High photocatalytic yield in the non-oxidative coupling of methane using a Pd–TiO2 nanomembrane gas flow-through reactor† † Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ey00112e
Ontology highlight
ABSTRACT:
SUBMITTER: Longo V
PROVIDER: S-EPMC11375953 | biostudies-literature | 2024 Jul
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:The photocatalytic oxidative coupling of methane (OCM) on metal-loaded one-dimensional TiO2 nanowires (TiO2 NWs) was performed. With metal loading, the electric and optical properties of TiO2 NWs were adjusted, contributing to the improvement of the activity and selectivity of the OCM reaction. In the photocatalytic OCM reaction, the 1.0 Au/TiO2 NW catalyst exhibits an outstanding C2H6 production rate (4901 μmol g-1 h-1) and selectivity (70%), alongside the minor production of C3H8 and C2H4, achieving a total C2-C3 hydrocarbon selectivity of 75%. In contrast, catalysts loaded with Ag, Pd, and Pt show significantly lower activity, with Pt/TiO2 NWs producing only CO2, indicating a propensity for the deep oxidation of methane. The O2-TPD analyses reveal that Au facilitates mild O2 adsorption and activation, whereas Pt triggers excessive oxidation. Spectroscopic and kinetic studies demonstrate that Au loading not only enhances the separation efficiency of photogenerated electron-hole pairs, but also promotes the generation of active oxygen species in moderate amounts, which facilitates the formation of methyl radicals and their coupling into C2H6 while suppressing over-oxidation to CO2. This work provides novel insights and design strategies for developing efficient photocatalysts.
| S-EPMC11767848 | biostudies-literature
Project description:Photocatalytic methane oxidation under mild conditions using single-atom catalysts remains an advanced technology. In this work, gold single atoms (Au SAs) were introduced onto TiO2 nanostructures using a simple method. The resulting performance demonstrated effective conversion of methane into H2 and C2 products at room temperature. The as-synthesized Au SA/TiO2 exhibited a high hydrogen production rate of 2190 μmol g-1, with selectivity reaching up to 58% under optimized conditions. The methane oxidation mechanism was investigated, revealing a methyl radical pathway for generating value-added chemicals. This research provides a strategy for photocatalytic methane conversion over single-atom-supported photocatalysts.
| S-EPMC11770591 | biostudies-literature
Project description:The photocatalytic production of hydrogen using biopolymer-immobilized titanium dioxide (TiO2) is an innovative and sustainable approach to renewable energy generation. TiO2, a well-known photocatalyst, benefits from immobilization on biopolymers due to its environmental friendliness, abundance, and biodegradability. In another way, to boost the efficiency of TiO2, its surface properties can be modified by incorporating co-catalysts like platinum (Pt) to improve charge separation. In this work, the surface of commercial TiO2 PC500 was modified with Pt nanoparticles (Pt1%@PC500) and then immobilized on glass surfaces using polyhydroxyalkanoate biopolymer poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBH). The as-prepared immobilized Pt-modified TiO2 photocatalysts were fully characterized using various physicochemical techniques. The photocatalytic activity of the photocatalyst film was investigated for photocatalytic hydrogen production through water reduction using ethanol as a sacrificial donor. The impact of the film preparation conditions, e.g., PHBH concentration, PHBH:catalyst ratio, and temperature, on activity and stability was studied in detail. The application of biopolymer PHBH as a binder provides a green alternative to conventional immobilization methods, and with the application of PHBH, a stable and active photocatalyst film that showed lower activity compared to that of the suspended photocatalyst but good recyclability in six runs was prepared. A long-term photocatalytic hydrogen production experiment was carried out. In 98 h of operation, 12 mmol of hydrogen was produced in three consecutive runs with a PHBH/Pt1%@PC500 film having an area of ∼5.3 cm2. A significantly lower hydrogen productivity was observed after the first run, possibly due to a change in film structure, but thereafter, the productivity remained almost constant for the second and third runs. Hydrogen was the main product in the gas phase (90%), but carbon dioxide (4-5%) and methane (4-5%) were obtained as important byproducts. The byproducts are a consequence of the use of the sacrificial reagent ethanol. The results of the film performance are very promising, with regard to large-scale continuous hydrogen production.
| S-EPMC11636239 | biostudies-literature
Project description:This study focused on the preparation and investigation of g-C3N4/TiO2 photocatalysts using different TiO2 morphologies (anatase nanoparticles (TPs), poorly crystalline nanotubes (aTTs), and well-crystalline anatase nanorods (TRs)) and self-synthesized g-C3N4 (CN). The synthesis of the g-C3N4/TiO2 composites was carried out using a mortar mixing technique and a g-C3N4 to TiO2 weight ratio of 1:1. In addition, the g-C3N4/TiO2 composites were annealed in a muffle furnace at 350 °C for 2 h in air. The successful formation of a g-C3N4/TiO2 composite with a mesoporous structure was confirmed using the results of XRD, N2 physisorption, and FTIR analyses, while the results of microscopic analysis techniques confirmed the preservation of TiO2 morphology in all g-C3N4/TiO2 composites investigated. UV-Vis DR measurements showed that the investigated g-C3N4/TiO2 composites exhibited visible-light absorption due to the presence of CN. The results of solid-state photoluminescence and electrochemical impedance spectroscopy showed that the composites exhibited a lower charge recombination compared to pure TiO2 and CN. For example, the charge transfer resistance (RCT) of the CNTR/2 composite of TR and CN calcined in air for 2 h was significantly reduced to 0.4 MΩ, compared to 0.9 MΩ for pure TR and 1.0 MΩ for pure CN. The CNTR/2 composite showed the highest photocatalytic performance of the materials tested, achieving 30.3% degradation and 25.4% mineralization of bisphenol A (BPA) dissolved in water under visible-light illumination. In comparison, the pure TiO2 and CN components achieved significantly lower BPA degradation rates (between 2.4 and 11.4%) and mineralization levels (between 0.6 and 7.8%). This was due to (i) the presence of Ti3+ and O-vacancies in the TR, (ii) enhanced heterojunction formation, and (iii) charge transfer dynamics enabled by a dual mixed type-II/Z scheme mechanism.
| S-EPMC11820781 | biostudies-literature
Project description:In this study, we report the degradation of smooth and rough lipopolysaccharides (LPS) from Gram-negative bacteria and of lipoteichoic acid (LTA) from Gram-positive bacteria by peptide-coated TiO2 nanoparticles (TiO2 NPs). While bare TiO2 NPs displayed minor binding to both LPS and LTA, coating TiO2 NPs with the antimicrobial peptide LL-37 dramatically increased the level of binding to both LPS and LTA, decorating these uniformly. Importantly, peptide coating did not suppress reactive oxygen species generation of TiO2 NPs; hence, UV illumination triggered pronounced degradation of LPS and LTA by peptide-coated TiO2 NPs. Structural consequences of oxidative degradation were examined by neutron reflectometry for smooth LPS, showing that degradation occurred preferentially in its outer O-antigen tails. Furthermore, cryo-TEM and light scattering showed lipopolysaccharide fragments resulting from degradation to be captured by the NP/lipopolysaccharide coaggregates. The capacity of LL-37-TiO2 NPs to capture and degrade LPS and LTA was demonstrated to be of importance for their ability to suppress lipopolysaccharide-induced activation in human monocytes at simultaneously low toxicity. Together, these results suggest that peptide-coated photocatalytic NPs offer opportunities for the confinement of infection and inflammation.
| S-EPMC11551910 | biostudies-literature
Project description:Using sunlight as the driving force for photocatalytic processes holds great promise for sustainability. As a starting point for developing a material capable of degrading aquatic pollutants using solar energy as a stimulus, this work focuses on synthesizing Au-TiO2 nanocomposites using the deposition-precipitation method. Characterization of Au-TiO2 nanoparticles was performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission Electron Microscopy (TEM). A model pollutant, paracetamol, was used to test the synergetic effect of Au (0.05 wt%) nanoparticles (NPs) with TiO2 on photocatalytic activity. The influence of the parameters pH, loading (0.4, 0.8, and 1 g/L), pollutant concentration (20, 30, 40 ppm), and contact time (30, 60, 90, 120, 150, and 180 min) was studied by exposing the NPs to solar radiation. The photocatalytic degradation was most effective at a contact time of 3 h, an initial concentration of 20 ppm, and a pH of 6.8. Under these conditions, paracetamol in 1 g/L of Au-TiO2 nanocomposites can be degraded by more than 99.17% under solar irradiation. As a result of the Au-TiO2 composite's ability to successfully serve as a photocatalyst using sun radiation, water purification processes can be more widespread, cost-effective, and environmentally friendly.
| S-EPMC11901493 | biostudies-literature
Project description:Additive Manufacturing (AM) was evaluated as a promising technology for constructing photocatalytic reactors due to its inherent ability to produce complex geometries with high precision and customization. In this work, a 3D structure was designed to achieve a good light distribution inside a cylindrical batch reactor and printed using the stereolithography (SLA) technique. A hybrid material composed of a commercial photoreactive resin (Formlabs Clear V4) and the benchmark photocatalyst TiO2 P25 Evonik (1 wt%) was prepared and characterized by scanning electron microscopy (SEM) and rheological and mechanical methods. To evaluate the photocatalytic activity of the materials, several experiments on the photocatalytic degradation of Rhodamine B (RhB) were carried out using the 3D printed structure. Its performance was assessed by monitoring the concentration at specific times. Overall, the results demonstrate a simple, cost-effective, and fast technique to immobilize catalysts used in photocatalytic applications.
| S-EPMC11755327 | biostudies-literature
Project description:TiO2/MXene heterostructure has garnered significant interest as a photocatalyst due to its large surface area and efficient charge carrier separation at the interface. However, current synthesis methods produce TiO2 without clear crystal faceting and often require complicated postprocessing step, limiting its practical applications. We demonstrate a facile and controlled microwave-assisted hydrothermal synthesis for transforming multilayered Ti3CN MXene to a truncated-bipyramidal TiO2/Ti3CN heterostructure. The resulting TiO2 nanocrystals at the Ti3CN surface exhibited crystalline anatase truncated bipyramids, exposing {001} and {101} facets. We further tailored an indirect optical band gap of the TiO2/Ti3CN heterostructure in the range of 3.17-3.23 eV by varying the hydrothermal synthesis time from 15 min to 5 h at a fixed temperature of 160 °C. Efficient charge separation allowed us to decompose 97% of methylene blue (MB) within 30 min of ultraviolet (UV) light irradiation, ∼3.9-fold faster than the benchmark P25, higher than any other TiO2/MXene heterostructures. With simulated white light, we achieved over 60% efficiency of the dye decomposition within 2 h of irradiation, which resulted in 1.5-fold faster kinetics than P25. We also observed a similar excellent performance of Ti3CN-derived TiO2 in decomposing various persistent synthetic dyes, including commercial textile dye, methyl orange, and rhodamine B. In conclusion, our study provides a strategy for utilizing MXene chemical reactivity to produce highly crystalline optically active TiO2/Ti3CN heterostructure. The developed heterostructure can serve as an efficient photocatalyst for the degradation of organic pollutants.
| S-EPMC11483757 | biostudies-literature
Project description:Recently, the use of Pt in the form of single atoms (SA) has attracted considerable attention to promote the cathodic hydrogen production reaction from water in electrochemical or photocatalytic settings. First, produce suitable electrodes by Pt SA deposition on Direct current (DC)-sputter deposited titania (TiO2) layers on graphene-these electrodes allow to characterization of the electrochemical properties of Pt single atoms and their investigation in high-resolution HAADF-STEM. For Pt SAs loaded on TiO2, electrochemical H2 evolution shows only a very small overpotential. Concurrent with the onset of H2 evolution, agglomeration of the Pt SAs to clusters or nanoparticles (NPs) occurs. Potential cycling can be used to control SA agglomeration to variable-size NPs. The electrochemical activity of the electrode is directly related to the SA surface density (up to reaching the activity level of a plain Pt sheet). In contrast, for photocatalytic H2 generation already a minimum SA density is sufficient to reach control by photogenerated charge carriers. In electrochemical and photocatalytic approaches a typical TOF of ≈100-150 H2 molecules per second per site can be reached. Overall, the work illustrates a straightforward approach for reliable electrochemical and photoelectrochemical investigations of SAs and discusses the extraction of critical electrochemical factors of Pt SAs on titania electrodes.
| S-EPMC11579980 | biostudies-literature
Project description:Water pollution, resulting from industrial effluents, agricultural runoff, and pharmaceutical residues, poses serious threats to ecosystems and human health, highlighting the need for innovative approaches to effective remediation, particularly for non-biodegradable emerging pollutants. This research work explores the influence of shape-controlled nanocrystalline titanium dioxide (TiO2 NC), synthesized by a simple hydrothermal method, on the photodegradation efficiency of three different classes of emerging environmental pollutants: phenol, pesticides (methomyl), and drugs (sodium diclofenac). Experiments were conducted to assess the influence of the water matrix on treatment efficiency by using ultrapure water and stormwater (basic) collected from an urban drainage system as matrices. The size and shape of the nano-cuboids were accurately controlled during synthesis to assess their impact on photoactivity and selectivity. Regarding total organic carbon removal using TiO2 nano-cuboids in basic environments, the results were particularly remarkable. TiO2 nano-cuboids and truncated bipyramids synthesized in the 200-250 °C temperature range showed an enhanced photocatalytic efficiency when compared to alternative formulations. Diclofenac, methomyl, and phenol were fully mineralized from ultrapure water and basic stormwater. The TiO2 nano-cuboids/nano-bipyramids demonstrated better selectivity and photoactivity in comparison to irregular TiO2 nanoparticles. The differences in photoactivity and selectivity are explained in terms of charge carrier separation and trapping on the different crystal facets. Their performance demonstrates their potential as sustainable materials for the photodegradation of emerging pollutants in various water matrices.
| S-EPMC11767330 | biostudies-literature