Rechargeable Na/NaFePO 4 cells with a sodium bis(trifluoromethanesulfonyl)imide (NaTFSI)-incorporated butylmethylpyrrolidinium (BMP)-TFSI ionic liquid (IL) electrolyte are demonstrated with an operation voltage of $3 V. High-performance NaFePO 4 cathode powder with an olivine crystal structure is prepared by chemical delithiation of LiFePO 4 powder followed by electrochemical sodiation of FePO 4 . This IL electrolyte shows high thermal stability (>400 C) and non-flammability, and is thus ideal for high-safety applications. The effects of NaTFSI concentration (0.1-1.0 M) on cell performance at 25 C and 50 C are studied. At 50 C, an optimal capacity of 125 mA h g À1 (at 0.05 C) is found for NaFePO 4 in a 0.5 M NaTFSI-incorporated IL electrolyte; moreover, 65% of this capacity can be retained when the charge-discharge rate increases to 1 C. This ratio (reflecting the rate capability) is higher than that found in a traditional organic electrolyte. With a 1 M NaTFSI-incorporated IL electrolyte, a 13% cell capacity loss after 100 charge-discharge cycles is measured at 50 C, compared to the 38% observed in an organic electrolyte under the same conditions.

Doping is an effective way to tune the band gap of metal oxide semiconductor materials. Doped tin oxide nanoparticles have proven to be effective materials for various electro-optical applications, particularly when deposited in thin-film architectures. However, doping in metal oxide nanoparticles generally leads to distorted shapes and a lack of uniformity, making the ready preparation of spherical, monodisperse doped tin oxide stand-alone nanoparticles an elusive task. This report describes a facile, solution-based method for the synthesis of stable, monodisperse antimony- and zinc-doped tin oxide nanoparticles, which opens the door to disperse these materials in a variety of media and expand their range of applications. The band gap of the tin oxide nanoparticles was successfully tuned upon doping with antimony and zinc. The tin-oxide-based nanomaterials were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Separately, the optical properties of the nanoparticles were evaluated by UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). These nanoparticles can be very effective in creating well-controlled systems for photocatalysis, solar cells, optoelectronics, multilayered devices, and for the treatment of air and water pollutants.

Gold-silver nanoshells (GS-NSs) having a tunable surface plasmon resonance (SPR) were employed to facilitate charge separation of photoexcited carriers in the photocalytic production of hydrogen from water. Zinc indium sulfide (ZnIn2S4; ZIS), a visible-light-active photocatalyst, where the band gap varies with the [Zn]/[In] ratio, was used as a model ZIS system (E(g) = 2.25 eV) to investigate the mechanisms of plasmonic enhancement associated with the nanoshells. Three types of GS-NS cores with intense absorptions centered roughly at 500, 700, and 900 nm were used as seeds for preparing GS-NS@ZIS core-shell structures via a microwave-assisted hydrothermal reaction, yielding core-shell particles with composite diameters of ∼200 nm. Notably, an interlayer of dielectric silica (SiO2) between the GS-NSs and the ZIS photocatalyst provided another parameter to enhance the production of hydrogen and to distinguish the charge-transfer mechanisms. In particular, the direct transfer of hot electrons from the GS-NSs to the ZIS photocatalyst was blocked by this layer. Of the 10 particle samples examined in this study, the greatest hydrogen gas evolution rate was observed for GS-NSs having a SiO2 interlayer thickness of ∼17 nm and an SPR absorption centered at ∼700 nm, yielding a rate 2.6 times higher than that of the ZIS without GS-NSs. The apparent quantum efficiencies for these core-shell particles were recorded and compared to the absorption spectra. Analyses of the charge-transfer mechanisms were evaluated and are discussed based on the experimental findings.

Self-assembled monolayers (SAMs) were prepared by the adsorption of aliphatic dithiocarboxylic acids (ADTCAs) onto the surface of gold. The films were characterized using a variety of analytical techniques:  ellipsometry, contact angle goniometry, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). These studies found that the ADTCAs attach to the surface of gold via equivalent binding of both sulfur moieties in the dithiocarboxylic acid headgroup. The stability of these highly orientated SAMs was examined at room temperature under a variety of atmospheric conditions (i.e., under argon, oxygen, air, and humid air) and compared to the stability of related SAMs derived from n-alkanethiols. The ADTCA-based SAMs were observed to decompose relatively rapidly via oxidation of the sulfur headgroups, as judged by XPS. The rate of desorption of the SAMs was observed to vary as a function of the atmospheric conditions as well as the chain length of the ADTCA adsorbates.

Thin films of the silver indium sulfide (AgIn 5 S 8 ) ternary semiconductor were prepared from acidic aqueous solutions containing silver nitrate, indium nitrate, and thioacetamide. Various preparative parameters, such as pH of the precursor solution, silver to indium concentration ratio [Ag]/[In], and postreaction thermal treatment conditions were changed in order to grow uniform and adherent thin films on glass substrates. A series of X-ray diffraction patterns and scanning electron micrographs were used to reveal the growth process over time. It was found that granular Ag 2 S primary films were first attached to the glass substrate, followed by the indium sulfide deposition. A (1 1 1) preferred oriented AgIn 5 S 8 with cubic spinel structure was obtained from the [Ag]/[In] ) 4 and pH 0.6 precursor solution after 673 K thermal treatment for 1 h in an Ar environment. A two-step deposition mechanism was proposed and discussed in terms of stability constants of metal complexes and classical nucleation theory. In addition, our preliminary study showed that 3-mercaptopropyl-trimethoxysilane (MPS)-modified glass substrates further promoted the homogeneity and adhesion of AgIn 5 S 8 thin films.