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The growing demand for efficient energy storage systems, particularly in portable electronics and electric vehicles, has led to increased interest in supercapacitors, which offer high power density, rapid charge/discharge rates, and long cycle life. However, improving their energy density without compromising performance remains a challenge. In this study, we developed novel 3D-printed reduced graphene oxide (rGO) electrodes coated with polyaniline (PANI) to enhance their electrochemical properties. The rGO 3D-printed electrodes were fabricated using direct ink writing (DIW), which allowed precise control over thickness, ranging from 4 to 24 layers. A unique ink formulation was optimized for the printing process, consisting of rGO, cellulose acetate (CA) as a binder, and acetone as a solvent. The PANI coating was applied via chemical oxidative polymerization (COP) with up to five deposition cycles. Electrochemical testing, including cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS), revealed that 12-layer electrodes with three PANI deposition cycles achieved the highest areal capacitance of 84.32 mF/cm2. While thicker electrodes (16 layers and beyond) experienced diminished performance due to ion diffusion limitations, the composite electrodes demonstrated excellent cycling stability, retaining over 80% of their initial capacitance after 1500 cycles. This work demonstrates the potential of 3D-printed PANI/rGO electrodes for scalable, high-performance supercapacitors with customizable architectures. [ABSTRACT FROM AUTHOR]

Electrospinning is known mainly for polymers. We show that this simple technique allows to shape molecules that are useful for organic photovoltaic cells into wires, a morphology that is otherwise not generally obtained. A special advantage of our method is the simple mixing approach that allows to test blends of promising compounds, without the need for chemical pretreatment, modification or immobilization. Our materials are TPP-NH2 (monoamino-tetraphenylporphyrine) and FF-TPP (diphenylalanine-TPP), both candidates for electron donors in solar cells. We found that a mixture of FF-TPP with FF (diphenylalanine) is especially advantageous for forming quasi infinitely long wires of 100 to 1000 nm diameter. We analyzed the wire morphology with optical, electron, and scanning force microscopy, and we used X-ray diffraction and infrared spectroscopy to elucidate the internal structure. The wire is composed of intact molecules, but shows surprisingly low crystallinity, in stark contrast to the single components. [ABSTRACT FROM AUTHOR]

We report the development and characterization of a detection technique for scattering-type scanning near-field optical microscopy (s-SNOM) that enables near-field amplitude and phase imaging at two or more wavelengths simultaneously. To this end, we introduce multispectral pseudoheterodyne (PSH) interferometry, where infrared lasers are combined to form a beam with a discrete spectrum of laser lines and a time-multiplexing scheme is employed to allow for the use of a single infrared detector. We first describe and validate the implementation of multispectral PSH into a commercial s-SNOM instrument. We then demonstrate its application for the real-time correction of the negative phase contrast (NPC), which provides reliable imaging of weak IR absorption at the nanoscale. We anticipate that multispectral PSH could improve data throughput, reduce effects of sample and interferometer drift, and help to establish multicolor s-SNOM imaging as a regular imaging modality, which could be particularly interesting as new infrared light sources become available.