Photocatalytic Ability Research Articles

Combining rhombohedral dodecahedral ZnO with g-C3N4 nanosheets for enhanced photocatalytic activity

Photocatalysis technology is an effective method to remove pollutants in aquatic environment assisted by solar energy. Herein, the rhombohedral dodecahedral ZnO was dispersed on the g-C3N4 nanosheets for the construction of ZnO/g-C3N4 heterojunction via the combination of solvothermal method and calcination. The obtained ZnO/g-C3N4 heterojunction manifests excellent photocatalytic ability for methyl orange (MO). Especially, the optimal ZnO/g-C3N4 composite with the ZnO content of 10 wt% (ZC-3) exhibits the degradation efficiency of MO as high as 98.0% under visible-light of 60 min. A series of factors were all-around investigated, such as initial pH, photocatalyst dosage, initial MO concentration, organic anions, humic acid and other dyes. The photocatalytic degradation behavior of MO complies with the first-order reaction kinetics, and the apparent rate constant (kapp) of ZC-3 is 2.3 and 13.4 times than that of pure g-C3N4 and pure ZnO. Meanwhile, the ZnO/g-C3N4 heterojunction exhibits satisfactory cyclic stability and its photocatalytic mechanism is postulated. Therefore, the ZnO/g-C3N4 heterojunction possesses great economic utilization value and is expected to be widely used for wastewater remediation.

A p-n heterojunction PdO/CeO2 photocatalysts with enhanced photocatalytic ability for reduction of Hg(II) ions from aqueous solution

Heterostructured photocatalysts represent an essential role in the catalytic redox reactions in wastewater during illumination. In this contribution, p-n heterojunction PdO/CeO2 photocatalysts were constructed with enhanced photocatalytic ability for the reduction of Hg(II) utilizing HCOOH as hole scavengers under visible light. PdO NPs were uniformly spread on the mesoporous CeO2 surface, to act as potential separation centers of electrons and holes. The synthesized PdO/CeO2 nanocomposites exhibited an excellent photocatalytic ability, contrasted to the bare CeO2 NPs. The photocatalytic ability of PdO/CeO2 nanocomposites for reduction of Hg(II) has existed in the trends of 2%PdO ≥1.5%PdO >1%PdO >0.5 % PdO/CeO2 nanocomposites > bare CeO2 NPs. A photocatalytic ability of 100 % for Hg(II) reduction was achieved within 40 min utilizing 1.5 % PdO/CeO2 nanocomposites, which was 2.2 folds greater than that of bare CeO2 NPs. The rate constant of 1.5 % PdO/CeO2 nanocomposite (0.106 min−1) is more 9.9 times than that CeO2 NPs (0.0107 min−1). The enhancement photocatalytic ability of PdO/CeO2 can be interpreted to the wide surface area, narrow bandgap, numerous active sites, fast mobility, efficient diffusion of Hg(II), and the high separation rate of photocarriers. Considering the promotion photocatalytic ability of heterojunction PdO/CeO2 nanocomposites, the heterostructure photocatalyst is of magnificent importance to the photocatalytic redox reactions and exhibits a significant effect on our human health and ecological environment.

Designing Polychromatic Er3+/Yb3+-Codoped Bi2WO6 Upconverting Nanoparticles with Enhanced Visible-Light-Triggered Photocatalytic Properties toward Tetracycline Degradation.

To address the unsatisfactory photodegradation capacities of photocatalysts, Er3+/Yb3+-codoped Bi2WO6 (Bi2WO6:Er3+/xYb3+) nanoparticles (NPs) with polychromatic upconversion (UC) emission and boosted visible-light-triggered photocatalytic abilities were designed. First-principles density functional theory was employed to study the impact of Er3+ and Yb3+ codoping on the electronic structure of Bi2WO6. Upon 980 nm excitation, the resultant NPs emitted polychromatic UC emissions caused by energy back transfer from Er3+ to Yb3+. Moreover, the involved UC emission mechanism was clarified through examining the pump power related to UC emission spectra. By investigating the visible-light-induced tetracycline (TC) decomposition, the photocatalytic activities of developed NPs were explored, where Bi2WO6:Er3+/0.07Yb3+ NP can degrade 81.76% of TC within 30 min, with a k value of 0.0552 min-1. Both the theoretical calculation and trapping results reveal that the •O2-, h+, and •OH were formed during the pollutant removal process. Additionally, the toxic TC can be photodegraded to nontoxic products via the synthesized photocatalysts, leading to wastewater purification. These achievements manifest that Bi2WO6:Er3+/xYb3+ NPs are promising visible-light-triggered photocatalysts to degrade pollutants, and our findings also propose a facile approach to regulate the photocatalytic activities of photocatalysts via utilizing doping and UC emission strategies.

Synthesis, structural analysis and photocatalytic ability of novel Mg-Al-Ag and Mg-Al-Ag-Zn hydrotalcite-like compounds

To date, various hydrotalcite HT (Mg-Al) compounds are investigated to expand hydrotalcite-like material’s applications, especially for dye treatment purposes. From the characteristics of silver together with zinc oxide (ZnO) such as antibacterial along with photocatalytic behaviors, the combination of Ag-ZnO with hydrotalcite Mg-Al is necessitous. Consequently, this work aimed to synthesize and characterize hydrotalcite Mg-Al doped with Ag(I) (HT-Ag) as well as doped with Ag(I) and Zn (II) (HT-Ag-Zn) by the co-precipitation method. Both Ag(I) and Zn(II) were doped simultaneously on hydrotalcite Mg-Al for the first time. The characteristics of synthesized HT-Ag and HT-Ag-Zn were identified using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Vis diffuse reflectance spectroscopy (UV-Vis DRS) methods. The total surface area and pore size of the samples were evaluated due to BET surface area measurement. The obtained results indicated that regular Mg-Al-Ag and Mg-Al-Ag-Zn hydrotalcite-like compounds were synthesized successfully. Furthermore, the HT-doped materials implied the capacity to inhibit the growth of gram-negative bacteria such as E. coli, and gram-positive bacteria such as S. aureus. Besides, these doped materials were applied to the photocatalysis of Remazol Midnight Black (RMB) dyes. The HT-Ag exhibited higher photocatalytic capacity than the HT-Ag-Zn. The optimization process for degrading RMB dye molecules was carried out using response surface methodology combined with a Box-Behnken design and a quadratic model. In addition, the catalytic repeatability of the HT-doped material was determined to give suggestions for the potential application of HT-Ag as a photocatalyst.

Designing Bi2O3-Sn3O4 Z-scheme heterojunction on TiO2 NTs for improving photocatalytic performance

The design of semiconductor heterostructures as the effective strategy are recognized to enhance the photocatalytic capacity of photocatalysts for the settlement of energy shortage and pollutant treatment. To efficiently utilize solar energy, the Bi2O3-Sn3O4 nanoparticles with the Z-scheme energy band structure were synthesized on TiO2 nanotube arrays (TiO2 NTs) by the solvothermal deposition method. The TiO2 NTs/Bi2O3-Sn3O4 exhibited the outstanding photocatalytic dye degradation and Cr(VI) removal, which was much higher than those of single Bi2O3 or Sn3O4 sensitized samples. The H2 evolution test indicated that the Bi2O3-Sn3O4 cosensitization dramatically enhanced the photocatalytic H2 generation ability of TiO2 NTs with the rate of 58.75 μmol·h−1·cm−2. The high photoelectric conversion was also confirmed, and the outstanding photocatalytic performance was further revealed by the contrast experiment. The plausible photocatalytic mechanism based on the ESR and capturing experiments indicated that the Z-scheme energy band structure induced the photoelectron separation and the generation of O2 and OH radicals, which was the decisive role for the improved photocatalytic performance.

Polyphenol assisted assembly of prussian blue analogs nanocrystals decorated 3D GO functional microspheres for polymer fiber bifunctional membrane with high oil-water emulsion permeability and powerful photocatalytic self-cleaning ability

Due to the intricate components of wastewater and physical stacking of graphene oxide (GO), the current GO membranes exhibit the fatal defects of low porosity and poor anti-fouling ability. Herein, a three dimensional (3D) FeCo-PBA@GO functional microsphere was constructed via anchoring GO nanosheets onto hard template of 3D polymethyl methacrylate (PMMA) microsphere driven by hydrogen bond and van der Waals force. On this basis, the Prussian blue analogs nanocrystals (FeCo-PBA) grew in situ on such functional microsphere and further assembled onto porous polyacrylonitrile (PAN) fiber mat through the tannic acid assisted spraying technique, resulting in highly permeable and photocatalytic self-cleaning FeCo-PBA@GO/PAN fibrous composite membrane. Interestingly, the unique 3D nanostructure of FeCo-PBA@GO microsphere arranging on membrane surface effectively prevented the dense physical stacking of GO nanosheets and increased the oil repellence property, thereby regulating the water channel and breaking through permeability limitation of membrane. As a result, the composite membrane exhibited superior separation fluxes (˃3029 L m−2 h−1) for different oil/water (O/W) emulsions, with rejection rate above 99.0 %. Owing to rich active sites and enhanced electron/mass transport property of FeCo-PBA functional layer, the composite membrane could effectively degrade various dyes by peroxymonosulfate (PMS) activation, with the degradation efficiency of 93.1–96.9 % within 40 min and demonstrated favorable antifouling and photocatalytic self-cleaning ability after cycling separation of O/W emulsion. In addition, the generated multiple reactive oxygen species and photocatalytic mechanism were proposed. This work provides a versatile pathway to prepare multifunctional GO advanced membranes for large-scale treatment of complex emulsified oily wastewater.

Copper decorated cuprous oxide–carbon nitride plasmonic p-n heterojunction with high-efficiently charge transfer for photodegradation of tetracycline

In this work, a novel copper decorated cuprous oxide–carbon nitride (Cu@Cu2O-g-C3N4) plasmonic p-n heterojunction was prepared by solvothermal method using pre-synthesized carbon nitride and Cu@Cu2O precursors as raw materials. The morphology observation for the sample exhibits that Cu2O precursor is dispersed from micrometer octahedrons to the particles with the sizes of 20 ∼ 200 nm under action of dimethylformamide, forming a close contact between Cu nanoparticles, Cu2O particles and g-C3N4 stacking flakes. The results of photodegradation shown that 96.4 % of 10 mg·L−1 tetracycline (TC) solution was decomposed within 60 min and degradation rate decreased by 9.2 % after five cycles. Photoelectrochemical characterizations indicated that photocatalytic performance of Cu@Cu2O-g-C3N4 was attributed to high-efficiently charge transfer base on the synergistic effect of heterojunction and plasmon resonance. The formation of p-n type built-in electric field between Cu@Cu2O and g-C3N4 enhances photocatalytic oxidative and reductive ability of the catalyst, and dual coupling effects induced by the localized surface plasmon resonance of Cu nanoparticles promote the amount of photogenerated electrons. This work provides a strategy for preparing efficient p-n heterojunction photocatalysts with plasma coupling effects by reconstructing the junction interface using facile solvothermal method.

Variable valence I3−/I− ionic bridge assisting CuI nanoparticle/BiOI nanosheet S-scheme photocatalyst with hydrophobic surface for boosting CO2 conversion with 100 % CO selectivity

The photocatalyst film, composed of tetragonal BiOI nanosheets and cubic phase CuI nanoparticles, was synthesized on the FTO substrate by a simple electro-deposition method. The orderly crisscrossed nanosheet structure caused exterior hydrophobic property, resisting the excess H2O molecules and further inhibiting the competitive H2O reduction process. The novel BiOI/CuI catalyst exhibited excellent photocatalytic ability of CO2 reduction into CO with 100 % selectivity in H2O vapor. Typically, the optimal 150BiOI/CuI photocatalyst exhibited CO yield of 7237.65 μmol/cm2 after 11 h of simulated sunlight illumination, achieving quantum efficiency of 2.5 % at 380 nm. The excellent performance of the BiOI/CuI composite film in photocatalytic CO2 reduction can be attributed to the construction of hydrophobic surface and S-scheme heterojunction with I3−/I− redox mediator, as confirmed by the in-situ XPS, hole injection test and cyclic voltammetry results. This study lays the groundwork for employing highly efficient iodide-based photocatalysts in gas-liquid-solid triphase catalytic systems.

CdS quantum dots modified two-dimensional MXene photocatalytic membrane for efficient removal of organic dyes from aquatic systems

MXene, a novel two-dimensional (2D) material, has been applied for the removal of dye molecules from wastewater; owing to its ability to stack into unique interlayer permeation channels. However, the narrow interlayer permeation channels of MXene limit its high permeability, and the dye contaminants tend to block the channels on the membrane surface as well as between the laminae. In view of this, CdS quantum dots (QDs) were incorporated with photocatalytic ability into the MXene channels, and the fabricated CdS QDs@MXene/PVDF photocatalytic composite membrane had high separation efficiency by using PVDF polymer as the support layer. The results manifested that; the CdS QDs were homogeneously dispersed in the MXene separation layer, and the introduction of CdS QDs optimized the interlayer permeation channels of MXene, with permeate flux of 502.6 L·m−2·h−1. The composite membrane exhibited an excellent removal of Congo red and Rhodamine B (CR and Rh B) dyes under the coupling of membrane separation and photocatalytic process, with the optimal removal ratio of 97.3 % for CR and 98.5 % for Rh B, respectively. Moreover, the CdS QDs endowed the membrane with self-cleaning ability, superior permeability and selectivity under five consecutive photocatalytic cycles, demonstrating the great in-situ resistance to contamination. After five intermittent cycles, the dye retention rate still exceeded 90 % and the permeate flux reached 388.0 L·m−2·h−1. This study provides an exceptional reference for quantum dots modified two-dimensional MXene membranes.

Synthesis, structure, theoretical calculation and photocatalytic property of a novel Mn(II) supra-molecular compound containing SCN- and 2,2′-bipyridine ligands

A novel supra-molecular compound [Mn(SCN)2(byp)2] 1 (byp = 2,2′-bipyridine) was synthesized under hydrothermal conditions. Noteworthily, the SCN- in the title compound is derived from the in situ reaction of salicylaldehyde thiosemicarbazone. X-ray single-crystal diffraction analysis shows compound 1 is only a mononuclear structure, but it is expanded into a 3D supramolecular structure via H-bonds and π···π stacking. Hirshfeld Surface analysis shows C⋯H, H⋯H and S⋯H interaction are the main contribution of intermolecular interactions in the formation of compound 1. All of title compounds were characterized by IR spectroscopy, elemental analysis, XRD, XPS and TG analysis. The energy framework of compound 1 is dominated by dispersion interaction. The photocatalytic degradation ability of compound 1 for methylene blue is verified by photocatalytic degradation experiments (pH = 4: 44.6 %; pH = 7: 76.2 %; pH = 10: 78.8 %). Furthermore, the potential photocatalytic mechanism of compound 1 is inferred by UV–vis absorption spectra and Mott–Schottky curve.

Facile fabrication of heavily N-doped Zn0.67Cd0.33S nanocatalyst with congenital sulfur vacancies for efficient photocatalytic reduction of water and hexavalent chromium

Twinned zinc cadmium sulfide (ZnxCd1-xS) has been widely investigated for efficient Cr(VI) reduction and H2 production under light irradiation due to its inherent homojunctions. However, long-distance migration of charge carriers and relatively low conduction band level inevitably cause low photocatalytic reduction ability. Herein, we developed a DMF-involved one-step solvothermal strategy to introduce N heteroatoms into Zn0.67Cd0.33S crystals incorporated with dopant-induced S vacancies. The synergetic promotion of the elevated conduction band, coupled with the robust aggregation of interactants, effectively impeded the recombination behavior of charge carriers, leading to a notable increase in photocurrent density (∼2.4 times), electron density (∼2.8 times), and a higher photo-reducing potential. The optimal NZCS-10 demonstrated a superior photocatalytic Cr(VI) reduction efficiency of 99.32 % within 30 min, and rendered ca. 5.8- and 7.6-fold enhancement for H2 evolution rate under alkaline and acidic conditions, respectively. This study provided a universal strategy for gaining highly reductive transition metal sulfides with more active sites.

Magnetically-manipulatable and self-cleaning lab-on-a-bubble Ag@TiO2@Fe3O4 hollow spheres and their application in SERS detection and photocatalytic degradation

In this study, an innovative highly sensitive self-cleaning Lab-on-a-bubble SERS substrate: Ag NPs@TiO2@Fe3O4 hollow spheres, was developed using spray pyrolysis and following depositions. The reusable and magnetically controllable substrate consists of iron oxide hollow spheres (Fe3O4) covered by a TiO2 shell and silver nanoparticles (Ag NPs) deposited on the outer surface. Experimental results show that this new composite SERS substrate exhibited a low limit of detection (LOD) down to 10-10M, and the enhancement factor (EF) reached 1.01 X107. It suffered only 3 % loss after 10 repeatable recycle tests if the self-cleaning under UV was performed after each test. This novel substrate possessed good photocatalytic degradation ability for methylene blue (MB) dyes even under visible light. In that case, MB can be dissociated up to 99.8 % and the reaction rate constant (K) reached 0.0271/min. Taking advantage of this, the feasibility of reusable SERS detection through self-cleaning under visible light was also demonstrated.

Eco-friendly and sustainable synthesis of carbon quantum dots from waste sulfuric acid of alkylation

Waste sulfuric acid of alkylation (WSAA) poses a challenge in industrial alkylation oil production due to its substantial yield and high treatment costs. This study introduces a novel hydrothermal method that ingeniously couples the treatment of WSAA with the synthesis of high-quality carbon quantum dots (CQDs), offering a cost-effective and controllable approach. Through this method, the particle size and surface functional groups of the resulting CQDs can be precisely regulated. The average particle size tunes from 17.97 nm to 2.42 nm via increasing the hydrothermal temperature, and nitrogen-containing groups can be introduced through adding nitrogen sources during hydrothermal process. The prepared CQDs exhibit notable performance in photocatalysis and heavy metal detection, such as CQDs modified graphite carbon nitride has improved photocatalytic degradation ability and Hg (II) detection ability. Additionally, the environmental impact of the proposed method is substantially minimized, demonstrating a smaller footprint on ecosystems compared to conventional industrial disposal processes. Moreover, the economic cost associated with the method is significantly reduced by approximately 48.4 %, further highlighting its efficiency. Utilizing WSAA as a raw material for CQDs not only facilitates the recycling and sustainable utilization of waste but also enables low-cost production of high-performance carbon materials, presenting a mutually beneficial approach.

Electrochemical remediation of methyl orange over reusable biochar ferrite coated photocatalytic plates

Biochar (BC) obtained from biomass pyrolysis holds immense potential for environmental remediation. The efficiency of BC can further be enhanced by incorporating metal nanoparticles (NPs) in the porous carbon matrix. In the present work nanocomposites (NCs) were prepared by the addition of ferrite nanoparticles (FNPs) into an oxidized BC matrix to create BC /Fe3O4 (BCF). This process improves BC stability, electron transfer, conductivity, and photocatalytic ability for dye degradation. Microstructure and functional group analysis of BCF was performed by SEM, XRD, and FTIR showing intercalation of FNPs with surface functionalities of oxidized BC matrix. The B-H curve of FNPs and BCF reveals super paramagnetic behavior with saturation magnetization (Ms, emu/g) of 67.36 and 20.01 respectively. BET surface area analysis shows surface area (m2/gm) 45.81 and 44.19 for oxidized BC and BCF respectively, that attributed to partial blocking of porous carbon matrix by FNPs. UV-DRS supports the semiconducting behavior of BCF with a significantly reduced band gap (eV) of 2.95 over pristine BC (4.76). BCF-coated photocatalytic plates (PCPs) were developed and utilized for the remediation of methyl orange (MeO) in water samples. Degradation of MeO was investigated over time by electrochemical methods. The square wave voltammetric method showed the limit of detection and quantification of 0.09 ppm and 0.28 ppm respectively for MeO over a glassy carbon electrode in 0.1 M acetate buffer. BCF-derived PCPs rendered ∼99 % degradation efficiency against MeO (50 mgL−1) under UV radiation over 240 min. Developed PCPs demonstrate reusability up to 5 cycles without any further purification step and offer efficient degradation of MeO making them suitable for the treatment of water polluted with dyes.

Emerging Roles of Graphitic Carbon Nitride-based Materials in Biomedical Applications.

Graphite carbon nitride (g-C3N4) is a two-dimensional conjugated polymer with a unique energy band structure similar to graphene. Due to its outstanding analytical advantages, such as relatively small band gap (2.7 eV), low-cost synthesis, high thermal stability, excellent photocatalytic ability, and good biocompatibility, g-C3N4 has attracted the interest of researchers and industry, especially in the medical field. This paper summarizes the latest research on g-C3N4-based composites in various biomedical applications, including therapy, diagnostic imaging, biosensors, antibacterial, and wearable devices. In addition, the application prospects and possible challenges of g-C3N4 in nanomedicine are also discussed in detail. This review is expected to inspire emerging biomedical applications based on g-C3N4.

Activation of peroxymonosulfate under visible-light illumination for enhanced degradation of acetaminophen by self-assembly iron phosphorus/hexagonal tubular graphite carbon nitride

Improving the visible light response by sulfate-based advanced oxidation processes (S-AOPs) is a promising method for the efficient degradation of organic matter in water. Herein, we facilely fabricated the iron phosphorus/hexagonal tubular graphite carbon nitride (FeP/HTCN) composites via two-phase hydrothermal supramolecular self-assembly and thermal-condensation method. FeP/HTCN with the shape of hollow hexagonal tubular loaded iron phosphorus particles was first synthesized. The results suggested that the loading of iron phosphate greatly enhanced its ability to activate peroxymonosulfate (PMS) while also improving the photocatalytic ability of the catalyst due to its smaller bandgap. The combined effect of iron phosphate, HTCN, and visible light (wavelength ≥ 420 nm) assistance facilitated the enhancement of the reaction activity. Electron paramagnetic resonance techniques (EPR) and radial quenching experiments validated that singlet oxygen (1O2) derived from superoxide was the main active species. The degradation pathways of acetaminophen (APAP) were determined and the mechanism of mineralization and decomposition was demonstrated. This work provided a proposal for the application of iron salts represented by iron phosphate in S-AOPs.

Facile construction of a bifunctional Eu-MOF for selective fluorescence sensing and visible light photocatalysis of tetracycline

Contamination detection and removal are important steps in environmental monitoring and cleanup. In this study, europium metal-organic framework structures (Eu-MOF) were designed and prepared that can act as fluorescent probes and photocatalysts for the detection and removal of tetracycline (TC) antibiotics. Eu-MOF was generated by a one-step solvothermal method using europium ion as the metal ion and terephthalic acid as the organic ligand source. The red fluorescence of Eu-MOF is selectively enhanced by TC due to the antenna effect. Eu-MOF, which has a linear range of 0.5–60 μM, can be utilized as a fluorescent probe for tetracycline detection based on this phenomena. In particular, Eu-MOF was found to be able to effectively photocatalyze the degradation of TC, with tetracycline removal rates of about 70 % and 55 % after 180 min of irradiation under ultraviolet light (UV) light and simulated visible light, respectively. The photocatalytic ability of Eu-MOF originated from the generation of hydroxyl radicals (•OH), superoxide radicals (•O2−) and electron holes (h+) under light irradiation. This study innovatively proposed a bifunctional Eu-MOF for TC fluorescence detection and photocatalytic degradation, which provides a novel method for the quick and easy identification and elimination of pharmaceutical contaminants. It can also provide some reference value for the construction of ratiometric fluorescent probes and heterojunction photocatalysts and their application in the treatment of water pollution.

Leaf Mediated <i>Curcuma sp.</i> Silver Nanoparticles as Catalyst - Evaluating Their Antioxidant, Cytotoxicity, Para-Nitrophenol Catalytic and Photocatalytic Activity

Nanotechnology is a fast-rising market in catalytic research; however, the production of eco-friendly nanoparticles remains a significant challenge. In this study, silver nanoparticles (AgNPs) were synthesized from the agro-industrial waste of leaves of <em>C. longa, C. aromatica, C. caesia, C. zedoaria, </em>and <em>C. amada </em>at RT after 24 h, which was confirmed with UV-spectrophotometric evaluation between 320-520 nm. SEM revealed cubic and 30-50 nm AgNPs, while band-gap energy was presented as semi-conductors. Synthesized AgNPs were experimented for their antioxidant, cytotoxic, PNP-catalytic, and photocatalytic activity. The antioxidant assays were determined for WEs and AgNPs. The AgNPs revealed higher TFC, TPC, and TAC than WEs. Cytotoxicity of AgNPs was assessed with the viability of <em>Artemia salina </em>and approved to be non-toxic<em>. </em>PNP catalysis was executed with 4000 ppm AgNPs, and remarkable PNP degradation was obtained within 30 minutes. Photocatalytic ability of 4000 ppm and 266.67 ppm AgNPs were tested to degrade methyl-orange, and a rapid degradation was observed with NaBH<sub>4</sub>. Results of these assays reveal that synthesized AgNPs are potential candidates for integration into the manufacturing of catalytic and photocatalytic agents; thereby, these AgNPs can improve the quality of life by providing cleaner environments for organisms.

Efficient removal of Cr (VI) by Bifunction zinc porphyrin COF: Coupling adsorption with Photocatalysis, performance Evaluation, and mechanism analysis

HypothesisHexavalent chromium, recognized as one of the most toxic heavy metals, demands the development of advanced materials capable of both adsorption and photocatalysis for effective Cr (VI) removal. ExperimentsThis study successfully synthesized a two-dimensional zinc porphyrin covalent organic framework (ZnPor-COF) via a solvent-based method. Performance evaluations have demonstrated that the ZnPor-COF possesses outstanding capabilities for the adsorptive and/or photocatalytic elimination of Cr (VI). Particularly noteworthy is the observation that when adsorption and photocatalysis are coupled, the ZnPor-COF attains an exceptional 99.7 % removal rate for a Cr (VI) concentration of 30 mg/L within just 60 min, with minimal susceptibility to coexisting ions. After five consecutive cycles, the material sustains a removal efficiency of 90 %, indicative of its robust cyclability. FindingsTheoretical calculations, as well as experimental validations, have indicated that the integration of Zn ions into the porphyrin COF not only results in an expanded specific surface area and an increased count of adsorption sites but also significantly improves the COF’s photosensitivity and the capability for charge carrier separation. Furthermore, the core of the synergistic effect between adsorption and photocatalysis lies in the ability of photocatalysis to substantially augment the adsorption process.

Waste Polyethylene-Derived Carbon Dots: Administration of Metal-Free Oxidizing Agents for Tunable Properties and Photocatalytic Hyperactivity.

The possibility of converting waste plastics into carbon dots (CDs) with 100% efficiencies using KMnO4 has emerged as a significant discovery in mitigating plastic pollution and upcycling. However, the lack of tunability of their properties, viz. aerial O2 harvesting, light-induced autophagy, and photoactivity using air as a free oxidant, has remained a bottleneck. Besides, the toxicity of KMnO4 makes the process less sustainable. Attempting to bridge these gaps, herein, we demonstrate the preparation of CDs using polyethylene with enormous controllability of their properties by utilizing less-toxic and metal-residue-free oxidizers, e.g., H2O2, HNO3, HClO4, and NaClO. We obtain structurally diverse CDs with controllable luminescent quantum yields (∼0.5-8%), excitonic lifetimes (1.3-2.3 ns), and binding energies (147-290 meV). These CDs exhibit a hugely extended range of molecular O2 harvesting (∼405-650 μM) with different amounts of strongly and weakly surface-bound O2 molecules within an estimated ratio of ∼0.77-2.51. Autophagy varied from 14 days to a nearly "no-autophagy" show. We efficiently utilized their oxygen harvesting and photocatalytic abilities to synthesize imine compounds from the corresponding amines in the open air (rate constant of ∼0.055 min-1), surpassing the literature efficiencies achieved using an O2 flow and noble metals. Notably, due to oxygen harvesting by CDs, no additional rate enhancement was observed after O2 purging, establishing the role of CDs in making free air an excellent oxidizing agent.