Excellent Photocatalytic Activity Research Articles

Ni Nanoparticles Supported Over Triazine Based Porous Organic Polymer for Selective CO2 Photo‐Reduction to Methanol

AbstractPorous organic polymers (POPs) have attracted substantial attentions over the years due to their exceptionally high specific surface areas, high chemical stability of the organic network and ease of surface functionalization with the desired organic groups. In this work, a triazine based POP (TrzPOP) was synthesized through Schiff base polycondensation reaction between a tetramine bearing triazine rings and phenolic–OH group rich dialdehyde. Ni nanoparticles (NiNP) synthesized independently were immobilized over TrzPOP to obtain the NiNP@TrzPOP composite catalyst. This TrzPOP possesses a high BET surface area of 1494 m2 g−1 and low band gap, which facilitates its role as visible light absorbent. NiNP@TrzPOP with N‐rich surfaces and phenolic–OH moieties displayed excellent photocatalytic activity in the CO2 photoreduction under mild reaction conditions. NiNP@TrzPOP composite selectively reduces CO2 to methanol. The turn over number (TON) for this photoreduction of CO2 under optimized reaction conditions is 270, which is considerably high comparing to other reported photocatalytic systems. Moreover, NiNP@TrzPOP composite catalytic system showed high recycling efficiency without noticeable decrease in its performance over five consecutive reaction cycles, suggesting its huge potential for large‐scale methanol synthesis from the renewable carbon source.

Pt nanoclusters modified porous g-C3N4 nanosheets to significantly enhance hydrogen production by photocatalytic water reforming of methanol

For the use of green hydrogen energy, it is crucial to have efficient photocatalytic activity for hydrogen generation by water reforming of methanol under mild conditions. Much attention has been paid to g-C3N4 as a promising photocatalyst for the generation of hydrogen. To improve the separation of photogenerated charge, porous nanosheet g-C3N4 was modified with Pt nanoclusters (Pt/g-C3N4) through impregnation and following photo-induced reduction. This catalyst showed excellent photocatalytic activity of water reforming of methanol for hydrogen production with a 17.12 mmol·g−1·h−1 rate at room temperature, which was 311 times higher than that of the unmodified g-C3N4. The strong interactions of Pt–N in Pt/g-C3N4 constructed effective electron transfer channels to promote the separation of photo-generated electrons and holes effectively. In addition, in-situ infrared spectroscopy was used to investigate the intermediates of the hydrogen production reaction, which proved that methanol and water eventually turn into H2 and CO2via formaldehyde and formate. This study provides insights for understanding the photocatalytic hydrogen production in the water reforming of methanol.

Remarkably enhanced hydrogen evolution of g-C3N4 nanosheet under simulated sunlight via AgPt alloy co-catalyst with low amount of Pt

The development of low-cost co-catalysts matched with proper photocatalysts to enhance the photocatalytic hydrogen evolution performance is highly demanded. Herein, the AgPt bimetallic alloy nanoparticles with small amounts of Pt were decorated on g-C3N4 nanosheets (AP-CN) via the NaBH4 reduction method, which were further used as catalysts towards photocatalytic hydrogen evolution from water under AM1.5 irradiation. Compared to mono-metallic co-catalysts, bimetallic AgPt alloy nanoparticles exhibited excellent co-catalytic performance. The optimum AP-CN photocatalyst with 0.5 wt% Pt exhibited photocatalytic hydrogen evolution rate of 3507.89 μmol g−1·h−1, which even surpassed that of the commonly-used photocatalyst 1.0 wt% Pt in-situ photo-deposited on g-C3N4. Meanwhile, the AP-CN showed excellent photocatalytic activity and durability after four experimental cycles. The enhanced activity and stability could be attributed to the synergistic effect between plasmonic metal Ag and Pt, which promoted the transfer and separation of photoinduced charge carriers. Besides, the theoretical results based on DFT calculation also verified that AgPt alloys have better performance of desorbing hydrogen and adsorbing H atoms. This work provides a feasible idea for the development of inexpensive and efficient bimetallic co-catalysts for photocatalytic hydrogen production through water splitting.

Synthesis of S-type heterostructure π-COF for photocatalytic tetracycline degradation

Photocatalytic oxidation is a promising technology for wastewater treatment. It is a more desirable method than other conventional wastewater treatment approaches due to its low cost, environmental friendly, and capability to completely degrade pollutants into environmentally safe products under appropriate conditions. Among some photocatalysts, covalent organic frameworks with high photoactivity are recognized as stable and feasible materials for this purpose. In this work, highly-effective photocatalyst of S-type heterostructure π-COF was successfully synthesized by using ultrasonic delamination treatment sp2c-COF nanosheets (sp2c-NS) and py-NH2-COF nanosheets (Py-NH2-NS) via a secondary solvent heating method. The preparation was initiated by synthesizing sp2c-COF and py-NH2-COF successfully adopting pyrene templates by solvothermal method. The study focused on physicochemical characterization and photocatalytic activity of π-COF. The photocatalytic ability of π-COF was carried out to degrade tetracycline under visible light. The results indicate that π-COF not only shows excellent photocatalytic activity for tetracycline degradation of 94.8 % at 90 min under visible light illumination, but also has good photocatalytic degradation performance at wide initial pH values, coexisting ions, and actual water sources. Surprisingly, it has excellent stability and recyclability, it can afford high oxidative degradation (87.3 %) even after 5 successive recycles. The degradation mechanism was discussed by various methods such as active species trapping experiment, electron paramagnetic resonance determination and related electrochemical analysis. In addition, the main degradation intermediate products and the possible pathways of TC degradation were detected and proposed according to LC − MS technology. This work provided a new strategy for the preparation of hetero-structured COF which could be served as an advantageous photocatalyst for the treatment of pharmaceutical industry wastewater.

One-Dimensional Shaving-like BiVO4 Nanobelts: Synthesis, Characterization and Photocatalytic Activity with Methylene Blue

One-dimensional shaving-like BiVO4 nanobelts were successfully synthesized via the oxide hydrothermal method (OHS), using V2O5 and Bi2O3 as raw materials and PEG 10000 (polyethylene glycol 10000) as a template. Multiple techniques, including XRD, SEM, TEM, HRTEM, UV–Vis, XPS, and photoelectrochemical measurements, were applied to characterize the obtained materials. The thickness of the BiVO4 nanobelt was approximately 10 nm, while the width was approximately 500 nm. EIS results showed that visible-light illumination caused the photogenerated charge of the BiVO4 nanobelts to have a faster transfer and a higher separation efficiency. Photocatalytic experiments indicated that with BiVO4 nanobelts as a catalyst, the degradation rate of MB (methylene blue) was close to 92.4%, and it disintegrated after two hours. Moreover, the pseudo-first-order kinetic model can be used to describe the photodecomposition reaction of MB catalysed by BiVO4 nanobelts. And this excellent photocatalytic activity of the shaving-like BiVO4 nanobelts may be related to their special morphology, narrow band gap (~2.19 eV), faster transfer and the separation efficiency of the photogenerated charge, leading to strong absorption in the visible region and improving the separation of the photogenerated electron–hole pairs. These novel monoclinic BiVO4 nanobelts exhibited great photocatalytic activity and are thus a promising candidate for application in visible-light-responsive photocatalysts.

Facile synthesis of silver chloride-polyaniline nanocomposites and its photocatalytic activity for the degradation of methylene blue

Herein, we report a green and an effective strategy for the synthesis of polyaniline-silver chloride (AgCl@PANI) nanocomposites by using facile in-situ chemical oxidative polymerization method in the presence of as-synthesized silver nanoparticles (Ag NPs) for the study of their photocatalytic activity towards the photodegradation of methylene blue (MB) under UV irradiation. The contents of Ag NPs varied from 2% to 6% during polymerization reaction to get AgCl@PANI nanocomposites. These synthesized polymer nanocomposites were characterized for their structural and optical properties, thermal stability, dc conductivity and photocatalytic activity by FT-IR spectroscopy, XRD, UV–Vis spectroscopy, TGA, SEM, standard four probe method and the photodegradation activity of MB, respectively. XRD analysis confirm the successful formation of AgCl@PANI nanocomposites without the presence of additional phases. TGA shows that AgCl@PANI nanocomposites have excellent thermal stability due to the barrier effect of AgCl moieties bounded with in the polymer chain and the strong physiochemical interactions between PANI and AgCl as inferred from FT-IR and UV–vis analysis. Under UV irradiation, the AgCl@PANI nanocomposite, with 4 wt% of Ag NPs (AgCl@PANI-4%), demonstrated excellent photocatalytic activity for MB degradation with the photodegradation percentage of ∼ 99 % in 20 min. The experimental findings illustrate that the superior photocatalytic activity of AgCl@PANI nanocomposites is owing to incorporation of AgCl moieties in the polymer structure, less needed energy for the formation of electron-hole pairs in the quinoid ring of PANI in the UV-region, enhanced light absorption owing to smaller grain size morphology, high surface area of the nanocomposite and high electrical conductivity (128 mS.cm−2). These results suggest the potential of these synthesized conjugated polymer-based nanocomposites as a photocatalyst for cost-effective and efficient wastewater treatment for the industrial applications.

Construction of BiOCl/Bi2WO6 Z-scheme heterojunction with close interfacial contact using CNT as electron medium

Enhancing carrier separation capabilities and extending the visible light absorption range are essential for overcoming the low photocatalytic performance of single semiconductors. In this study, by using hydrothermal and ion-exchange methods, a series of Z-scheme heterojunction BiOCl/CNT/Bi2WO6 photocatalysts with visible light response were successfully constructed by using carbon nanotubes (CNT) as an electronic medium. Under visible light irradiation, the photocatalytic performances of the samples were evaluated by the degradation of tetracycline and ciprofloxacin. The results shown that the BiOCl/CNT/Bi2WO6 heterojunction photocatalysts possessed excellent photocatalytic activity, and the kinetics reaction models of the photocatalysts followed pseudo-first-order kinetics. This excellent photocatalytic performance may be due to the acceleration of photogenerated carrier separation due to the formation of heterojunction and the CNT as an electronic medium, as well as the close contact interface between the BiOCl/Bi2WO6 heterojunction, which shortened the carrier migration path. The charge transfer mechanism in the BiOCl/CNT/Bi2WO6 Z-scheme heterojunction composites was proposed based on the results of trapping experiments, in-situ XPS and SPV. Furthermore, three degradation pathways were discussed, and toxicity assessments of intermediates showed that the toxicity after photocatalytic degradation decreased. This study could bring light on the development of promising and novel CNT-mediated Z-scheme heterojunction photocatalysts for pollutant degradation.

Aluminum-Porphyrin Metal-Organic Frameworks for Visible-Light Photocatalytic and Sonophotocatalytic Cr(VI) Reduction.

In this study, four isostructural aluminum-based porphyrin metal-organic frameworks [Al-TCPP(M), M = H2 and Zn] with different morphologies and sizes were synthesized by the hydrothermal method. By adjusting the hydrothermal reaction time and the types of porphyrin ligands, Al-TCPP(M) MOFs exhibited diverse morphologies including tetragonal, rectangular, and carambola-like phase. In view of the introduction of porphyrin ligands and the strong coordination effect of Al-O units, Al-TCPP(M) MOFs exhibited good chemical stability, broad visible light harvesting capability, and fast photogenerated charge response. Four Al-TCPP(M) MOFs exhibited excellent photocatalytic activities for Cr(VI) in aqueous solution. Notably, the regulation to the nanoscale carambola-like morphology of Al-TCPP MOFs and metallization of the porphyrin ligand promoted the Cr(VI) photoreduction reaction where the catalytic activity of metallic carambola-like Al-TCPP increased 1.7 times compared to that of nonmetallic tetragonal MOFs. With the assistance of sonophotocatalysis, the Cr(VI) average reduction rates reached 0.658, 0.542, 0.785, and 0.629 mg·L-1·min-1 for Al-TCPP(H2)-24h, Al-TCPP(H2)-72h, Al-TCPP(Zn)-24h, and Al-TCPP(Zn)-72h, which are 1.2-1.4 times higher than that of photocatalysis. UV-vis absorption spectroscopy, electronic spin resonance, and fluorescence spectroscopy experiments demonstrated that the synergistic effect of photochemistry and sonochemistry promoted the transfer of photogenerated electrons from Al-TCPP(M) to Cr(VI), thus enhancing the catalytic activity. The combination of the sonophotocatalytic technology with aluminum-porphyrin MOFs may become an effective strategy to improve MOF-based photocatalytic systems.

NH<sub>2</sub>-modification Copper Metal-organic Framework as a Sunlight Photocatalyst for the Removal of Organic Dyes from Aqueous Solution

Dyes present in wastewater pose a threat to aquatic organisms and cannot be effectively eliminated by conventional biochemical treatment methods. As an alternative, the photocatalytic decolorization of dyes has emerged as a cost-effective and environmentally friendly approach. Two 1,3,5-benzenetricarboxylate (BTC)-based metal-organic frameworks (MOFs), CuBTC and CuBTC-NH2, were synthesized and used for the removal of two anionic dyes, namely Reactive Blue 171 and Acid Blue 1, from wastewater under sunlight irradiation. The structural and morphological characteristics of the MOFs were identified using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Compared to CuBTC, CuBTC-NH2 exhibited excellent photocatalytic activity. The successful degradation of 90% of the dyes was observed within 24 h of sunlight exposure using CuBTC-NH2, while only 70% degradation was achieved with CuBTC. The weak basic nature of the dye wastewater (pH 8-10) was found to facilitate the degradation process. CuBTC-NH2 was not only efficient in the removal of dyes but could also be recycled and reused for at least five cycles. In the process of photocatalytic degradation, the diazo bond of dyes in ortho-position to the amino substitution on the aromatic ring was attacked first. These results provide insights into the design of MOF catalysts for dye removal under visible-light irradiation.

Non-iridescent Structurally Colored Pigments Based on CB@SiO2@TiO2 Core-Bishell Nanospheres with Enhanced Color Stability and Excellent Photocatalytic Activity.

In recent years, artificial amorphous photonic structure (APS) materials with high color saturation and angle independence have been competitively reported. However, there is a lack of research into their functionalization and application in practical environments. Here, with practical applications in mind, we prepared APS pigments based on CB@SiO2@TiO2 core-bishell nanospheres and demonstrated high color saturation, enhanced color stability, and excellent photocatalytic activity. SiO2 effectively protected the carbon black particles from ablation during the calcination process. Paints composed of ethanol, ethyl cellulose (EC), and pigments could be spray-coated on any substrate to prepare a structurally colored coating without limitation. The coatings show good mechanical stability and photothermal stability. The color of the structurally colored pigments can be easily changed by adjusting the sizes of the CB@SiO2@TiO2 nanospheres. The photocatalytic activity of the pigments on formaldehyde (HCHO) and methylene blue (MB) solution and reaction kinetics of their degradation were studied by experiment. The results showed that the photocatalytic activity of the pigments increased with the increase of the TiO2 loading, and the degradation rate of HCHO reached 96.7% for 3 h and that of MB reached 97.9% for 60 min when the TiO2 shell thickness was 40 nm. The structurally colored pigments based on CB@SiO2@TiO2 nanospheres effectively solve the environmental problems caused by the application of pigments and have a promising future in the fields of color decoration, display, and painting.

Monodispersed Ag nanoparticles deposited on Ni-based coordination polymer composite with enhanced photocatalytic degradation for bisphenol A

Exploring effective methods to improve photoresponse and charge separation efficiency is the key to preparing high-performance photocatalysts. A novel Ni-based coordination polymer, namely {[Ni(TIPA)2]·2Ac·6 H2O}n (Ni-TIPA), was designed and synthesized hydrothermally using the ligand tri-(4-imidazole phenyl) amine (TIPA). The metal-to-ligand charge transfer (MLCT) of Ni-TIPA is visually demonstrated by theoretical calculations as the key to enhanced charge separation efficiency. A series of novel silver-deposited Ni-TIPA composites (Ag@Ni-TIPA-X, X = 1, 2, 3) and excellent light-driven photocatalytic activity were prepared using a simple photoreduction method at room temperature. The prepared Ag@Ni-TIPA-2 composite had excellent photocatalytic performance for degrading bisphenol A (BPA) under ultraviolet light irradiation. The excellent photocatalytic performance might be attributed to MLCT and the surface plasmon resonance (SPR) of Ag nanoparticles, which improved hole-electron separation capability, and the formation of Schottky junctions. The intermediates in the BPA degradation process were further predicted and analyzed by electrostatic potential (ESP), orbital-weighted dual descriptor (ODD), and liquid chromatography-mass spectrometry (LC-MS) technologies, and the possible degradation mechanisms were deduced deeply. The work as a new reference might be provided for the efficient optimization of photocatalysts for BPA degradation.

A simple photocatalytic assisted strategy by MIL-100 (Fe) for fabrication of polymer based on H-bonding as filtrate reducer to resist salt and temperature in ultra-deep wells

Improving the performance of water-based drilling fluids for high temperature, salt and calcium resistance in the exploration of deep and ultra-deep wells is a matter of great urgency. In this study, MIL-100 (Fe) nanosphere catalyst with regular shape, uniform size and good monodispersity is prepared ahead of time. XRD, SEM and BET tests indicates that the MIL-100 (Fe) owning large specific surface areas, adjustable pore sizes and high porosity can display to be a photocatalyst. Based on the excellent photocatalytic activity under visible light, a new one-pot method strategy was supposed to achieve the graft modification on N atom in acrylamide using aziridine, and obtained the multi-amine allyl monomer. Finally, the poly (AM/AMPS/PSMM) (PAAP) filtrate reducer with significant hydrogen bonding effect was successfully synthesized by free radical copolymerization with acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and the pre-synthesized multi-amine allyl monomer. Due to the three dimensional hydrogen bonding interaction and resulted supramolecular association structure, the PAAP-based drilling fluids exhibit outstanding rheological and filtration properties even after aging at high temperatures and high salinity. The filtration volume after aging at 180 °C for 16 h is only 6.0 mL, meanwhile, the 20 wt% NaCl and 1.5 wt% CaCl2 copolymer base slurry aged at 180 °C both show the satisfactory filtration loss and offering performance higher than commercial filtrate reducers. Specifically, after aging at 180 °C, the filtration losses of DSP-1/BM and DSP-2/BM were 19.8 and 37.2 mL with 20 wt% NaCl contamination, respectively, while the filtration loss of PAAP was only 10.8 mL. Even under both 1.5 wt% CaCl2 contamination and 180 °C aging, the filtration loss of PAAP was only 11.0 mL, whereas the filtration loss of DSP-1 and DSP-2 reached 26.0 and 20.0 mL. Finally, the filtration control mechanism of poly (AM/AMPS/PSMM) was proposed via XPS test, hydrogen bonding analysis, filter cake morphologies observation by SEM and particle size distribution measurement.

Effective photocatalytic inactivation of Microcystis aeruginosa by Ag3VO4/BiVO4 heterojunction under visible light

In recent years, photocatalytic technology has been increasingly used for the treatment of algal blooms in water bodies due to its high efficiency and environmental advantages. However, conventional semiconductor materials suffer from high electron-hole recombination rate, low carrier mobility and weak surface adsorption ability, which made their photocatalytic performance limited. Therefore, the photocatalytic performance of the composites can be improved by coupling another semiconductor material to form a heterojunction to accelerate electron transfer. In this study, a novel composite Ag3VO4/BiVO4 (ABV) photocatalyst was successfully prepared by in-situ deposition method for the photocatalytic inactivation of Microcystis aeruginosa (M. aeruginosa) under visible light. The photocatalyst showed excellent photocatalytic activity, and the degradation rate of M. aeruginosa chlorophyll a was up to 99.8% within 4 h under visible light. During the photocatalytic degradation, the morphology of algae cells, the permeability of cell membrane, the organic matter inside and outside the cells, the antioxidant system and the soluble protein were seriously damaged. Moreover, three cycle experiments showed that the prepared ABV photocatalyst had high reusability. Finally, a possible mechanism of M. aeruginosa inactivation was proposed. In general, the synthesized ABV photocatalyst can effectively inactivate cyanobacteria under visible light and provided a new method for M. aeruginosa removal in water.

ZnIn2S4/TiO2 photocatalyst for CO2 photoreduction: Advancing sustainable energy conversion to renewable solar fuels

The rapid increase in CO2 concentration in the atmosphere raised global climate challenges, which creates attention for the researcher to mitigate CO2 from the atmosphere so that the environment can be sustained for generations. From the photocatalysis perspective, reducing CO2 into carbon monoxide (CO) and methane (CH4) is a promising pathway for sustainable solar fuel production. Here, we fabricated a heterojunction nanocomposite photocatalyst of ZnIn2S4 and TiO2. The photocatalyst was highly efficient for CO2 reduction with 1754 and 481 μmol/g yields of CO and CH4, respectively. The photocatalyst had excellent photocatalytic activity and was stable for five consecutive experiments without significant activity loss. The potential of ZnIn2S4/TiO2 photocatalyst to revolutionize carbon monoxide production for various applications underscores its significance in advancing sustainable carbon mitigation strategies.

Luminescence and photocatalytic properties of bifunctional materials CaTi2O4(OH)2:Eu3+ and [CaTi2O4(OH)2–CaTiO3]:Eu3+

CaTi2O4(OH)2:Eu3+, CaTiO3:Eu3+ and [CaTi2O4(OH)2–CaTiO3]:Eu3+ were synthesized by a solvothermal method without the help of templates or surfactants. And their structures, luminescence properties, and photocatalytic properties were systematically studied. The RIR (reference intensity ratio) data of CaTi2O4(OH)2 were first investigated via X-ray diffraction (XRD), thus the ratios of each phase in the (m%CaTi2O4(OH)2-n%CaTiO3):3%Eu3+ biphasic mixture was determined. The bandgap value of CaTi2O4(OH)2:3%Eu3+ is 0.28 eV less than that of CaTiO3:3%Eu3+. The specific surface area of CaTi2O4(OH)2 is 8.2 times larger than that of CaTiO3. Compared with CaTiO3:Eu3+, the CaTi2O4(OH)2:Eu3+ showed stronger luminescence intensity. The Judd-Ofelt theory analysis show that the Eu3+ ions in CaTi2O4(OH)2:Eu3+ have low local symmetry, high Eu–O bonds covalence and low ligands electron density. The photocatalytic properties of CaTi2O4(OH)2:y%Eu3+, CaTiO3:x%Eu3+ and [62.2%CaTi2O4(OH)2-37.8%CaTiO3]:3% Eu3+ were comparatively studied in detail. The band-gap value of [62.2 % CaTi2O4(OH)2–37.8%CaTiO3]:3%Eu3+ is significantly reduced due to the presence of heterojunctions compared to CaTi2O4(OH)2:y%Eu3+ and CaTiO3: x%Eu3+. The built-in electric potential at heterojunction interface will guide electrons and holes to move in opposite directions, therefore [CaTi2O4(OH)2–CaTiO3]:Eu3+ has excellent photocatalytic activity.

In situ co-crystallization synthesis of the direct Z-scheme Bi5O7I/Bi2SiO5 heterojunction for enhanced photocatalytic rhodamine B and ciprofloxacin degradation

Semiconductor photocatalysis has driven considerable interests for its desirable potential to tackle the worldwide energy shortage and environmental pollution. In this paper, a novel Bi5O7I/Bi2SiO5 Z-scheme heterojunction photocatalyst was in situ synthesized via a co-crystallization process and partial anion exchange strategy. The XRD and FT-IR pattern validated the successful preparation of the heterojunction. The optimal Bi5O7I/Bi2SiO5 heterojunction displayed an excellent photocatalytic activity towards the ciprofloxacin under the simulated solar light, and the rate constant (0.46021 h−1) was 2 and 7.8 times higher than that of pure BiOI (0.22967 h−1) and Bi2SiO5 (0.05877 h−1). Similarly, the degradation efficiency on rhodamine B (RhB) reached 94%, which was much higher than that of the single photocatalysis. The enhanced photocatalytic performance of the heterojunction photocatalyst could be attributed to the formation of the direct Z-scheme heterojunction between the Bi5O7I and Bi2SiO5, which was favorable for retarding the recombination of photoinduced electron-hole pairs. Moreover, the bacteriostatic activity testing illustrated the toxicity of drug solutions decreased sharply after the photocatalytic degradation with the Bi5O7I/Bi2SiO5-3. The ESR characterization analysis and the free radical trapping experiments synergistically determined the Z-scheme electron transfer path of the heterojunction. The possible photocatalytic mechanism of Bi5O7I/Bi2SiO5 heterojunction was proposed. Overall, the well-designed Bi5O7I/Bi2SiO5 heterojunction depicted great practical promise in efficient treatment of organic pollutants.

Supramolecularly engineered S-scheme SubPc-Br/MoS2 photocatalyst nanosheets for enhanced photocatalytic degradation of antibiotics

Developing a simple, low-cost, high-yield, and controllable strategy for preparing various functionalized MoS2-based composite materials remains a challenge. This study innovatively utilizes boron subphthalocyanine bromide (SubPc-Br) as a photosensitizer, which self-assembles on MoS2 via intermolecular π-π stacking, creating a SubPc-Br/MoS2 organic–inorganic semiconductor system. This addresses a research gap, employing subphthalocyanines as MoS2 sensitizers. The SubPc-Br/MoS2 heterojunction exhibited excellent photocatalytic activity for the degradation of antibiotics in water under solar irradiation. The rate constants for the photocatalytic degradation of CTC and CIP by SubPc-Br/MoS2 were 4.66 and 5.93 times higher than those of pristine MoS2, respectively. The significant improvement in photocatalytic performance is attributed to the efficient charge separation and transfer induced by the unique S-Scheme charge transfer mechanism, which has been verified by different theoretical and experimental results. We demonstrate that the photochemical activity of O2 molecules adsorbed on MoS2(100) is site-sensitive, with O2 preferentially adsorbing on the Mid-site location with higher electron transport capability. This study provides a new perspective for enhancing photocatalytic performance by constructing an artificial photosynthetic system with an S-scheme heterojunction.

Construction of ZnxCdyS with a 3D Hierarchical Structure for Enhanced Photocatalytic Hydrogen Production from Water Splitting.

The ZnxCdyS has been proven to have unique photoelectric properties, but its synthesis method and photocatalytic water cracking performance need to be further improved. In this paper, Cd-MOF@ZIF-8 with a MOF-on-MOF (MOF = metal-organic framework) structure was prepared by a simple ion adsorption method. Then, a CdS/ZnxCdyS heterojunction with a 3D hierarchical structure was formed by solvothermal sulfidation. The prepared catalysts with different Zn/Cd ratios show an improved hydrogen production performance for photocatalytic water splitting, and the hydrogen evolution rate of Zn1Cd1S can reach up to 29.2 mmol·g-1·h-1. The excellent photocatalytic activity not only benefits from ZnxCdyS strong light conversion ability but also is closely related to the hierarchical structure and large specific surface area. A type II heterojunction also plays an important role in the spatial separation of photogenerated carriers. This paper provides a simple and feasible idea for the synthesis of a photocatalyst with a large specific surface area using a MOF-on-MOF synthesis strategy.

Preparation and Photocatalytic Properties of SnO2/C/PPy Composites

SnO2/C(Carbon)/PPy composites have been prepared by in situ polymerization using SnO2/C nanomaterials as the matrix. The structures and properties of as-synthesized samples were characterized by XRD, FT-IR, XPS, BET, SEM and TEM. Meanwhile, the photocatalytic reaction mechanism of SnO2/C/PPy composite for degradation of Rhodamine B (RhB) was analyzed. The photocatalytic tests indicated that the SnO2/C/PPy composites have excellent photocatalytic activity for RhB degradation under visible light irradiation and the RhB can be degraded to 90% within 20 min. The photocatalytic activity is still outstanding after five cycles and as-synthesized samples have emerged as powerful foundation for further industrial application.

A new 3D supramolecular Cu(ii) framework: Crystal structure and photocatalytic characteristics

Abstract Reported here is a new Cu(ii) compound with the formula of {Cu4(μ 2-Cl)6(μ 4-O)(4-NH2-py)4} n (1, 4-NH2-py = 4-amino-pyridine). The analysis of X-ray diffraction shows that the complex 1 indicates a 0D separated skeleton with {Cu4(μ 2-Cl)6(μ 4-O)} tetranuclear cluster. The interactions of H-bond between the amino groups and μ 2-Cl anions from adjacent 0D cluster further extended this 0D cluster into a 3D supramolecular framework. In addition, this compound has excellent photocatalytic activities for the degradation of methyl blue under UV radiation. The cyclic testing results indicate that complex 1 exhibits good recyclability, as it can be repeated for as many as five cycles with no noticeable loss of performance, revealing its potential application in pollutant degradation within the environmental field.