Formation and reduction of anodic film on polycrystalline Bi electrode in pure methanol solutions

The processes of film formation and reduction of bismuth in pure methanol are phenomenologically studied by means of cyclic voltammetry, ac voltammetry and electrochemical impedance spectroscopy methods. Film formation takes place under low electrode potentials within the potential range from -0.1 to about 0.2 V vs. Ag|AgCl resulting in the development of Bi(CH3O)ads layer. The scan rate effect on the anodic current profile is interpreted in terms of a gradual variation of uncompensated resistance, accompanying the processes of film formation and reduction. Phase sensitive ac voltammetry measurements suggest leaky insulating character of a thin anodic film in agreement with the results of electrochemical impedance experiments

All-solid Nafion®-based amperometric sensors for monitoring gaseous oxygen

Oxygen reduction has been studied at three different designs of Au/Nafion®-based all-solid amperometric sensors. These consisted of a planar-type sensor (PTS) with all electrodes sputtered on the same face of the Nafion® membrane, a capillary planar type sensor (CPTS) with the introduction of a cover bearing a capillary, and a sandwich-type sensor (STS) with the working and counter electrode layers deposited on different sides of the polymer electrolyte membrane. The response of all sensors depended heavily on humidity and the degree of Nafion® hydration but, unlike the CPTS and STS configurations, no signs of a limiting current were recorded during voltammetric experiments at an open PTS device, indicating the absence of a significant diffusion barrier in that case. All three simple and inexpensive polymerbased sensors compared well with a commercial fuel cell-type sensor, regarding their response to gaseous oxygen concentration changes

Anion Intercalation into Graphite Drives Surface Wetting

The unique layered structure of graphite with its tunable interlayer distance establishes almost ideal conditions for the accommodation of ions into its structure. The smooth and chemically inert nature of the graphite surface also means that it is an ideal substrate for electrowetting. Here, we combine these two unique properties of this material by demonstrating the significant effect of anion intercalation on the electrowetting response of graphitic surfaces in contact with concentrated aqueous and organic electrolytes as well as ionic liquids. The structural changes during intercalation/deintercalation were probed using in situ Raman spectroscopy, and the results were used to provide insights into the influence of intercalation staging on the rate and reversibility of electrowetting. We show, by tuning the size of the intercalant and the stage of intercalation, that a fully reversible electrowetting response can be attained. The approach is extended to the development of biphasic (oil/water) systems that exhibit a fully reproducible electrowetting response with a near-zero voltage threshold and unprecedented contact angle variations of more than 120° within a potential window of less than 2 V

Nanocubes of Mo6S8 Chevrel Phase as Active Electrode Material for Aqueous Lithium-Ion Batteries

The development of intrinsically safe and environmentally sustainable energy storage devices is a significant challenge. Recent advances in aqueous rechargeable lithium-ion batteries (ARLIBs) have made considerable steps in this direction. In parallel to the ongoing progress in the design of aqueous electrolytes that expand the electrochemically stable potential window, the design of negative electrode materials exhibiting large capacity and low intercalation potential attracts great research interest. Herein, we report the synthesis of high purity nanoscale Chevrel Phase (CP) Mo 6S 8via a simple, efficient and controllable molecular precursor approach with significantly decreased energy consumption compared to the conventional approaches. Physical characterization of the obtained product confirms the successful formation of CP-Mo 6S 8 and reveals that it is crystalline nanostructured in nature. Due to their unique structural characteristics, the Mo 6S 8 nanocubes exhibit fast kinetics in a 21 m lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte as a result of the shorter Li + ion diffusion distance. Full battery cells comprised of Mo 6S 8 and LiMn 2O 4 as negative and positive electrode materials, respectively, operate at 2.23 V delivering a high energy density of 85 W h kg −1 (calculated on the total mass of active materials) under 0.2 C-rate. At 4 C, the coulombic efficiency (CE) is determined to be 99% increasing to near 100% at certain cycles. Post-mortem physical characterization demonstrates that the Mo 6S 8 anode maintained its crystallinity, thereby exhibiting outstanding cycling stability. The cell outperforms the commonly used vanadium-based (VO 2 (B), V 2O 5) or (NASICON)-type LiTi 2(PO 4) 3 anodes, highlighting the promising character of the nanoscale CP-Mo 6S 8 as a highly efficient anode material. In summary, the proposed synthetic strategy is expected to stimulate novel research towards the widespread application of CP-based materials in various aqueous and non-aqueous energy storage systems.</p