst with a low electron-hole recombination rate at the interface.

Hollow-structured Pd/TiO2 as a dual functional photocatalyst for methyl orange oxidation and selective reduction of nitrate into nitrogen

Nitrate pollution in wastewater has posed a threat to human health and the environment. Photocatalytic reduction is a promising technology to remove nitrate due to its high adaptability, low cost, and high efficiency. However, there is a great challenge to design photocatalyst with high nitrate reduction and high selectivity of nitrogen (N2) yield. In this study, a novel hollow-structured Pd/TiO2 (PHT1) photocatalyst is synthesized with large specific surface area (SBET) and pore volume, strong UV adsorption, high reduction potential than nitrate to nitrite, high charge transfer rate, and low electron-hole recombination rate. PHT1 exhibits a superior photocatalytic activity on the removal of methyl orange and nitrate. In addition, PHT1 exhibits high N2 selectivity (>95 %). A lower pH can promote the reduction of nitrate and the selectivity of N2 by PHT1. Electrons (e-) and CO2– are the main active species for nitrate reduction with OH as auxiliary radicals. Three main pathways for nitrate reduction are proposed: i) the reaction with formic acid under acidic conditions; ii) the reduction by electrons and the loaded Pd of photocatalyst to capture electrons to inhibit electron-hole recombination; iii) the reduction by CO2– generated from formic acid oxidation by OH.

Theoretical study on the photocatalytic potential of BSe nanotubes for water splitting under visible light

Photocatalytic splitting of water has been a useful tool in recent years for solving the world's energy and environmental problems. However, the wide band gap and low carrier mobility of traditional photocatalysts are the reasons that limit their wide application. In this work, the structure, and optical properties of BSe nanotubes are studied for the first time based on density functional theory.The results show that single-walled BSe nanotubes (SW BSe NTs) not only have a stable structure but can also extend the ultraviolet light absorption range of the BSe monolayer to the visible light range. Significantly, the SW BSe NT has excellent photoreduction ability, low electron-hole recombination rate, and high hole carrier mobility (∼103 cm2V−1s−1). Under uniaxial strain, the SW BSe NT exhibits a direct-indirect band gap transition. Furthermore, the electronic structure of double-walled BSe nanotubes facilitates charge separation and has a wider range of light absorption. Unluckily, its lower band edge position prevents it from having an overall photocatalytic decomposition capability. Our results show that SW BSe NTs have potential applications in visible light-driven photocatalytic water splitting.

Boosting charge separation of CeO2–MnO2 nanoflake with heterojunctions for enhanced photocatalytic hydrogen generation

Herein, we report about the synthesis and tuning of a highly conductive CeO2–MnO2 composite with cubic fluorite CeO2 and tetragonal MnO2 for industrial photocatalytic hydrogen generation. Specific nanoflake morphology and enhanced electron transfer during photo-excitation of the composite are tailored by fine tuning of the composition and synthesis parameters. The tuned composite (1:1 CeO2–MnO2) with heterojunctions results in the enhanced photoresponse characteristics due to low band gap energy (2.4 eV), low electron-hole recombination rate, increased electron lifetime (7.92 ns) and efficient electron transfer ability. The composite exhibits enhanced rate of photocatalytic hydrogen generation (540 μmol h−1) under visible light irradiation during long term analysis with excellent stability and reusability, competent to commercial grade photocatalysts.

Janus Ga2SSe nanotubes as efficient photocatalyst for overall water splitting

Using sunlight to decompose water into hydrogen and oxygen is one of the most important ways to solve the current global environmental issues and energy problems. In this paper, we use density functional theory to predict the photocatalytic performance of Janus Ga2SSe nanotubes (JGSSe NTs) for the first time. The result shows that the small formation energy and strain energy ensure the stability of the nanotubes. Compared with monolayers, the visible light absorption range of JGSSe NTs is wider, and the large radius (>26.60 A) nanotubes all meet the hydrolysis potential. Surprisingly, the hole mobility of JGSSe NT was estimated to be as high as 2.89 × 104 cm2 V−1 S−1. In conclusion, JGSSe nanotubes are expected to be an excellent photocatalyst due to their low electron–hole recombination rate, high hole mobility, solar absorption in the visible light range, and good oxidation capacity. In addition, the nanotube band gap can be effectively regulated by applying strain. It is hoped that our research will provide meaningful progress in the development of novel and efficient photocatalysts. We hope that our research will provide a possible way to develop novel and efficient photocatalysts.

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.