Browsing by Author "Krueger, Anke"

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Open Access
Controlled formation of porous 2D lattices from C3‐symmetric Ph6-Me‐tribenzotriquinacene‐OAc3
(2023) Toksabay, Sinem; Leisegang, Markus; Christ, Andreas; Härtl, Patrick; Krebs, Johannes; Marder, Todd B.; Haldar, Soumyajyoti; Heinze, Stefan; Bode, Matthias; Krueger, Anke
The on‐surface self‐assembly of molecules to form holey nanographenes is a promising approach to control the properties of the resulting 2D lattice. Usually, planar molecules are utilized to prepare flat, structurally confined molecular layers, with only a few recent examples of warped precursors. However, control of the superstructures is limited thus far. Herein, we report the temperature‐controlled self‐assembly of a bowl‐shaped, acetylated C3‐symmetric hexaphenyltribenzotriquinacene derivative on Cu(111). Combining scanning tunneling microscopy (STM) and density functional theory (DFT) confirms the formation of highly differing arrangements starting with π‐stacked bowl‐to‐bowl dimers at low coverage at room temperature via chiral honeycomb structures, an intermediate trigonal superstructure, followed by a fully carbon‐based, flattened hexagonal superstructure formed by on‐surface deacetylation, which is proposed as a precursor for holey graphene networks with unique defect structures.
Open Access
In situ polymerization of EDOT onto sulfonated onion-like carbon for efficient pseudocapacitor electrodes
(2024) Bauer, Christian; Kirchner, Maximilian; Krueger, Anke
Conductive polymers (CPs) and carbon nanoparticles are attractive active materials for binder free supercapacitor electrodes. A composite of these components combines high pseudocapacitance of CPs with the mechanical stability of carbon particles. Homogeneous percolation of both materials in the composite is fundamental for electrochemical performance but is typically hindered due to insoluble starting materials. Here, we propose a template assisted polymerization of 3,4-ethylenedioxythiophene (EDOT) onto sulfophenylated onion-like carbon ( SPOLC ). Besides providing dispersibility for the carbon particles, anionic functionalization also promotes the mechanical and electrical connection between PEDOT and SPOLC . The resulting composite precipitates as a viscoelastic aqueous slurry enabling direct processing to binder-free supercapacitor electrodes. The synergistic combination of mechanical and electrochemical properties in the composite leads to a specific capacitance of 77 F g -1 and a capacitance retention above 90% after 70 000 cycles. Our findings highlight how the functionalization of carbon enhances dispersibility in water and provides connectivity with the CP, thereby boosting the performance and stability in supercapacitor applications.
Open Access
Scalable fabrication of flexible supercapacitor electrodes using sustainable water‐based onion‐like carbon inks
(2024) Bauer, Christian; Neff, Tobias; Day, Adam; Krueger, Anke
The increasing usage of electrical energy storage solutions demands for cost effective, scalable and sustainable manufacturing technologies. Deposition of functional inks, carrying electrochemically active materials is a suitable technique as it delivers material with selected properties only to required locations. However, the production of stable dispersions featuring high concentrations of active material ‐ necessary for effective deposition ‐ is challenging. Here we present an approach to print supercapacitor electrodes with onion‐like carbon as active material, using a simple, cost‐effective process as well as a water‐based ink. The ink is highly stable and can be deposited by spray and inkjet techniques. The fabricated electrodes offer a capacitance of up to 14 mF cm -2 (27 F g -1 ) and retained 97 % of their initial capacitance after 5000 cycles, demonstrating excellent performance and stability of the coating.