The reaction mechanism of α-MnO having 2×2 tunnel structure with zinc ions in a zinc rechargeable battery, employing an aqueous zinc sulfate electrolyte, was investigated by in situ monitoring structural changes and water chemistry alterations during the reaction. Contrary to the conventional belief that zinc ions intercalate into the tunnels of α-MnO , we reveal that they actually precipitate in the form of layered zinc hydroxide sulfate (Zn (OH) (SO )⋅5 H O) on the α-MnO surface. This precipitation occurs because unstable trivalent manganese disproportionates and is dissolved in the electrolyte during the discharge process, resulting in a gradual increase in the pH value of the electrolyte. This causes zinc hydroxide sulfate to crystallize from the electrolyte on the electrode surface. During the charge process, the pH value of the electrolyte decreases due to recombination of manganese on the cathode, leading to dissolution of zinc hydroxide sulfate back into the electrolyte. An analogous phenomenon is also observed in todorokite, a manganese dioxide polymorph with 3×3 tunnel structure that is an indication for the critical role of pH changes of the electrolyte in the reaction mechanism of this battery system.

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We report remarkably high energy conversion efficiency (4.5% at 100 mW cm(-2)) of a dye-sensitized solar cell in the solid state, using composite polymer electrolytes containing fumed silica nanoparticles.

Microbial biofouling is one of the major obstacles for reaching the ultimate goal of realizing a high permeability over a prolonged period of nanofiltration operation. In this study, the hybrid nanocomposite membranes consisting of silver (Ag) nanoparticles with antibiofouling capability on microorganism and polyamide (PA) were prepared by in situ interfacial polymerization and characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The hybrid membranes were shown to possess the dramatic antibiofouling effect on Pseudomonas. In addition, Ag nanocomposite membranes had little influence on the performances of the membrane such as on water flux and salt rejection. SEM analysis results showed that all Pseudomonas were dead on the PA/Ag nanocomposite membrane, indicating the effectiveness of silver nanoparticles. This investigation offers a strong potential for possible use as a new type of antibiofouling membrane.Pseudomonas was deposited on the pristine silver nanoparticle immobilized TFC membranes, and cultivated in the incubator at 378C and at 90 AE 5% humidity for 24 hr. Figure 1. Schematic diagram of the membrane permeation test. 566 S. Y. Lee et al.Figure 8. SEM surface images of PA/Ag membranes after antibiofouling test. (a) PA and (b) PA/Ag.

Dye-sensitized solar cells (DSSCs) are low-cost photovoltaic devices that provide a high energy conversion effi ciency of 11%. [ 1 ] High conversion effi ciency, good stability, and easy fabrication are essential for commercialization of DSSCs. [ 2 ] Although DSSCs with liquid electrolytes have been reported to exhibit high effi ciency, there has been interest in developing a solid-state DSSC (ssDSSC) due to its potential to decrease the overall weight of the cells and to provide long-term durability and fl exibility. Several methods have been developed to fabricate ssDSSCs employing quasi-solid or solid polymer electrolytes. [3][4][5][6][7][8][9][10][11] In ssDSSCs, hole transporting materials (HTMs) and the control of interfacial properties between the nanoporous TiO 2 layer and the HTM are critical to the photoconversion effi ciency of the cells. Recently, HTMs have been extensively investigated as potential replacements for conventional I 3 − /I − redox electrolyte systems using iodine (I 2 ) in DSSCs. [12][13][14][15][16][17][18] As an organic HTM, spiro-OMeTAD was used for an iodine free ssDSSC and showed higher effi ciency of 5.1%. [ 17 , 18 ] Inorganic HTMs such as CuI showed a good effi ciency of 4.7%, [ 12 ] but the crystal formation of metal oxide gradually reduced cell performance. [ 19 ] Another possibility is the utilization of p-type conducting polymers, e.g., polypyrrole, polyaniline, polydiacetylene, poly (3-octylthiopehene), and poly(3,4-ethylenedioxythiophene) (PEDOT). [20][21][22][23][24][25][26] These polymers are advantageous over other small molecules due to their low cost, good stability, simple fabrication using spin-coating, and easy preparation of designable structures. Recently, Ho et al. reported an iodine (I 2 )-free ssDSSC using polyaniline/carbon black composite with imidazolium iodide derivatives, which effectively generates I − / I 3 − redox couples without addition of iodine (I 2 ). [ 27 ] However, while conductive polymers offer many advantages, they show low energy conversion effi ciencies due to poor penetration into the nanopores of TiO 2 photoelectrodes that arises from mismatches between the molecular sizes of the polymers and the pore sizes of the TiO 2 layer. Recently, Yanagida et al. were successful at improving the power conversion effi ciency signifi cantly up to 2.85%, which was the highest effi ciency for an iodine-free ssDSSC using a conductive polymer as HTM. [28][29][30] The penetration of a conductive polymer into TiO 2 porous layers was successfully improved via the in situ photoelectrochemical polymerization of a heterocyclic monomer, e.g., 2,2'-bis(3,4-ethylenedioxythiophene) (bis-EDOT). [ 29 ] However, the maximum penetration depth of the conductive polymer into the TiO 2 layer was 4-5 μ m, above which cell effi ciency was decreased, resulting from insuffi cient interfacial properties of electrode/HTM despite increased dye adsorption. More recently, Liu et al. further improved cell efficiency up to 6.1% using indoline D149 dye as a sensitizer, [ 31 ] whe...