We report a new solution deposition method to synthesize an unprecedented type of two-dimensional ordered mesoporous carbon nanosheets via a controlled low-concentration monomicelle close-packing assembly approach. These obtained carbon nanosheets possess only one layer of ordered mesopores on the surface of a substrate, typically the inner walls of anodic aluminum oxide pore channels, and can be further converted into mesoporous graphene nanosheets by carbonization. The atomically flat graphene layers with mesopores provide high surface area for lithium ion adsorption and intercalation, while the ordered mesopores perpendicular to the graphene layer enable efficient ion transport as well as volume expansion flexibility, thus representing a unique orthogonal architecture for excellent lithium ion storage capacity and cycling performance. Lithium ion battery anodes made of the mesoporous graphene nanosheets have exhibited an excellent reversible capacity of 1040 mAh/g at 100 mA/g, and they can retain at 833 mAh/g even after numerous cycles at varied current densities. Even at a large current density of 5 A/g, the reversible capacity is retained around 255 mAh/g, larger than for most other porous carbon-based anodes previously reported, suggesting a remarkably promising candidate for energy storage.

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We demonstrate for the first time the controlled Sn-doping in TiO(2) nanowire (NW) arrays for photoelectrochemical (PEC) water splitting. Because of the low lattice mismatch between SnO(2) and TiO(2), Sn dopants are incorporated into TiO(2) NWs by a one-pot hydrothermal synthesis with different ratios of SnCl(4) and tetrabutyl titanate, and a high acidity of the reactant solution is critical to control the SnCl(4) hydrolysis rate. The obtained Sn-doped TiO(2) (Sn/TiO(2)) NWs are single crystalline with a rutile structure, and the incorporation of Sn in TiO(2) NWs is well controlled at a low level, that is, 1-2% of Sn/Ti ratio, to avoid phase separation or interface scattering. PEC measurement on Sn/TiO(2) NW photoanodes with different Sn doping ratios shows that the photocurrent increases first with increased Sn doping level to >2.0 mA/cm(2) at 0 V vs Ag/AgCl under 100 mW/cm(2) simulated sunlight illumination up to ~100% enhancement compared to our best pristine TiO(2) NW photoanodes and then decreases at higher Sn doping levels. Subsequent annealing of Sn/TiO(2) NWs in H(2) further improves their photoactivity with an optimized photoconversion efficiency of ~1.2%. The incident-photon-to-current conversion efficiency shows that the photocurrent increase is mainly ascribed to the enhancement of photoactivity in the UV region, and the electrochemical impedance measurement reveals that the density of n-type charge carriers can be significantly increased by the Sn doping. These Sn/TiO(2) NW photoanodes are highly stable in PEC conversion and thus can serve as a potential candidate for pure TiO(2) materials in a variety of solar energy driven applications.

We developed a postgrowth doping method of TiO2 nanowire arrays by a simultaneous hydrothermal etching and doping in a weakly alkaline condition. The obtained tungsten-doped TiO2 core-shell nanowires have an amorphous shell with a rough surface, in which W species are incorporated into the amorphous TiO2 shell during this simultaneous etching/regrowth step for the optimization of photoelectrochemical performance. Photoanodes made of these W-doped TiO2 core-shell nanowires show a much enhanced photocurrent density of ~1.53 mA/cm(2) at 0.23 V vs Ag/AgCl (1.23 V vs reversible hydrogen electrode), almost 225% of that of the pristine TiO2 nanowire photoanodes. The electrochemical impedance spectroscopy measurement and the density functional theory calculation demonstrate that the substantially improved performance of the dual W-doped and etched TiO2 nanowires is attributed to the enhancement of charge transfer and the increase of charge carrier density, resulting from the combination effect of etching and W-doping. This unconventional, simultaneous etching and doping of pregrown nanowires is facile and takes place under moderate conditions, and it may be extended for other dopants and host materials with increased photoelectrochemical performances.

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Mesoporous thin films with various compositions are unique architectures for photoelectrochemical (PEC) solar cells. In this paper, we report the synthesis of highly ordered, multi-layered, continuous mesoporous TiO 2 thin films with uniform large pores, crystalline walls and tunable film thickness, via a ligand-assisted evaporation induced self assembly (EISA) method. A Ti(acetylacetone) precursor and a diblock copolymer PEO-b-PS are employed for the controlled assembly of the TiO 2 /template mesostructure, followed by a two-step pyrolysis that generates carbon residue as an intermediate protection layer to support the TiO 2 framework and mesostructures during the crystallization. Other transition metal ion dopants (such as Cr, Ni and Co) can be facilely incorporated into the TiO 2 frameworks by co-assembly of these metal acetylacetone precursors during the EISA process. The obtained TiO 2 thin film possesses an ordered monoclinic mesostructure distorted from a (110)-oriented primitive cubic structure, uniform and tunable large pores of 10-30 nm, a large surface area of $100 m 2 g À1 and a high crystallinity anatase wall. The film thickness can be well controlled from 150 nm to several microns to tune the absorption, with the capability of generating free-standing film morphologies. Furthermore, this designed architecture allows for effective post-deposition of other small-bandgap semiconductor nanomaterials inside the large, open and interconnecting mesopores, leading to significantly improved solar absorption and photoconversion. As a proof-of-concept, we demonstrate that the photoanodes made of 4.75 mm thick mesoporous TiO 2 film with deposited cadmium sulfide quantum dots exhibit excellent performance in PEC water splitting, with an optimized photocurrent density of 6.03 mA cm À2 and a photoconversion efficiency of 3.9%. These multi-layered mesoporous TiO 2 -based thin films can serve as a unique architecture for PEC and other solar energy conversion and utilization.

Inorganic chemistry Z 0100 Surface Modifications of Electrode Materials for Lithium Ion Batteries -[131 refs.]. -(FU, L. J.; LIU, H.; LI, C.; WU, Y. P.; RAHM, E.; HOLZE*, R.; WU, H. Q.; Solid State Sci. 8 (2006) 2, 113-128; Inst. Chem., TU Chemnitz, D-09107 Chemnitz, Germany; Eng.) -Schramke 17-232