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The First-Row Transition Metal-Based Electrocatalysts for Water Splitting and Biomass UpgradingLiu, Xuan January 2020 (has links)
No description available.
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Inorganic Electrocatalysts for Innovative Water Splitting and Organic UpgradingJiang, Nan 01 December 2018 (has links)
The booming worldwide demand for energy and the increasing concerns about global warming due to fossil fuel consumption have urged the development of techniques for storing and converting renewable and clean energy resources. Electrocatlytic or photoelectrocatalytic water splitting to generate green energy carrier H2 with sustainable energy input, like solar, has been regarded as an attractive strategy for carbon-neutral energy needs. However, the sluggish kinetics for both half reactions (HER and OER), high overpotentials and thermodynamic requirements, and H2 and O2 gas crossover have been regarded as the major challenges, which limit its widespread application.
On account of high efficiency and fast reaction rate, proton exchange membrane electrolyzer (PEME) has been developed as a mature technology for water splitting under acidic conditions. Nonetheless, it requires noble metals as robust and competent catalysts (like Pt for HER and IrO2 for OER), which is economically unfavorable. Owing to the thermodynamic convenience for OER and the integration of HER and OER in the same electrolyte, anion exchange membrane electrolyzer (AEME) has also been explored under alkaline conditions, utilizing first-row transition metals as bifunctional catalysts. However, for both PEME and AEME, H2 and O2 are generated simultaneously. Even though “gas impermeable” membranes are employed, the formation of H2/O2 mixture is inevitable. So one part of my research introduced a new strategy to couple HER with more thermodynamically favorable biomass-derived upgrading in alkaline solution, which requires lower energy input than overall water splitting and produces more valuable and non-gas products. However, the solubility of biomass-derived organic compounds as well as the competing reaction of water oxidation limits the catalytic current density.
Therefore, we further introduce the concept of redox mediator (RM) to divide conventional water splitting into two separate steps. This allows H2 and O2 to be produced at different times as well as in different spaces and reduces the energy input required to conduct a productive step. This strategy not only prevents H2/O2 mixing but also reduces the voltage input as the redox potential of RM+/0 will be within the HER and OER thermodynamic potentials, hence allowing water splitting to be driven by photovoltaic cells with small photovoltage.
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Visible and Near Infrared Light Driven Organic Transformations via Semiconductors and Molecular PhotosensitizersHan, Guanqun January 2021 (has links)
No description available.
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Novel Polymer–Silica Composite-Based Bifunctional Catalysts for Hydrodeoxygenation of 4-(2-Furyl)-3-Buten-2-One as Model Substance for Furfural–Acetone Aldol Condensation ProductsGoepel, Michael, Ramos, Ruben, Gläser, Roger, Kubiˇcka, David 06 April 2023 (has links)
Novel bifunctional metal-loaded polymer–silica composite (PSC) catalysts were investigated
in the hydrodeoxygenation (HDO) of 4-(2-furyl)-3-buten-2-one (FAc) as a model substance for
furfural–acetone aldol condensation products. PSC catalysts were synthesized via a sol–gel method
with different polymer contents and subsequently doped with different noble metals. The product
composition of the HDO of FAc could be tuned by using catalysts with different polymer (i.e., acidic
properties) and metal content (i.e., redox properties), showing the great potential of metal-loaded PSC
materials as tunable catalysts in biomass conversions with complex reaction networks. Furthermore,
high yields (>90%) of the fully hydrodeoxygenated product (n-octane) could be obtained using noble
metal-loaded PSC catalysts in only 8 h of reaction time.
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