Ti K-edge x-ray absorption near edge spectroscopy (XANES) was used to explore the Ti valence and coordination in Ti-activated sodium alanate. An empirical relationship was established between the Ti valence and the Ti K-edge onset based on a set of standards. This relationship was used to estimate oxidation states of the titanium catalyst in 2 mol% and 4 mol% Ti-doped NaAlH4. These results demonstrate that the formal titanium valence is zero in doped sodium alanate and nearly invariant during hydrogen cycling. A qualitative comparison of the edge fine structure suggests that the Ti is present on the surface in the form of amorphous TiAl3.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let

Many researchers have focused in recent years on resolving the crucial problem of capacity fading in Li ion batteries when carbon anodes are replaced by other group-IV elements (Si, Ge, Sn) with much higher capacities. Some progress was achieved by using different nanostructures (mainly carbon coatings), with which the cycle numbers reached 100-200. However, obtaining longer stability via a simple process remains challenging. Here we demonstrate that a nanostructure of amorphous hierarchical porous GeO(x) whose primary particles are ~3.7 nm diameter has a very stable capacity of ~1250 mA h g(-1) for 600 cycles. Furthermore, we show that a full cell coupled with a Li(NiCoMn)(1/3)O(2) cathode exhibits high performance.

The existing Ni-yttria-stabilized zirconia anodes in solid oxide fuel cells (SOFCs) perform poorly in carbon-containing fuels because of coking and deactivation at desired operating temperatures. Here we report a new anode with nanostructured barium oxide/nickel (BaO/Ni) interfaces for low-cost SOFCs, demonstrating high power density and stability in C3H8, CO and gasified carbon fuels at 750°C. Synchrotron-based X-ray analyses and microscopy reveal that nanosized BaO islands grow on the Ni surface, creating numerous nanostructured BaO/Ni interfaces that readily adsorb water and facilitate water-mediated carbon removal reactions. Density functional theory calculations predict that the dissociated OH from H2O on BaO reacts with C on Ni near the BaO/Ni interface to produce CO and H species, which are then electrochemically oxidized at the triple-phase boundaries of the anode. This anode offers potential for ushering in a new generation of SOFCs for efficient, low-emission conversion of readily available fuels to electricity.

While pseudocapacitors represent a promising option for electrical energy storage, the performance of the existing ones must be dramatically enhanced to meet today's ever-increasing demands for many emerging applications. Here we report a nanostructured, mixed-valent manganese oxide film that exhibits anomalously high specific capacitance (∼2530 F/g of manganese oxide, measured at 0.61 A/g in a two-electrode configuration with loading of active materials ∼0.16 mg/cm(2)) while maintaining excellent power density and cycling life. The dramatic performance enhancement is attributed to its unique mixed-valence state with porous nanoarchitecture, which may facilitate rapid mass transport and enhance surface double-layer capacitance, while promoting facile redox reactions associated with charge storage by both Mn and O sites, as suggested by in situ X-ray absorption spectroscopy (XAS) and density functional theory calculations. The new charge storage mechanisms (in addition to redox reactions of cations) may offer critical insights to rational design of a new-generation energy storage devices.

We discovered that perovskite (Ba,La)SnO 3 can have excellent carrier mobility even though its band gap is large. The Hall mobility of Ba 0.98 La 0.02 SnO 3 crystals with the n-type carrier concentration of ∼8-10×10 19 cm -3 is found to be ∼103 cm 2 V -1 s -1 at room temperature, and the precise measurement of the band gap Δ of a BaSnO 3 crystal shows Δ=4.05 eV, which is significantly larger than those of other transparent conductive oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO 3 is a promising candidate for transparent conductor applications and also epitaxial all-perovskite multilayer devices. a) Author to whom correspondence should be addressed. Electronic mail: sangc@physics.rutgers.edu 2 Transparent conducting oxides (TCOs), exhibiting the contraindicative properties of optical transparency in the visible region and high DC electrical conductivity, are widely utilized as optical window electrodes in photovoltaic devices, liquid crystal displays and solar energy conversion devices. [1][2][3] There have been significant attempts to find alternative TCO materials to replace indium tin oxide due to its soaring price, and new TCOs such as doped ZnO and SnO 2 have been, in fact, already utilized. On the other hand, most of TCOs that have been investigated so far are associated with band gaps significantly less than 4 eV, so they do not transmit ultraviolet (UV) light.For example, the band gaps of SrTiO 3 (STO), ZnO, In 2 O 3 , and SnO 2 are 3.25, 3.3, 2.9, and 3.6 eV, respectively. 4-7 Thus, the discovery of TCOs with band gaps > 3.6 eV is central to enhance the efficiency of, for example, solar energy harvesting.Furthermore, the epitaxial all-perovskite multilayer heterostructures based on STO have recently attracted much attention due to the multiplicity of advantageous physical properties of perovskites. These all-perovskite multilayer heterostructures have great potentials for innovative micro-and nanoelectronic devices. 8,9 However, the mobility of doped STO is low at room temperature (RT) (~11 cm 2 V -1 s -1 ), 10 and the instability of oxygen content in doped oxides such as oxygen-deficient STO is often a detrimental issue inducing fatigue and degradation. 11 Therefore, the critical matter of the development of all-perovskite multilayer devices is finding new perovskite materials exhibiting high carrier mobility near RT and good oxygen stability.Herein, we report that La-doped perovskite BaSnO 3 (BSO) exhibits high carrier mobility with a large band gap, and thus is a promising candidate for transparent conductor applications with possible use in epitaxial all-perovskite multilayer devices.Alkaline earth stannates, with the formula of ASnO 3 (A=Ca, Sr and Ba), are widely used in the electronic industry for their optimal dielectric and gas-sensing properties. 12-14 BSO has an ideal cubic perovskite structure, and is an insulator with a valence band derived from orbitals of π-symmetry (mainly of oxygen 2p-character) and a conduction band with dominant Sn 5s-character. 15 T...