Photocatalytic Oxidation Research Articles

Photocatalytic Oxidation of Benzene to Phenol with O2 over WO3 Treated by Vacuum-Sealed Annealing.

Photocatalytic oxidation of benzene to phenol using molecular O2 is one of the most promising sustainable approaches for the green synthesis of phenol. Introducing oxygen vacancies (OVs) on semiconductor surfaces by defect engineering is a promising strategy to enhance the efficiency of benzene oxidation to produce phenol due to the unique functions of OVs in facilitating the charge separation and activation of molecular O2. Herein, a vacuum-sealed annealing strategy has been well developed to generate abundant surface OVs on semiconductors, such as WO3. The well-sealed quartz vial creates a well-controlled low-pressure condition for the formation of OVs without the need for external energy for maintaining the vacuum state. Moreover, the gaseous species generated during the thermal annealing process help mitigate stress-induced defects, particularly bulk defects. The vacuum-sealed annealed WO3 with sufficient OVs and reduced bulk defects shows a better photocatalytic performance in the one-step oxidation of benzene to phenol with O2, compared to the WO3 synthesized through thermal annealing in Ar and H2 atmospheres. The present vacuum-sealed annealing strategy is found to be further applicable to engineer a wide range of semiconducting photocatalysts with abundant OVs to optimize their properties for efficient photocatalysis and other OV-promoted systems.

Integrating Two Photochromics into One Three-Dimensional Covalent Organic Framework for Synergistically Enhancing Multiple Photocatalytic Oxidations.

While photocatalytic oxidations are a category of important reactions in wide chemical synthesis, the fabrication of effective photocatalysts for broad oxidation reactions is still of a great challenge. Herein, by rationally integrating two photochromics, porphyrin and triphenylamine, a three-dimensional photoactive covalent organic framework (COF) is successfully constructed for photocatalytic oxidations. Characterization studies not only show the formation of a crystalline and three-dimensional porous framework, but also reveal its effective photochemical semiconductor properties derived from the porphyrin and triphenylamine moieties. Electron paramagnetic resonance measurements indicate that the COF is an effective photocatalyst for the generation of both singlet oxygen (1O2) and superoxide radical anions (·O2-). Synergistically enhanced efficiency in all photocatalytic reactions of photocatalytic aerobic oxidation of alkylbenzenes and silanes as well as thioanisoles, and cross-dehydrogenative coupling reaction of N-phenyltetrahydroisoquinoline and indole is confirmed by both experimental and theoretical studies, demonstrating its promising potential for broad photocatalytic oxidation reactions.

Integrating Two Photochromics into One Three‐Dimensional Covalent Organic Framework for Synergistically Enhancing Multiple Photocatalytic Oxidations

While photocatalytic oxidations are a category of important reactions in wide chemical synthesis, the fabrication of effective photocatalysts for broad oxidation reactions is still of a great challenge. Herein, by rationally integrating two photochromics, porphyrin and triphenylamine, a three‐dimensional photoactive covalent organic framework (COF) is successfully constructed for photocatalytic oxidations. Characterization studies not only show the formation of a crystalline and three‐dimensional porous framework, but also reveal its effective photochemical semiconductor properties derived from the porphyrin and triphenylamine moieties. Electron paramagnetic resonance measurements indicate that the COF is an effective photocatalyst for the generation of both singlet oxygen (1O2) and superoxide radical anions (·O2−). Synergistically enhanced efficiency in all photocatalytic reactions of photocatalytic aerobic oxidation of alkylbenzenes and silanes as well as thioanisoles, and cross‐dehydrogenative coupling reaction of N‐phenyltetrahydroisoquinoline and indole is confirmed by both experimental and theoretical studies, demonstrating its promising potential for broad photocatalytic oxidation reactions.

Unveiling the green synthesis of WO3 nanoparticles by using beetroot (Beta vulgaris) extract for photocatalytic oxidation of rhodamine B.

Tungsten oxide (WO3) nanoparticles (WO3NPs) were prepared using beetroot (Beta vulgaris) extract. The synthesis was optimized by evaluating the effect of pH during the reduction of the WO3 precursor and sintering temperature. Physicochemical characterization of the formed nanoparticles was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance UV-visible spectroscopy. Furthermore, the prepared WO3NPs were employed as photocatalyst for rhodamine B removal over the photocatalytic oxidation mechanism. Synthesis optimization revealed that a single phase of WO3NPs obtained by reduction at pH 4 and a sintering temperature of 550°C. XRD and XPS measurements revealed that the single-phase WO3NPs was obtained with a crystallite size of 26.4nm. SEM and transmission electron microscopy (TEM) indicated polymorphic forms, predominantly as nanorods, with a mean particle size of 24nm. The WO3NPs have a band gap energy of 2.9eV, supporting their performance as a photocatalyst. Evaluation of the photocatalytic activities of WO3NPs represents high activity and reusability of the material. A removal efficiency of 99.67% was achieved during 30min of treatment under UV light illumination. A study on the effect of scavengers revealed the important role of hydroxy radicals in the photocatalysis mechanism. WO3NPs can be recycled and reused for photocatalysis, maintaining photoactivity for five cycles.

Effect of surface iodine atom on dissolved oxygen activation for enhanced photocatalytic advanced oxidation processes over Bi2WO6 nanosheet

Effect of surface iodine atom on dissolved oxygen activation for enhanced photocatalytic advanced oxidation processes over Bi2WO6 nanosheet

Efficient photocatalytic oxidation of cyclohexane to KA oil by carbon nitride hybridized decatungstate under visible light

Efficient photocatalytic oxidation of cyclohexane to KA oil by carbon nitride hybridized decatungstate under visible light

Lewis and Brønsted Acids Synergy in Photocatalytic Aerobic Alcohol Oxidations

Lewis and Brønsted Acids Synergy in Photocatalytic Aerobic Alcohol Oxidations

Lewis and Brønsted Acids Synergy in Photocatalytic Aerobic Alcohol Oxidations.

Photocatalytic chemical transformations for green organic synthesis has attracted much interest. However, their development is greatly hampered by the lack of sufficient reactive sites on the photocatalyst surface for the adsorption and activation of substrate molecules. Herein, we demonstrate that the introduction of well-defined Lewis and Brønsted acid sites coexisting on the surface of TiO2 (SO42-/N-TiO2) creates abundant active adsorption sites for photoredox reactions. The electron-deficient Lewis acid sites supply coordinatively unsaturated surface sites to adsorb molecular oxygen, and the Brønsted acid sites are liable to donate protons to form hydrogen bonds with the OH groups of alcohols like benzyl alcohol (BA). These coexistent acid sites result in a strong synergistic effect in photocatalytic aerobic oxidation of BA. For example, the conversion of BA to benzaldehyde was found to be 88.6%, being much higher than those of pristine TiO2 (14.7%), N-doped TiO2 (N-TiO2, 24.6%), sulfated TiO2 (SO42-/ TiO2, 35.4%), and even their sum. The apparent quantum efficiency (AQE) was determined to be 58.1% at 365 nm and 12.9% at 420 nm over SO42-/N-TiO2. This strategy to create effective synergistic Lewis and Brønsted acids on the catalyst surfaces enables us to apply it to other semiconducting photocatalytic organic transformations.

P-356. Reduction of high-touch surface aerobic bacteria and fungi colony counts with the implementation of ActivePure continuous disinfection technology

Abstract Background As hospitals nationwide rebound from the effects of the COVID pandemic, reduced staffing and increased hospital-acquired infections (HAIs) are still challenges. Surface disinfection plays a pivotal role in the prevention of HAIs. To improve high-touch surface disinfection and remove the dependence on the human factor, ActivePure continuous disinfection technology devices were installed in the Medical Intensive Care Unit (MICU) HVAC system at Ochsner LSU Health Shreveport in October 2023. ActivePure is a novel technique that kills microbes in the environment by using an advanced photocatalytic oxidation particle. Methods A prospective study was conducted in the 19-bed MICU. Two weeks before device activation, 50 high-touch surface samples and 10 reservoir samples were collected by sterile sponge in situ and plated onto Nutritive (tryptic soy) agar for total aerobic microbial counts, Selective (Sabouraud dextrose) agar for total fungal counts, selective (MeReSa) agar for total MRSA counts, and CHROMagar selective for Carbapenem-Resistant Acinetobacter baumannii (CRAB). All agar plates were incubated at 30°C or 37°C (as applicable) for 48-96 hours. For evaluation, serial dilution plate counts were used to calculate the CFU per sponge for each media type. The detection limit was 10 CFU/sponge for each evaluation. After 4 weeks post-activation, 50 high-touch surface samples and 10 reservoir samples from the same pre-activation sample locations were collected and evaluated via the same methods, and the same was repeated at 9 weeks post-activation. Routine cleaning and disinfection protocols were unchanged during the entire study period. Figure 2 Results The mean aerobic bacterial and fungi surface CFUs were reduced over 99.78% (Fig 1). The mean MRSA surface CFUs were reduced by 99.99% and the mean CRAB surface CFUs were reduced by 99.75% (Fig 2). There was a 94% reduction in surfaces with greater than 500 CFUs/100cm2 of MRSA. There was a 100% reduction in reservoirs with greater than 500 CFUs/100cm2 of CRAB and 80% reduction in reservoirs with greater than 10 CFUs/100cm2 of CRAB. Conclusion The ActivePure continuous disinfection technology devices significantly reduced total aerobic bacteria, including MRSA, difficult-to-treat CRAB, and fungi surface colony counts on high-touch surfaces. Disclosures Kimberly Trosch, RN, BSN, ActivePure Technologies: Full time employee Daniel Marsh, n/a, ActivePure Medical: Advisor/Consultant

Synergetic Atom‐Island and Metal Alloy Triggering Tandem Reaction for CH4 Photooxidation to CH3OH

AbstractCH3OH is the most desired product of photocatalytic CH4 conversion. The prominent metal‐decorated photocatalyst is challenging in both high yield and selectivity for CH3OH products due to over‐oxidation by •OH mechanism. Here, interstitial Zn is fabricated into ZniO to induce the formation of Zn atom island for rapid single electron reduction of O2 into •OOH instead of •OH for the selective combination with methyl into CH3OOH. AuPd alloy is simultaneously decorated on ZniO surface for tuning CH3OOH adsorption and reduction into CH3OH. The synergy of Zn atom island and AuPd alloy achieve a tandem reaction pathway (CH4→CH3OOH→CH3OH) for an unprecedented CH3OH yield of 2444 mmol gAuPd−1 h−1 (or 8800 µmol gcat−1 h−1) with 98.3% selectivity, which bypasses the •OH mechanism for tuning the high selectivity of CH3OH. An apparent quantum efficiency of 18.53% at 370 nm for CH4 conversion are super to the reported photocatalytic systems. Thus, this work provides the new strategy of the synergetic atom island and metal alloy photocatalysts through a tandem reaction pathway to mediate the photocatalytic selective oxidation of CH4 into the desired CH3OH.

Photocatalytic Oxidation of Sulfides in Water Using a Donor–Acceptor-Based Porous Organic Polymer

Photocatalytic Oxidation of Sulfides in Water Using a Donor–Acceptor-Based Porous Organic Polymer

Photoredox-Mediated Immunotherapy Utilizing Rhenium(I) Photocatalysts with Electron Donor-Acceptor-Donor Configuration.

The hypoxic environment of solid tumors significantly diminishes the therapeutic efficacy of oxygen-dependent photodynamic therapy. Developing efficient photosensitizers that operate via photoredox catalysis presents a promising strategy to overcome this challenge. Herein, we report the rational design of two rhenium(I) tricarbonyl complexes (Re-TPO and Re-TP) with electron donor-acceptor-donor configuration. Notably, Re-TP exhibits aggregation-induced emission properties and enhanced spin-orbit coupling compared to Re-TPO, thus exhibiting promoted photosensitizing capability. In addition to generating type I and II reactive oxygen species, the excited Re-TP facilitates the photocatalytic oxidation of NADH to NAD+ and the photoreduction of pyruvic acid to lactic acid. This metabolic intervention triggers PD-L1-linked immune responses and disrupts tumor redox balance, leading to ferroptosis and immunogenic cell death. The combined ferroptosis and immunotherapy effects significantly suppress both primary and distant B16 tumors. This investigation provides a compelling model for designing efficient metal-based PSs for photoredox-mediated photoimmunotherapy against hypoxic tumors.

Synchronous Photocatalytic Redox Conversion of Chromium(VI) and Arsenic(III) by Bimetallic Fe/Ti Metal-Organic Frameworks.

In this work, bimetallic organic frameworks NH2-MOFs(Fe, Ti) with different Fe3+/Ti4+ molar ratios were prepared by a hydrothermal method for the synchronous redox transformation of Cr(VI) and As(III). These results showed that NH2-MIL-125(Ti) was less effective in the photocatalytic removal of Cr(VI), whereas NH2-MIL-88B(Fe) was less effective in the photocatalytic oxidative removal of As(III). Due to the introduction of Fe3+, the photocatalytic reduction removal of Cr(VI) (23.04 → 42.56%) and the photocatalytic oxidation removal of As(III) (5.58 → 26.09%) by NH2-MOFs(Fe, Ti) were significantly enhanced. Among them, NH2-MIL-88B(Fe0.6Ti0.4) exhibited the best performance in the photoreduction of Cr(VI) and photo-oxidation of As(III), which balanced the insufficiency of monometallic MOFs(Fe/Ti). In this case, the total removal of Cr(VI) and As(III) by NH2-MIL-88B(Fe0.6Ti0.4) was found to be 94.19 and 83.54%, respectively. The excellent photocatalytic property could account for the ligand-to-metal charge transfer (LMCT), where photogenerated e- generated by -NH2 group excitation was transferred to the active site Fe-O clusters, as well as e- transported along Ti → O → Fe (metal-to-metal charge transfer, MMCT). Therefore, the synergetic effect of LMCT and MMCT could efficiently inhibit the recombination of e--h+ pairs, improving the photocatalytic performance of NH2-MOFs(Fe, Ti).

Constructing a Polyoxometalate-Based Metal-Organic Framework for Photocatalytic Oxidation of Thioethers to Sulfoxides Utilizing In Situ-Generated Superoxide Radicals.

Developing new photocatalysts for the selective oxidation of thioethers to high-value-added sulfoxides under low-oxygen mild conditions is a promising but challenging strategy. Here, a new polyoxometalate-based metal-organic framework (POMOF), CoBW12-TPT, was successfully synthesized, wherein continuous π···π stacking interactions and direct coordination bonds not only strengthen the framework's stability but also accelerate electron transfer. A series of experiments and theoretical studies, including control experiments, kinetic studies, electrochemical spectroscopic analyses, and electron paramagnetic resonance, revealed the synergistic catalytic effect among Co(II) metal centers, BW12O405-, and the photosensitizer TPT. CoBW12-TPT was applied in the photocatalytic oxidation of thioethers to sulfoxides. Under irradiation, the photoinduced electron transfer of POMOF leads to the generation of superoxide radicals from O2, which controls the selective generation of sulfoxide compounds in the photocatalytic desulfurization reaction and shows good activity. In particular, it can be applied to the construction of some drug molecules such as Modafinil and Albendazole Oxide.

Factors affecting iron and manganese dissolution in groundwater: treatments with simultaneous oxidation and precipitation methods

ABSTRACT This study explores variations in groundwater (GW) pH, conductivity, ammonium, iron, and manganese parameters to reveal prospective interactions having an impact on the dissolved metal concentrations. To this end, bivariate and partial correlation procedures were applied to the data to obtain incisive evaluation. Besides characterisation efforts, photocatalytic iron and manganese removal experiments were also carried out with Ni-doped TiO2 nano-composite thin films (TFs) on real GW samples. UV-A (365 nm) An LED array was used as the illumination source. The experimental setup was based on three treatment routes including photocatalytic oxidation (PCO), NaOH-aided precipitation and PCO with simultaneous precipitation (SPCO-P). The main statistical analysis and treatment efforts have been performed on data and samples of a single well, respectively (N = 15). However, extended statistical analysis has also been performed on larger data groups (N = 1366) obtained from different GW sources as well. Analytical results have revealed that about 90% of iron and manganese were in oxidised forms which do not precipitate by simple pH regulation. Statistical analysis has also revealed significant interactions between metal concentrations and observed parameters depending on the level of pH and conductivity. Furthermore, the SPCO-P strategy has provided a four-fold increase in reaction rate (pseudo-first-order, kobs: 0.04 min−1). Removal efficiencies of iron and manganese also increased from 10% to 96% – 85%, respectively.

Passivating Lattice Oxygen in ZnO Nanocrystals to Reduce its Interactions with the Key Intermediates for a Selective Photocatalytic Methane Oxidation to Methanol

An inevitable overoxidation process is considered as one of the most challenging problems in the direct conversion of methane (CH4) to methanol (CH3OH), which is limited by the uncontrollable cracking of key intermediates. Herein, we have successfully constructed a photocatalyst, the Fe‐doped ZnO hollow polyhedron (Fe/ZnOHP), for the highly selective photoconversion of CH4 to CH3OH under mild conditions. In‐situ experiments and density functional theory calculations confirmed that the introduction of Fe was able to decrease the energy level of the O 2p orbital, which passivated the activity of lattice oxygen in ZnO nanocrystals. This passivation effect greatly weakened the interaction between *CH3 and lattice oxygen, thus facilitating the conversion of *CH3O to *CH3 intermediate rather than the direct desorption of *CH3O. As a result, Fe/ZnOHP exhibited excellent CH3OH generation rate (ca. 1009 μmol gcat−1 h‐1) and selectivity (ca. 96%) in the photocatalytic conversion of CH4 at room temperature and low pressure.

Passivating Lattice Oxygen in ZnO Nanocrystals to Reduce its Interactions with the Key Intermediates for a Selective Photocatalytic Methane Oxidation to Methanol.

Aninevitable overoxidation process is considered as one of the most challenging problems in the direct conversion of methane (CH4) to methanol (CH3OH), which is limited by the uncontrollable cracking of key intermediates. Herein, we have successfully constructed a photocatalyst, the Fe-doped ZnO hollow polyhedron (Fe/ZnOHP), for the highly selective photoconversion of CH4 to CH3OH under mild conditions.In-situ experiments and density functional theory calculations confirmed that the introduction of Fe was able to decrease the energy level of the O 2p orbital, which passivated the activity of lattice oxygen in ZnO nanocrystals. This passivation effect greatly weakened the interaction between *CH3 and lattice oxygen, thus facilitating the conversion of *CH3O to *CH3 intermediate rather than the direct desorption of *CH3O. As a result, Fe/ZnOHP exhibited excellent CH3OH generation rate (ca. 1009 μmol gcat-1 h-1) and selectivity (ca. 96%) in the photocatalytic conversion of CH4 at room temperature and low pressure.

Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde with the Participation of Crystalline Carbon Nitride Doped with Oxygen

Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde with the Participation of Crystalline Carbon Nitride Doped with Oxygen

Zeolite Encapsulation to Enhance Interfacial Gas Availability for Photocatalytic Hydrogen Peroxide Production

AbstractThe photocatalytic oxidation of water with gaseous oxygen is environmentally benign for the synthesis of hydrogen peroxide (H2O2), but it is currently constrained by the inadequate supply of gaseous oxygen at the catalyst surface in a solid–liquid–gas triple‐phase reaction system. Herein, we address this challenge by employing the zeolite encapsulated catalysts that efficiently enrich gaseous oxygen and accelerate the H2O2 synthesis in aqueous conditions. We focus on the classical titania photocatalyst, encapsulating it within siliceous MFI zeolite crystals. This encapsulation results in a significant enhancement in H2O2 synthesis efficiency, achieving a yield that is ten times greater than that with unencapsulated TiO2. Mechanism study reveals that gaseous oxygen is notably concentrated within the microporous structure of the zeolite under aqueous conditions, thereby facilitating its interaction with the titania surface at the liquid‐solid interface. In addition, the H2O2 product could swiftly transfer through the micropores, thereby reducing the side reaction of decomposition. This design provides an alternative pathway to address the poor gas solubility of gaseous reactants in water, and paves the way for advancements in various other photocatalytic processes.

Toward Maximizing the Ag–CeO2 Interface and Rich Oxygen Vacancies for Efficient Photocatalytic Oxidation of 5-Hydroxymethylfurfural

Toward Maximizing the Ag–CeO₂ Interface and Rich Oxygen Vacancies for Efficient Photocatalytic Oxidation of 5-Hydroxymethylfurfural