Abatement of volatile organic compounds employing a thermoplastic nano‐photocatalyst layered on a glass reactor

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Abatement of volatile organic compounds employing a thermoplastic nano-photocatalyst layered on a glass reactor

Volatile Organic Compounds (VOCs) represent a wide class of dangerous pollutants. Here, a new gas-flow photoreactor coated with a thermoplastic TiO2-based nanocomposite is developed and used in the solar-triggered photocatalytic degradation of common VOCs. The peculiar design of the reactor combined with the features of the coating nanosystem provides a cheap and efficient way to boost the abatement of VOCs.


Abstract

Industrial development and urbanization have increased the emission of Volatile Organic Compounds (VOCs) into the atmosphere, causing environmental and health risks. Several approaches are used for their abatement, including chemical, thermo- and photo-catalytic oxidations, but they are not fully satisfactory. In this work, a thermoplastic TiO2-based photo-catalyst was used as a coating layer of a glass-reactor. Solar-triggered photocatalytic degradation of ethanol, toluene, and acetone (used as model VOCs) highlights the better performance of the coated photoreactor than that of TiO2 nanopowder. The influence of the pollutant flow rate on the photodegradation performance of the system was also investigated, revealing an inverse relationship between degradation and flow rates. The experimental data suggest that our approach provides a cost-effective and efficient way to boost the abatement of VOCs, useful for further industrial-scale applications. The morphology and the compositional homogeneity of the nanocomposite coating were addressed through Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Analysis.

Computational Modelling and Mechanistic Insight into Light‐Driven CO Dissociation of Square‐Planar Rhodium(I) Complexes

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Computational Modelling and Mechanistic Insight into Light-Driven CO Dissociation of Square-Planar Rhodium(I) Complexes

C−H activation: Rh-phosphine complexes can activate C−H bonds in otherwise unreactive alkanes. Quantum chemical calculations provide mechanistic insights into the generation of the active species which is formed via the light-induced CO dissociation at Rh(I) complexes featuring trimethylphosphine and 1,2-bis(dimethylphosphino)ethane. The calculations align well with experimental photochemical studies on the Rh(I) complexes.


Abstract

The activation step of Vaska-type Rh(I) complexes, such as the photocleavage of the Rh−CO bond, plays an important role in the subsequent C−H activation. To elucidate the details of the photochemistry of Vaska-type Rh(I) complexes, such as trans-Rh(PMe3)2(CO)(Cl), we here present a computationally derived picture as obtained at the density functional level of theory in combination with multireference wavefunction-based methods. We have identified that the photocleavage of CO proceeds via the metal-centered excited state (3MC, ), which is populated through intersystem crossing from the dipole-allowed excited state S1( - ). Moreover, the present study unraveled the reasons for the low C−H activation efficiency when using Rh featuring the bidentate ligand 1,2-bis(dimethylphosphino)ethane (dmpe), namely due to its unfavorable photochemical properties, i. e., the small driving force for light-induced CO loss and the fast deactivation of 3MC state back to the singlet ground state. In this study, we provide theoretical insight into mechanistic details underlying the light-induced CO dissociation process, for Rh complexes featuring PMe3 and dmpe ligands.

Organic fluorophores with large Stokes shift for bioimaging and biosensing

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Organic fluorophores with large Stokes shift for bioimaging and biosensing

The review has systematically summarized several methods recently developed to increase Stokes shift of fluorophores by structural modification, and highlighted typical applications of fluorophores with large Stokes shift in single-excitation multi-color imaging and ratiometric imaging. The review will provide a theoretical guidance for the design of novel fluorophores with large Stokes shift.


Abstract

Fluorophores and fluorophores-based probes or labels can visualize the structures and content fluctuations of biomolecules, and have made great progress in the broad range of biomedicine fields. However, many commercially available fluorophores suffer from small Stokes shift, which results in insufficient signal-to-noise ratio and self-quenching in advanced imaging techniques. Moreover, the small Stokes shift also hinders the application of fluorophores in some complex imaging, such as single-excitation multicolor imaging. In the past two decades, many effects have been made to enlarge Stokes shift of fluorophores. In this review, we clarified the reasons for the small Stokes shift building on the structural analysis of fluorophores, systematically summarize the methods of structural modification to increase Stokes shift, and present some representative applications of fluorophores with large Stokes shift in imaging and sensing.

Syngas Production by Chemical Looping Dry Reforming of Methane over Ni‐modified MoO3/ZrO2

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Syngas Production by Chemical Looping Dry Reforming of Methane over Ni-modified MoO3/ZrO2

Ni-modified molybdenum zirconia (Ni/MoO3/ZrO2) was developed as an effective oxygen storage material for chemical looping dry reforming of methane (CL–DRM) under isothermal reaction conditions of 650 °C, which was 100–200 °C lower than the previously reported oxide-based materials.


Abstract

We investigated supported-MoO3 materials effective for the chemical looping dry reforming of methane (CL–DRM) to decrease the reaction temperature. Ni-modified molybdenum zirconia (Ni/MoO3/ZrO2) showed CL–DRM activity under isothermal reaction conditions of 650 °C, which was 100–200 °C lower than the previously reported oxide-based materials. Ni/MoO3/ZrO2 activity strongly depends on the MoO3 loading amount. The optimal loading amount was 9.0 wt.% (Ni/MoO3(9.0)/ZrO2), wherein two-dimensional polymolybdate species were dominantly formed. Increasing the loading amount to more than 12.0 wt.% resulted in a loss of activity owing to the formation of bulk Zr(MoO4)2 and/or MoO3. In situ Mo K-edge XANES studies revealed that the surface polymolybdate species serve as oxygen storage sites. The Mo6+ species were reduced to Mo4+ species by CH4 to produce CO and H2. The reduced Mo species reoxidized by CO2 with the concomitant formation of CO. The developed Ni/MoO3(9.0)/ZrO2 was applied to the long-term CL–DRM under high concentration conditions (20 % CH4 and 20 % CO2) at 650 °C, with two pathways possible for converting CH4 and CO2 to CO and H2 via the redox reaction of the Mo species and coke formation.