Zeitschriftenaufsätze und Buchbeiträge

Transition metal dichalcogenide (TMD) nanoparticles have attracted much attention recently for lithium and sodium ion batteries (LIBs and SIBs) due to their layered structures, which act as host lattices when reacting with ions to yield intercalation compounds. In the present article, WS2 nanoparticles are modified through hydrogen plasma treatment, and the hydrogenated WS2 (H-WS2) nanoparticles demonstrate clearly enhanced electrochemical performance as an anode material for LIBs and SIBs. H-WS2 nanoparticles are fabricated via hydrogen plasma treatment at 300 ˚C for 2 hours. A transmission electron microscopy (TEM) investigation shows that the nanoparticles have a disordered surface layer with a thickness of around 2.5 nm after the treatment, and this is confirmed by the results of Raman spectroscopy. A shift in the X-ray photoelectron spectroscopy (XPS) peaks indicates that the structural surface disorders are incorporated in the crystalline structure. The H-WS2 based LIBs and SIBs possess significantly higher specific capacities at different current densities. In addition, electrochemical impedance spectroscopy (EIS) reveals a drastic decrease in the charge-transfer resistance for both the LIBs and SIBs, which implies that the plasma hydrogenated electrode is more favorable for electron transportation during the electrochemical process. The improved rate performance of H-WS2 when applied to both LIBs and SIBs can be attributed to the reduced charge-transfer resistivity at the disordered surface layer and the improved electronic conductivity due to the disordered surface in the crystalline structure.

A photolithographic technique based on dry film photoresists for facile and low-cost patterning of microcantilever beams is presented. Dry film photoresists enable instantly homogenous photoresist coatings on flexible and 3D patterned substrate surfaces, represented here by microcantilever beams, which is otherwise challenging if conventional spin-coating of photoresist is utilized. Compared to alternative microtechnologies, such as focused ion beam milling or resist spray coating, our strategy is far less elaborate, fully compatible with routine additive and subtractive microfabrication processes and can be readily scaled. We show specifically microcantilever shape modification by CF4 reactive ion etching, localized metal deposition in combination with conventional lift-off procedures as well as a utilization of patterned dry film photoresists as permanent microstructural elements. These microstructural elements are in particular flat-ended cylindrical dry resist micropillars created at the freestanding end of the cantilever beam that can be employed as scanning probes. The resist pillars enabled imaging of a 3T3 mouse fibroblast cell culture surface to determine their elastic force constants. Alongside UV-exposure by a conventional mask aligner, we also demonstrate dry film photoresist exposure by contact-free laser lithography eliminating possible substrate damage by photomask contact.