Timothy Koscik

Efficient photocatalytic Suzuki cross-coupling reactions on Au–Pd alloy nanoparticles under visible light irradiation

Publisher: Royal Society of Chemistry (RSC)

Date: 26-06-2014

DOI: 10.1039/C4GC00588K

Visible light enhanced oxidant free dehydrogenation of aromatic alcohols using Au-Pd alloy nanoparticle catalysts

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C3GC41866A

Enhancing Catalytic Performance of Palladium in Gold and Palladium Alloy Nanoparticles for Organic Synthesis Reactions through Visible Light Irradiation at Ambient Temperatures

Publisher: American Chemical Society (ACS)

Date: 08-04-2013

DOI: 10.1021/JA400527A

Abstract: The intrinsic catalytic activity of palladium (Pd) is significantly enhanced in gold (Au)-Pd alloy nanoparticles (NPs) under visible light irradiation at ambient temperatures. The alloy NPs strongly absorb light and efficiently enhance the conversion of several reactions, including Suzuki-Miyaura cross coupling, oxidative addition of benzylamine, selective oxidation of aromatic alcohols to corresponding aldehydes and ketones, and phenol oxidation. The Au/Pd molar ratio of the alloy NPs has an important impact on performance of the catalysts since it determines both the electronic heterogeneity and the distribution of Pd sites at the NP surface, with these two factors playing key roles in the catalytic activity. Irradiating with light produces an even more profound enhancement in the catalytic performance of the NPs. For ex le, the best conversion rate achieved thermally at 30 °C for Suzuki-Miyaura cross coupling was 37% at a Au/Pd ratio of 1:1.86, while under light illumination the yield increased to 96% under the same conditions. The catalytic activity of the alloy NPs depends on the intensity and wavelength of incident light. Light absorption due to the Localized Surface Plasmon Resonance of gold nanocrystals plays an important role in enhancing catalyst performance. We believe that the conduction electrons of the NPs gain the light absorbed energy producing energetic electrons at the surface Pd sites, which enhances the sites' intrinsic catalytic ability. These findings provide useful guidelines for designing efficient catalysts composed of alloys of a plasmonic metal and a catalytically active transition metal for various organic syntheses driven by sunlight.

Plasmonic switching of the reaction pathway: Visible-light irradiation varies the reactant concentration at the solid-solution interface of a gold-cobalt catalyst

Publisher: Wiley

Date: 18-06-2019

DOI: 10.1002/ANIE.201904452

Abstract: Product selectivity of alkyne hydroamination over catalytic Au

Surface‐Plasmon‐Enhanced Transmetalation between Copper and Palladium Nanoparticle Catalyst

Publisher: Wiley

Date: 20-04-2022

DOI: 10.1002/ANIE.202203158

Abstract: Surface‐plasmon‐mediated phenylacetylide intermediate transfer from the Cu to the Pd surface affords a novel mechanism for transmetalation, enabling wavelength‐tunable cross‐coupling and homo‐coupling reaction pathway control. C−C bond forming Sonogashira coupling and Glaser coupling reactions in O 2 atmosphere are efficiently driven by visible light over heterogeneous Cu and Pd nanoparticles as a mixed catalyst without base or other additives. The reaction pathway can be controlled by switching the excitation wavelength. Shorter wavelengths (400–500 nm) give the Glaser homo‐coupling diyne, whereas longer wavelength irradiation (500–940 nm) significantly increases the degree of cross‐coupling Sonogashira coupling products. The ratio of the activated intermediates of alkyne to the iodobenzene is wavelength dependent and this regulates transmetalation. This wavelength‐tunable reaction pathway is a novel way to optimize the product selectivity in important organic syntheses.

Variability in the analysis of a single neuroimaging dataset by many teams

Publisher: Springer Science and Business Media LLC

Date: 20-05-2020

DOI: 10.1038/S41586-020-2314-9

Photon Energy Threshold in Direct Photocatalysis with Metal Nanoparticles – Key Evidence from Action Spectrum of the Reaction

Publisher: American Chemical Society (ACS)

Date: 23-05-2017

DOI: 10.1021/ACS.JPCLETT.7B00941

Abstract: By investigating the action spectra (the relationship between the irradiation wavelength and apparent quantum efficiency of reactions under constant irradiance) of a number of reactions catalyzed by nanoparticles including plasmonic metals, nonplasmonic metals, and their alloys at near-ambient temperatures, we found that a photon energy threshold exists in each photocatalytic reaction only photons with sufficient energy (e.g., higher than the energy level of the lowest unoccupied molecular orbitals) can initiate the reactions. This energy alignment (and the photon energy threshold) is determined by various factors, including the wavelength and intensity of irradiation, molecule structure, reaction temperature, and so forth. Hence, distinct action spectra were observed in the same type of reaction catalyzed by the same catalyst due to a different substituent group, a slightly changed reaction temperature. These results indicate that photon-electron excitations, instead of the photothermal effect, play a dominant role in direct photocatalysis of metal nanoparticles for many reactions.

Direct photocatalysis of supported metal nanostructures for organic synthesis

Publisher: IOP Publishing

Date: 23-06-2017

DOI: 10.1088/1361-6463/AA73F6

Viable Photocatalysts under Solar-Spectrum Irradiation: Nonplasmonic Metal Nanoparticles

Publisher: Wiley

Date: 07-02-2014

DOI: 10.1002/ANIE.201308145

Abstract: Supported nanoparticles (NPs) of nonplasmonic transition metals (Pd, Pt, Rh, and Ir) are widely used as thermally activated catalysts for the synthesis of important organic compounds, but little is known about their photocatalytic capabilities. We discovered that irradiation with light can significantly enhance the intrinsic catalytic performance of these metal NPs at ambient temperatures for several types of reactions. These metal NPs strongly absorb the light mainly through interband electronic transitions. The excited electrons interact with the reactant molecules on the particles to accelerate these reactions. The rate of the catalyzed reaction depends on the concentration and energy of the excited electrons, which can be increased by increasing the light intensity or by reducing the irradiation wavelength. The metal NPs can also effectively couple thermal and light energy sources to more efficiently drive chemical transformations.

Enhancing visible-light photocatalytic performance of Au/TiO2 catalysts through light reflection-promoted optical absorption with oriented anatase mesocrystals

Publisher: Royal Society of Chemistry (RSC)

Date: 2023

DOI: 10.1039/D2TA09982A

Abstract: Au NPs effectively harvest light through absorption of light back-reflected from oriented TiO 2 mesocrystals supported on Ti foil. The enhanced light absorption facilitates the generation of electron–hole pairs and intensive EM fields that realizes efficient photocatalysis.

Variability in the analysis of a single neuroimaging dataset by many teams

Publisher: Cold Spring Harbor Laboratory

Date: 15-11-2019

DOI: 10.1101/843193

Abstract: Data analysis workflows in many scientific domains have become increasingly complex and flexible. To assess the impact of this flexibility on functional magnetic resonance imaging (fMRI) results, the same dataset was independently analyzed by 70 teams, testing nine ex-ante hypotheses. The flexibility of analytic approaches is exemplified by the fact that no two teams chose identical workflows to analyze the data. This flexibility resulted in sizeable variation in hypothesis test results, even for teams whose statistical maps were highly correlated at intermediate stages of their analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Importantly, meta-analytic approaches that aggregated information across teams yielded significant consensus in activated regions across teams. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset. Our findings show that analytic flexibility can have substantial effects on scientific conclusions, and demonstrate factors related to variability in fMRI. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for multiple analyses of the same data. Potential approaches to mitigate issues related to analytical variability are discussed.

University Of Arkansas For Medical Sciences

Location: United States of America

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University Of Sydney

Location: Australia

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University Of Iowa

Location: United States of America

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Max Planck Institute Of Colloids And Interfaces

Location: Germany

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Queensland University Of Technology

Location: Australia

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Tuning Non-plasmonic Metals To High Performance Photocatalysts

Start Date: 2019

End Date: 2022

Funder: Australian Research Council

Promoting Transition Metal Complex Catalysis With Plasmonic Antennae

Start Date: 2021

End Date: 2024

Funder: Australian Research Council

Scale-up Of Catalytic Furandicarboxylic Acid Production At Room Temperature

Start Date: 2022

End Date: 2024

Funder: Australian Research Council

Plasmonic Nanoparticle Catalysis For Nitrogen-based Synthesis

Start Date: 2022

End Date: 2026

Funder: Australian Research Council

Discovery Early Career Researcher Award - Grant ID: DE190101450

Start Date: 01-2019

End Date: 08-2022

Amount: $392,556.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT220100732

Start Date: 06-2023

End Date: 06-2027

Amount: $920,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP210301424

Start Date: 06-2023

End Date: 05-2025

Amount: $245,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP210103357

Start Date: 02-2021

End Date: 12-2023

Amount: $284,000.00

Funder: Australian Research Council