| 1. |
- Apaydin, Dogukan H., et al.
(author)
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Electrochemical Capture and Release of CO2 in Aqueous Electrolytes Using an Organic Semiconductor Electrode
- 2017
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In: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 9:15, s. 12919-12923
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Journal article (peer-reviewed)abstract
- Developing efficient methods for capture and controlled release of carbon dioxide is crucial to any carbon. capture and utilization technology. Herein we present an approach using an organic. semiconductor electrode to electrochemically capture dissolved CO2 in aqueous electrolytes. The process relies on electrochemical reduction of a thin film of a naphthalene bisimide derivative, 2,7,bis (4-(2- (2-ethylhexyl)thiazol-4-yl)phenyObenzo [lmn][3,8] phenanthroline-1,3,6,8(2H,7H)-tetraone (NBIT). This molecule is specifically tailored to afford one-electron reversible and one-electron quasi-reversible reduction in aqueous conditions while, not dissolving or degrading. The reduced NBIT reacts with CO2 to form a stable aemicarbonate salt, which can be subsequently oxidized electrochemically to release CO2. The semicarbonate structure is confirmed by in situ IR spectroelectrochemistry. This process of capturing and releasing carbon dioxide can be realized in an oxygen-free environment under ambient pressure and temperature, with uptake efficiency for CO2 capture of similar to 2.3 mmol g(-1). This is on par with the best solution-phase amine chemical capture technologies available today.
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| 2. |
- Schubert, Jasmin S., et al.
(author)
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Nature of the Active Ni State for Photocatalytic Hydrogen Generation
- 2023
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In: Advanced Materials Interfaces. - : WILEY. - 2196-7350.
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Journal article (peer-reviewed)abstract
- Thermal treatments can have detrimental effects on the photocatalytic hydrogen (H2) evolution performance and impact the formation mechanism of the active state of surface-supported co-catalysts. In this work, a range of Ni-based co-catalysts is investigated immobilized on TiO2, evaluated their H2 evolution rates in situ over 21 h, and analyzed the samples at various stages with a comprehensive set of spectroscopic and microscopy techniques. It is found that achieving the optimal hydrogen evolution (HER) performance requires the right Ni0:Ni2+ ratio, rather than only Ni0, and that Ni needs to be weakly adsorbed on the TiO2 surface to create a dynamic state. Under these conditions, Ni can undergo an efficient redox shuttle, involving the transformation of Ni2+ to Ni0 and back after releasing the accumulated electrons for H+ reduction (i.e., Ni2+ <-> Ni0). Yet, when the calcination temperature of the Ni/TiO2 photocatalysts increases, resulting in stronger coordination/adsorption of Ni on TiO2, this process is gradually inhibited, which ultimately leads to decreased HER performances. This work emphasizes the significance and influence of thermal treatments on the Ni active state formation - a process that can be relevant to other HER co-catalysts. This research underscores the impact of thermal treatment on the formation of Nis active state for hydrogen evolution reaction (HER) . For optimal performance, Ni should weakly adsorb onto the substrate, efficiently shuttling between Ni2+ and Ni0 and reversing after H+ reduction (Ni2+ <-> Ni0). However, raising the calcination temperature strengthens Ni coordination/adsorption on the substrate, gradually inhibiting this process and reducing HER performances.image
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