Photocatalytic Performance Research Articles

Orientation-Dependent Photocatalysis of Imine-Linked Covalent Organic Frameworks Based on Thienothiophenes for Oxidation of Amines to Imines.

Toward visible light photocatalysis, covalent organic frameworks (COFs) have recently garnered growing attention. The effect of different orientations of imine of imine-linked COFs on photocatalysis should be elucidated. Here, two COFs are developed with 2,5-diphenylthieno[3,2-b]thiophene (DPTT) and 1,3,6,8-tetraphenylpyrene (Py) linked by imine, affording DPTT-Py-COF and Py-DPTT-COF, respectively. Distinctly, DPTT-Py-COF and Py-DPTT-COF have high crystallinity and porosity, paving the way to highly efficient photocatalysis. Theoretical calculations demonstrate that both DPTT-Py-COF and Py-DPTT-COF are of similar bandgaps but of varied energy positions due to the different orientations of imine. Besides, characterizations disclose that DPTT-Py-COF delivers more enhanced charge separation and transfer than Py-DPTT-COF. Probed by the oxidation of amine to imine, DPTT-Py-COF exhibits a blue light photocatalytic performance superior to that of Py-DPTT-COF. DPTT-Py-COF, a highly recyclable photocatalyst, enables the oxidation of various amines to imines with oxygen. This work highlights that tuning the microenvironment of COFs unravels tenable performances in photocatalysis.

Enhancement of photocatalytic degradation of ciprofloxacin via constructing conductive matrix

The application of heterogeneous photocatalysts is severely limited by the high charge transfer resistance (Rct). BiVO4/g-C3N4 photocatalysts were prepared and loaded on the conductive matrix material carbon paper (CP) to reduce electron transfer resistance and improve the photocatalytic performance. The Rct of BiVO4/g-C3N4@CP was remarkedly reduced by 94.3 % compared to the photocatalysts on the oil paper (BiVO4/g-C3N4@OP), while the photocurrent density increased by 5.5 times. The utilization efficiency of light energy and separation of photoelectrons and holes were improved with CP due to its ability to facilitate long-distance transfer of photoelectrons. Consequently, the photocatalytic degradation performance of BiVO4/g-C3N4@CP was enhanced by a 26.1 % improvement in ciprofloxacin (CIP) degradation efficiency. Quenching experiment, LC-MS analysis and DFT calculation revealed that piperazine ring opening and C-F cleavage were the major pathways for CIP degradation with BiVO4/g-C3N4@CP.

A Reactor based on P‐N Heterojunction of Polypyrrole and Porous Silicon for Photocatalytic and Electro‐assisted Photocatalytic Performance

AbstractIn this work, a photoelectrochemical reactor with an anode based on hybrid structure between conducting polymer polypyrrole (PPy) and porous silicon (PSi) was fabricated and utilized to evaluate the photocatalysis and electro‐assisted photocatalysis for degradation of rhodamine B (RhB) solution. The PSi was made of n‐type silicon single‐crystal wafer by the metal‐assisted chemical etching (MACE). The anode PPy/PSi formed following a polymerization of the PPy on the PSi from the vapour‐phase route using oxidant FeCl3. Typical material characterizations of the PPy, PSi and PPy/PSi were investigated via scanning electron microscope (SEM), and spectroscopies of Fourier‐transform infrared (FTIR), Raman scattering and UV‐vis. Under visible light radiation (halogen light with the wavelength region of 400–700 nm), photocatalytic and electro‐assisted photocatalytic processes of the reactor were conducted by degradation of the RhB solution. A heterojunction (p‐n) of the PPy/PSi was proposed to explain the efficient catalytic performance of the reactor.

Ag2Se nanoparticles anchored on S-g-C3N4 nanosheets towards efficient photocatalytic tetracycline hydrochloride removal and H2 generation

To improve the stability of Ag based co-catalysts and to increase the photocatalytic performance of graphitic carbon nitride (g-C3N4), Ag2Se nanoparticles were grown onto superior thin sulfur-doped g-C3N4 nanosheets which was fabricated via two-step thermal polymerization at high temperature. Ultrathin S-doped g-C3N4 nanosheets were prepared via two-step thermal polymerization using melamine and thiourea. The ratios of Ag2Se were adjusted to fabricate a series of Ag2Se/S-g-C3N4 (Ag2Se/SCN) composite samples by controlled solvothermal synthesis. S-doping plays an important role in mono-dispersion of Ag2Se nanoparticles on S-g-C3N4 nanosheets because of the control of growth sites. The photocatalytic removal of tetracycline hydrochloride test indicates that sample Ag2Se/SCN-3 with Ag2Se loading of 3 % reveals the best removal effect, in which tetracycline hydrochloride of 60 % is removed within 60 min. Photocatalytic hydrogen generation test results without co-catalyst addition demonstrate that sample Ag2Se/SCN-3 exhibits the best H2 evolution rate of 2116.35 μmol·g−1·h−1, which is 3.8 times of that of pure carbon nitride. The photocatalytic mechanism tests suggest that Schottky heterojunctions are formed in the Ag2Se/S-g-C3N4 composites. The formation of Schottky heterojunctions improved the separation efficiency of photogenerated charge carriers. The incorporation of Ag2Se nanoparticles (as the co-catalyst) on S-g-C3N4 nanosheets is the key for drastically improving the photocatalytic performance and eliminating the use of Pt co-catalyst during the photocatalytic processes.

A Comprehensive Comparison of the Structural, Ferroelectric, Energy Storage, and Photocatalytic Properties of Chemical Composition-Tailored Perovskite Ceramics

Abstract This article reports on the structural, ferroelectric, energy density, and photocatalytic properties of (Pb0.50Ba0.35Ca0.15)(Fe0.25Nb0.25Ti0.50)O3 [PBCTO] and (Pb0.50Ba0.50)(Fe0.25Nb0.25Zr0.1Ti0.40)O3 [PBZTO] ceramics synthesized by the solid synthesis route. X-ray diffraction and Raman spectra confirmed peaks corresponding to perovskite crystalline structure with tetragonal phase for both PBCTO and PBZTO ceramics. Slim ferroelectric hysteresis was observed in polarization-electric field measurements. Remnant polarization (Pr), and coercive field (Ec) values are ~3.63 µC/cm2, ~25.4 kV/cm, and ~1.39 µC/cm2 and 17.9kV/cm for PBCTO and PBZTO, respectively. Energy densities were obtained from ferroelectric hysteresis loops. For PBCTO ceramics, the largest unreleased energy density is 0.72 J/cm3 @ 200 kV/cm; for PBZTO ceramics, the largest unreleased energy density is 0.60 J/cm3 @200 kV/cm. Photocatalytic performance was studied on methylene blue (MB) and methyl orange (MO) dyes under visible irradiation. The degradation percentage of MB dye in the presence of PBCTO and PBZTO was found to be 56% and 98% in 80 min with irradiation. The degradation percentage of MO dye in the presence of PBCTO and PBZTO at their respective wavelength was 48% and 97% in 120 min with irradiation. These bulk ceramics under study have shown interesting multifunctional properties useful for various potential applications.

Synergistic enhancement of plasmon induced photocatalytic and photoelectrochemical performance on ZnWO4/Ag2O@Ag hybrid-heterostructures

A novel hybrid photocatalyst, ZnWO4/Ag2O@Ag heterostructure was synthesized using a simple one-pot microwave treatment with varying concentrations of silver. Physico-chemical characterization was performed to elucidate the synthesized nanohybrids' properties. The photocatalytic activity of both pristine and heterostructure samples was evaluated through the degradation of cationic MB dye. Among the varied Ag concentrations, the 9 % Ag-doped ZnWO4/Ag2O heterostructure exhibited superior degradation performance, with a degradation rate of 93 % achieved within 45 min, surpassing both other Ag concentrations (89 % (90 min) for 1 % Ag, 87 % (80 min) for 3 % Ag, 90 % (80 min) for 5 % Ag and 91 % (45 min) for 7 % Ag) and pristine ZnWO4 (91 % (90 min)) samples. This catalytic enhancement can be attributed to the formation of heterostructures, plasmon-induced absorption enhancement within specific wavelength ranges, and reduced charge recombination rates. UV–visible studies revealed Ag nanoparticles of various sizes in the heterostructures, supported by surface plasmon resonance (SPR) peaks at 480 and 550 nm, respectively. Trapping experiments indicated that •OH and •O2− were the active species in MB reduction for pure and heterostructure samples. Furthermore, the hybrid heterostructure samples exhibited high stability and reusability in photocatalytic degradation. These findings suggest that the ZnWO4/Ag2O heterostructure photocatalysts are promising candidates for environmental remediation applications.

Built-in electric field mediated S-scheme high-quality charge separation in BiVO4/NiAl-LDH heterojunction for highly efficient photocatalytic degradation of antibiotics

As an up and coming technology for antibiotics removal from water, photocatalysis required well-pleasing charge isolation, migration, and utilization efficiency to come true an efficaciously photocatalytic performance, but developing affordable and high-efficiency photocatalyst remains a great challenging. Herein, an emerging S-scheme BiVO4/NiAl-LDH heterojunction was ingeniously fabricated by mulberry-like BiVO4 microrods immobilized onto the surfaces of flower-like NiAl-LDH microspheres. The physicochemical properties of the BiVO4/NiAl-LDH heterojunctions were analyzed by multiple techniques. Expectedly, the manufactured BiVO4/NiAl-LDH heterojunction endowed a significantly strengthened removal rate of tetracycline compared to mono-component BiVO4 and NiAl-LDH under visible light. Specifically, the optimized BVO-NAL-3 manifested the exceptional tetracycline removal efficiency with an apparent rate constant of up to 0.0409 min−1, which was close to 34.1 and 4.4 times more rapid than those of neat NiAl-LDH and BiVO4, severally. This signal enhancement was centrally related to the creation of S-scheme heterojunction, which accelerated high-quality charge separation and strengthened redox capacity under the force of created a built-in electric field, which was corroborated by experiments results together with density functional theory calculations. Besides, the generation of superoxide radicals and photogenerated holes played an imperative role in the tetracycline degradation over BVO-NAL-3. Noteworthily, BVO-NAL-3 expressed the satisfactory stability and exceptional resistance to environmental interferences. More amazingly, other refractory antibiotics including ciprofloxacin, levofloxacin and amoxicillin were also efficaciously eliminated by BVO-NAL-3. Ultimately, the possible degradation mechanism and pathways of tetracycline were logically inferred. This work unveils a valuable afflatus for the reasonable layout and establishment of S-scheme heterojunction with high-quality charge separation for the eradication of antibiotics.

Enhancing photocatalytic hydrogen evolution performance for D-π-A conjugated polymers based on the perylene diimide

Efficient photocatalysts rely on constructing heterostructure with reasonable configuration. In this study, a novel conjugated polymer with a D-π-A structure was fabricated from polycondensation of perylene diimide and dibenzothiophene sulfone through the suzuki coupling reaction, during which the biphenyl was incorporated as a π-bridge. The photocatalytic hydrogen evolution performance of these copolymers were optimized by introducing different mass fractions of π-bridges via adjusting the additions of biphenyls The optimized PyBpDBSO-5 copolymer, with 17 wt.% perylene diimide and 5 wt% biphenyl, obtained photocatalytic hydrogen productivity of 48.54mmol/h g−1 under visible light without adding Pt as cocatalyst, which is 146.1 % improvement compared to the poly(dibenzothiophene-S,S-dioxide) (PDBTSO, 19.72mmol/h g−1). Based on the analysis of physical and chemical properties, electrochemical testing, the significant advantages of D-π-A configuration in promoting light absorption, photogenerated carriers transfer and separation was confirmed, which was further rationalized by the larger co-planarity of the polymer based on DFT calculations. This study provides inspiration about construction of conjugated organic polymer catalyst towards efficient photocatalysts.

N-doping of β-ketoenamine based covalent organic frameworks (COFs) for enhancing photocatalytic oxidation activity

β-ketoenamine-based COFs are widely investigated due to their high stability, good crystallinity and tunable skeleton structures. Nitrogen doping is one of the effective ways to enhance the catalytic activity of COFs. Herein, N-doping of β-ketoenamine-based (0N-TP-COF, 1N-TP-COF, 2N-TP-COF) COFs were successfully constructed by the Schiff base condensation reaction between 1,3,5-tiformylphloroglucinol (TP) and p-phenylenediamine containing different numbers of nitrogen atoms. Studies showed that the as-prepared COFs exhibited more suitable electronic structure and more electron-rich active sites with the increasing of N atoms. Furthermore, the photocatalytic performance of 4-formylphenylboronic acid transformation was 0N-TP-COF (99 %, 48 h) < 1N-TP-COF (99 %, 32 h) < 2N-TP-COF (99 %, 16 h), and the photocatalytic performance of benzylamine coupling was 0N-TP-COF (99 %, 16 h) < 1N-TP-COF (99 %, 3.5 h) <2N-TP-COF (99 %, 1.5 h), respectively. Note that all N-doping COFs have excellent catalytic activity as well as stability, and 2N-TP-COF exhibits the highest catalytic activity. This work demonstrates that doping of nitrogen atoms is an effective way to enhance photocatalytic performance.

ZrO2 nanoparticles for effective dye degradation in wastewater: Synthesis, characterization, and photocatalytic performance under sunlight

The study addresses the critical issue of water contamination, focusing on the photodegradation of methylene blue (MB) dye as industrial waste. A novel method is presented to synthesize zirconium dioxide (ZrO2) nanoparticles (NPs) using zirconium hydrogen phosphate as a precursor. The results proved the formation of spherical nanoparticles with an average particle size of about 23.24 nm, confirmed by scanning electron microscopy (SEM). The structural analysis demonstrated the existence of both tetragonal and monoclinic phases, with the dominance of the tetragonal phase. The photocatalytic evaluation under sunlight irradiation showed an impressive MB degradation efficiency of about 80 % in a relatively short time of 80 min. Thus, the study highlights the potential of ZrO2 NPs sensitized by a novel approach as highly efficient photocatalysis for water treatment.

Boosting hydrogen evolution performance of nanofiber membrane-based composite photocatalysts with multifunctional carbon dots

Recent progress in the co-spinning of nanofibers and semiconductor particles offers a promising strategy for the development of photocatalytic devices, solving aggregation and catalyst recovery challenges. However, composite photocatalysts based on nanofiber membranes often suffer from poor conductivity, low hydrophilicity, and easy recombination of photogenerated electron-hole pairs in the semiconductor components. Here, to tackle the aforementioned issues of ZnIn2S4/polyacrylonitrile (ZIS/PAN) nanofiber-based catalysts, we prepared a composite carbon dots/ZnIn2S4/polyacrylonitrile (CZP) nanofiber membrane by blending carbon dots (CDs) with ZIS/PAN using the electrospinning process. The hydrogen evolution performance of the CZP photocatalyst was significantly improved by CDs, which enhanced the hydrophilicity, increased the light absorption, facilitated the transfer of photogenerated electrons, and reduced the recombination of photogenerated electron-hole pairs. Notably, the optimal CZP photocatalyst achieved a hydrogen evolution rate of 2250 μmol g-1h−1, which is about 23 % higher than that of the nanofiber membrane without CDs and 4.55 times higher than that of ZIS particles. The present work successfully improved the CZP nanofiber membrane of photocatalytic hydrogen evolution performance, and the membrane may benefit further device development by eliminating the need for stirring and simplifying the recovery process.

Improved photocatalytic performance of cobalt doped ZnS decorated with graphene nanostructures under ultraviolet and visible light for efficient hydrogen production

Highly dispersed Cobalt doped ZnS nanostructures were successfully fabricated on the surfaces of graphene sheets via a simple hydrothermal method. X-ray diffraction (XRD), X-ray photocurrent spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were utilized to analyze the structural characteristics of the cobalt doped ZnS decorated with graphene CoxZn1-xS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}{\\rm S}$$\\end{document} rGO nanostructures (NSs). UV-visible optical absorption (UV-vis) studies were conducted to investigate their optical properties. In laboratory studies utilizing water and visible light, the photocatalytic activity of CoxZn1-xS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}S$$\\end{document}rGO NSs at (x = 0, 1, 2, 4 and 6 atm.%) were evaluated. Graphite Oxide (GO) was successfully transformed into sheets of graphene and CoxZn1-xSrGO\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}{\\rm S \\, rGO}$$\\end{document} NSs possessed a crystalline structure according to the findings of XRD, RS and FTIR analysis. SEM investigation showed graphene sheets enhanced with ZnS NSs possessed cuboidal, spheroidal form of structure and displayed a paper like appearance. UV-vis confirmed a noticeable rapid increase in transmittance along the UV wavelength area and confirmed a highly transparent NSs in the wavelength range of (180-800 nm). Calculations using density functional theory (DFT) revealed that the Co NSs have more negative conduction bands than ZnS, allowing for effective electron transfer from cobalt to ZnS and exhibiting a band gap decrease as Co content increased. The Co0.04Zn0.96S\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_{0.04}{\\rm Zn}_{0.96}S$$\\end{document} rGO NSs sample had the highest photocatalytic activity, measured at 7648.9μmolh-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$7648.9 \\, \\upmu {\\rm mol} \\, {\\rm h}^{-1}$$\\end{document}. A combination of improved dispersion properties, greater surface area, increased absorption and enhanced transfer of photogenerated electrons, CoxZn1-xS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rm Co}_x{\\rm Zn}_{1-x}S$$\\end{document} rGO NSs increased the photocatalytic hydrogen generation activity.

Boosting photocatalytic efficiency and nonlinear optical response of graphitic carbon nitride by infusing carbon nanotubes

Nanostructured materials are widely studied for their light-driven physical and chemical processes, which are key to their potential in photophysical applications. We introduce a one-pot solid-state pyrolysis technique for the synthesis of graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) composites. The formation of the composite was characterized through X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. Notably, UV-vis diffuse reflectance spectroscopy indicated a reduction in the bandgap of pure g-C3N4 from 2.6 eV to 2.35 eV with the incorporation of 0.5 wt% CNT. The nonlinear optical transmission of the samples was analyzed at 532 nm using the open-aperture Z-scan technique employing 5 ns laser pulses, revealing a twelve-fold increase in the two-photon absorption coefficient (b) for g-C3N4/CNT0.5 compared to pristine g-C3N4. Remarkably, g-C3N4/CNT0.5 showed enhanced photocatalytic efficiency in degrading bisphenol A (BPA), with the kinetic constant (k) being ten times higher than that of pure g-C3N4. The improved photocatalytic performance of g-C3N4/CNT0.5 is attributed to the presence of CNTs, which act as effective electron acceptors and transfer channels, significantly enhancing the separation of photogenerated charge carriers in g-C3N4, as evidenced by the decreased intensity in the photoluminescence spectrum.

Size-modulated Pt nanoparticles for low-temperature plasmon-enhanced hydrogen production from aqueous phase reforming of methanol

Al2O3 supported Pt nanoparticles photocatalyst enables efficient hydrogen production (115.2 μmol min−1 gcat−1) through aqueous phase reforming of methanol (APRM) reaction under light irradiation at low temperatures of 150 °C, which is 6 times higher than that of APRM reaction conducted in the dark. We demonstrate that the particle size of Pt nanoparticles greatly affected the light absorption ability, which is of great importance for light utilization of the photocatalyst. The medium particle size of Pt nanoparticles enables the lower electron density states, which is benefit for the dehydrogenation of methanol and the sequential water–gas shift (WGS) reaction and eventually promoted the photocatalytic performance for hydrogen production.

​The structural regulation of photosensitive unit and conjugation in COFs for efficient photocatalytic H2 evolution.

The photosensitive unit and conjugation play a significant role in photocatalytic performance of covalent organic frameworks (COFs). In this work, a series of COFs that introduced the phenyl phenanthridine as photosensitive unit with different planarity of linkages were synthesized and the common regulation between them for photocatalysis hydrogen evolution reaction (HER) was also studied. The results indicate that DHTB-PPD, with 2/3 planarity linkages (β-ketoenamine/imine is 2/3) and the phenyl phenanthridine as building blocks, shows the narrowest bandgap and the strongest charge separation efficiency. Therefore, it shows the highest H2 production rate of 12.13 mmol g-1 h-1. The optimal photocatalytic efficiency of DTHB-PPD can be attributed to the combined effect of the photosensitive unit and the long-range ordering of the COF skeleton. According to The Density Functional Theory (DFT), the O site on β-ketoamine is the most possible H2 generation site, but the photocatalytic efficiency of TP-PPD, with the highest skeletal conjugation and the highest proportion of β-ketoamine is not the most efficient photocatalyst, indicating that the long-range ordering of COFs is important on photocatalytic performance. Thus, these findings provide valuable guidance for the structural design of COFs photocatalysts.

Peptide-Guided Metal-Organic Frameworks Spatial Assembly Sustain Long-Lived Charge-Separated State to Improve Photocatalytic Performance.

The controlled fabrication of spatial architectures using metal-organic framework (MOF)-based particles offers opportunities for enhancing photocatalytic performances. The understanding of the contribution of assembly to a precise photocatalytic mechanism, particularly from the perspective of charge separation and extraction dynamics, still poses challenges. The present report presents a facile approach for the spatial assembly of zinc imidazolate MOF (ZIF-8), guided by β-turn peptides (SAZH). We investigated the dynamics of photoinduced carriers using transient absorption spectroscopy. The presence of a long-lived internal charge-separated state in SAZH confirms its role as an intersystem crossing state. The formation of an assembly interface facilitates efficient electron transfer from SAZH to O2, resulting in approximately 2.6 and 2 times higher concentrations of superoxide (·O2-) and hydrogen peroxide (H2O2), respectively, compared to those achieved with ZIF-8. The medical dressing fabricated from SAZH demonstrated exceptional biocompatibility and exhibited an outstanding performance in promoting wound restoration. It rapidly achieved hemostasis during the bleeding phase, followed by a nearly 100% photocatalytic killing efficiency against the infected site during the subsequent inflammatory phase. Our findings reveal a pivotal dynamic mechanism underlying the photocatalytic activity of control-assembled ZIF-8, providing valuable guidelines for the design of highly efficient MOF photocatalysts.

Constructing type II heterojunction of 2D/1D Pg-C3N4/Ag3VO4 nanocomposite with high interfacial charge separation for boosting photocatalytic CO2 reduction under solar energy

The well-designed, template-free synthesis of 2D protonated g-C3N4 nanosheets (Pg-C3N4) coupled with novel 1D Ag3VO4 nanorods has been investigated to construct 2D/1D interface heterostructures with strong electrostatic interactions between the positively charged 2D Pg-C3N4 nanosheets and the negatively charged 1D Ag3VO4 nanorods. The coupling of Pg-C3N4 and Ag3VO4 with desirable characteristics resulted in a 2D/1D interface heterojunction with a type II charge carrier transfer mechanism, effectively maintaining and utilizing charge carriers. The 2D/1D Pg-C3N4/Ag3VO4 exhibited remarkable photocatalytic performance for CO2 conversion with H2O, resulting in maximum CH4 and dimethyl ether (DME) production of 352.3 and 130.9 µmol/g-cat, respectively. A quantum yield of 0.23 % for CH4 generation was achieved over the 2D/1D Pg-C3N4/Ag3VO4, which was 2.9 and 1.4 times higher than that of the Pg-C3N4 and Ag3VO4 samples, respectively. The improvement in photocatalytic performance primarily stems from the effective interaction between Pg-C3N4 and ternary Ag3VO4, leading to enhanced transfer and separation of photoinduced charge carriers through the creation of a type II heterojunction. The findings of this study are useful in designing template-free heterojunctions for photocatalytic CO2 conversion and other solar energy applications.

Assessment of photocatalytic activities of layered double hydroxide@petrochemical sludge biochar for sulfamethoxazole degradation

Layered double hydroxides (LDHs) as one of the popular photocatalysts have the drawbacks of compact structural arrangement and pronounced nano-particle clustering, which affect their photocatalytic performance for the degradation of organic pollutants from water or wastewater. Using biochar as a substrate matrix to support LDHs may be a good way to improve the photocatalytic performance of LDHs by avoiding agglomeration effect, promoting the separation of photogenerated electrons from holes for organics degradation. In this study, the composite of CoFe-LDH and petrochemical sludge biochar (CoFe-LDH@PBC) was fabricated and applied for the first time as photocatalyst for catalytic degradation of sulfamethoxazole (SMX). Results showed CoFe-LDH@PBC800/UV system exhibited excellent photocatalytic activity on SMX degradation than single CoFe-LDH/UV, PBC800/UV, or PBC105/UV system under various reaction conditions (photocatalyst dosage, pH, system speed, and SMX concentration). 100 % of SMX degradation efficiency and 88.98 % mineralization efficiency could be achieved in CoFe-LDH@PBC800/UV system within 100 min. The corresponded pseudo-first-order kinetic rate constant (kobs) of SMX degradation in CoFe-LDH@PBC800/UV system was 0.032 min−1, which was 3.20, 8.00, and 2.46 times higher than that of CoFe-LDH/UV, PBC800/UV, and PBC105/UV, respectively. In photocatalytic process, OH, O2−, and h+ participated in SMX degradation, among which h+ or OH played a major role. The good photocatalytic performance of CoFe-LDH@PBC800 composite was related to its excellent physiochemical properties, such as lower band gap (2.39 eV), high graphitization degree, and high conductivity, enabling efficient e−/h+ separation of photocatalyst for SMX degradation. Four distinct pathways of SMX degradation were proposed based on DFT theoretical calculations and byproducts of SMX degradation identified by LC-MS. Additionally, results from recycling tests suggested CoFe-LDH@PBC800 composite possessed a favorable reusability and could be applied for photocatalytic degradation of SMX at least 3 times. Over all, CoFe-LDH@PBC800 composite was proved to be an efficient photocatalyst for antibiotic degradation in water or wastewater and the reuse of petrochemical wastewater sludge was expected to realize the concept of resourceful and high-value utilization of waste biomass.

In-situ construction of Bi-MOF-derived S-scheme BiOBr/CdIn2S4 heterojunction with rich oxygen vacancy for selective photocatalytic CO2 reduction using water

In this study, a highly selective MOF-BiOBr/CdIn2S4 (MOF-BiOBr/CIS) heterostructure with CdIn2S4 nanosheets grown in situ on the tubular structure derived from Bi-MOF-based BiOBr was successfully constructed using a hydrothermal method. Under simulated solar light without sacrificial or photosensitizing agents, the 20-MOF-BiOBr/CIS composite exhibited excellent photocatalytic CO2 performance, achieving production rates of 30.18 μmol‧g−1‧h−1 for CO and 1.50 μmol‧g−1‧h−1 for CH4. Compared to pure MOF-BiOBr and CdIn2S4, the CO production rates were increased by approximately 9 and 116 times, respectively. It was revealed that the 20-MOF-BiOBr/CIS composite with rich oxygen vacancy exhibited close interfacial contact and efficient charge transfer. The formation of MOF-BiOBr/CdIn2S4 heterojunction thereby provided efficient CO2 photocatalytic reduction. The CO selectivity of 20-MOF-BiOBr/CIS reached 83.4 %, and the MOF-BiOBr/CIS heterojunction exhibited good stability over multiple cycles. Furthermore, a mechanism for enhanced photocatalytic CO2 reduction by the MOF-BiOBr/CIS heterojunction was also proposed.

The role of spectral matching in enhancing photocatalytic performance with TiO2-rGO catalysts for metronidazole wastewater elimination

The role of spectral matching in enhancing the photocatalytic degradation of metronidazole using TiO2-reduced graphene oxide (TiO2-rGO) systems is investigated in this study. A rapid, one-step microwave synthesis method was utilized to produce TiO2-rGO composites with varying proportions of graphene oxide. Characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), were employed to elucidate the morphological and structural attributes of the photocatalysts, thereby facilitating their application in photocatalysis. Spectral matching between the photocatalytic material and the irradiation source was identified as critical to the methodology. Experiments conducted under LED light tailored to the absorption spectra of the catalysts demonstrated that the TiO2-rGO system with a 2 % GO composition achieved the highest metronidazole degradation efficiency, reaching 95 % degradation after 120 min of irradiation. Furthermore, the catalyst maintained high reusability, with only a 5 % decrease in efficiency after five cycles of reuse. The Electrical Energy per Order (EEO) was determined to be 3.51 kWh/m3, indicating the system’s high energy efficiency. The study emphasizes the real-world applicability of TiO2-rGO composites for wastewater treatment, particularly in terms of environmental sustainability and operational cost-effectiveness.