| 1. |
- Lalaoui, Noemie, et al.
(författare)
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Gold nanoparticle-based supramolecular approach for dye-sensitized H-2-evolving photocathodes
- 2022
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry. - 1477-9226 .- 1477-9234. ; 51:41, s. 15716-15724
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Tidskriftsartikel (refereegranskat)abstract
- Solar conversion of water into the storable energy carrier H-2 can be achieved through photoelectrochemical water splitting using light adsorbing anodes and cathodes bearing O-2 and H-2 evolving catalysts, respectively. Herein a novel photocathode nanohybrid system is reported. This photocathode consists of a dye-sensitized p-type nickel oxide (NiO) with a perylene-based chromophore (PCA) and a tetra-adamantane modified cobaloxime reduction catalyst (Co) that photo-reduces aqueous protons to H-2. An original supramolecular approach was employed, using beta-cyclodextrin functionalized gold nanoparticles (beta-CD-AuNPs) to link the alkane chain of the PCA dye to the adamantane moieties of the cobaloxime catalyst (Co). This new architecture was investigated by photoelectrochemical measurements and via femtosecond-transient absorption spectroscopy. The results show that irradiation of the complete NiO|PCA|beta-CD-AuNPs|Co electrode leads to ultrafast hole injection into NiO (pi = 3 ps) from the excited dye, followed by rapid reduction of the catalyst, and finally H-2 evolution.
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| 2. |
- Lindroth, Rickard, et al.
(författare)
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Sustainable Ir-Photoredox Catalysis by Means of Heterogenization
- 2022
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Ingår i: ACS ORGANIC & INORGANIC AU. - : American Chemical Society (ACS). - 2694-247X. ; 2:5, s. 427-432
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Tidskriftsartikel (refereegranskat)abstract
- A heterogenized iridium catalyst was employed to perform photoredox catalysis for a collection of mechanistically orthogonal reactions using very low quantities of iridium (0.01-0.1 mol %). The heterogenized construct consists of an organometallic iridium coordination complex bonded to an aluminum metal oxide solid-state support via an anchoring group. The solid-state support allows for easy recovery and reusability of the catalyst. Evaluation of the catalytic activity was performed with five different reactions, showing broad applicability and demonstrating the general potential for a heterogenized strategy. Moreover, the heterogenized catalyst was shown to be reusable up to five times and also mediated the reactions with much higher efficiency than the original processes by employing the corresponding homogeneous catalyst. As a result of the low catalyst loadings employed, the feasibility of reusage, and faster reaction times, this catalyst offers a more sustainable option when precious metal catalysts are used in organic synthesis. Finally, the catalyst was successfully applied to a gram-scale reaction, showing it is susceptible to scalability.
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| 3. |
- Materna, Kelly L., et al.
(författare)
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Photoredox Catalysis Using Heterogenized Iridium Complexes**
- 2021
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Ingår i: Chemistry - A European Journal. - : John Wiley & Sons. - 0947-6539 .- 1521-3765. ; 27:68, s. 16966-16977
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Tidskriftsartikel (refereegranskat)abstract
- Heterogenized photoredox catalysts provide a path for sustainable chemical synthesis using highly tunable, reusable constructs. Here, heterogenized iridium complexes as photoredox catalysts were assembled via covalent attachment to metal oxide surfaces (ITO, ZrO2, Al2O3) in thin film or nanopowder constructs. The goal was to understand which materials provided the most promising constructs for catalysis. To do this, reductive dehalogenation of bromoacetophenone to acetophenone was studied as a test reaction for system optimization. All catalyst constructs produced acetophenone with high conversions and yields with the fastest reactions complete in fifteen minutes using Al2O3 supports. The nanopowder catalysts resulted in faster and more efficient catalysis, while the thin film catalysts were more robust and easily reused. Importantly, the thin film constructs show promise for future photoelectrochemical and electrochemical photoredox setups. Finally, all catalysts were reusable 2-3 times, performing at least 1000 turnovers (Al2O3), demonstrating that heterogenized catalysts are a sustainable catalyst alternative.
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| 4. |
- Materna, Kelly L., et al.
(författare)
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Understanding the Performance of NiO Photocathodes with Alkyl-Derivatized Cobalt Catalysts and a Push-Pull Dye
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 12:28, s. 31372-31381
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous NiO photocathodes containing the push-pull dye PB6 and alkyl-derivatized cobaloxime catalysts were prepared using surface amide couplings and analyzed for photocatalytic proton reduction catalysis. The length of the alkyl linker used to derivatize the cobalt catalysts was found to correlate to the photocurrent with the highest photocurrent observed using shorter alkyl linkers but the lowest one for samples without linker. The alkyl linkers were also helpful in slowing dye-NiO charge recombination. Photoelectrochemical measurements and femtosecond transient absorption spectroscopic measurements suggested electron transfer to the surfaceimmobilized catalysts occurred; however, H-2 evolution was not observed. Based on UV-vis, X-ray fluorescence spectroscopy (XRF), and X-ray photoelectron spectroscopy (XPS) measurements, the cobalt catalyst appeared to be limiting the photocathode performance mainly via cobalt demetallation from the oxime ligand. This study highlights the need for a deeper understanding of the effect of catalyst molecular design on photocathode performance.
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| 5. |
- Materna, Kelly L., et al.
(författare)
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Using Surface Amide Couplings to Assemble Photocathodes for Solar Fuel Production Applications
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 12:4, s. 4501-4509
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Tidskriftsartikel (refereegranskat)abstract
- A facile surface amide-coupling method was examined to attach dye and catalyst molecules to silatrane-decorated NiO electrodes. Using this method, electrodes with a push-pull dye were assembled and characterized by photoelectrochemistry and transient absorption spectroscopy. The dye-sensitized electrodes exhibited hole injection into NiO and good photoelectrochemical stability in water, highlighting the stability of the silatrane anchoring group and the amide linkage. The amide-coupling protocol was further applied to electrodes that contain a molecular proton reduction catalyst for use in photocathode architectures. Evidence for catalyst reduction was observed during photoelectrochemical measurements and via photocathodes.
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| 6. |
- McCarthy, Brian D., et al.
(författare)
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Facile Orientational Control of M2L2P SURMOFs on < 100 > Silicon Substrates and Growth Mechanism Insights for Defective MOFs
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 11:41, s. 38294-38302
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Tidskriftsartikel (refereegranskat)abstract
- Layer-by-layer growth of Cu-2(bdc)(2)(dabco) surface-mounted metal organic frameworks (SURMOFs) was investigated on silicon wafers treated with different surface anchoring molecules. Well-oriented growth along the [100] and [001] directions could be achieved with simple protocols: growth along the [100] direction was achieved by substrate pretreatment with 80 degrees C piranha, while growth along the [001] direction was enabled by only rinsing silicon with absolute ethanol. Growth along the [001] direction produced more homogeneous SURMOF films. Optimization to enhance [001]-preferred orientation growth revealed that small changes in the SURMOF growth sequence (the number of rinse steps and linker concentrations) have a noticeable impact on the final film quality and the number of misaligned crystals. This new straightforward protocol was used to successfully grow other layer pillar-type SURMOFs, including the growth of Cu-2(bdc)(2)(bipy) with simultaneous suppression of framework interpenetration.
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