A nitrogen-doped graphene/sulfur composite was further modified with atomic layers of TiO2and used as the cathode of lithium–sulfur batteries, exhibiting superior cycling stability, good rate capability and high coulombic efficiency.

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Based on ab initio calculations of both the ABC- and AB-stacked graphites, interlayer potentials (i.e., graphene-graphene interaction) are obtained as a function of the interlayer spacing using a modified Möbius inversion method, and are used to calculate basic physical properties of graphite. Excellent consistency is observed between the calculated and experimental phonon dispersions of AB-stacked graphite, showing the validity of the interlayer potentials. More importantly, layer-related properties for nonideal structures (e.g., the exfoliation energy, cleave energy, stacking fault energy, surface energy, etc.) can be easily predicted from the interlayer potentials, which promise to be extremely efficient and helpful in studying van der Waals structures.

The atomic-level tunability that results from alloying multiple transition metals with d electrons in concentrated solid solution alloys (CSAs), including high-entropy alloys (HEAs), has produced remarkable properties for advanced energy applications, in particular, damage resistance in high-radiation environments. The key to understanding CSAs' radiation performance is quantitatively characterizing their complex local physical and chemical environments. In this study, the local structure of a FeCoNiCrPd HEA is quantitatively analyzed with X-ray total scattering and extended X-ray absorption fine

A black Ti 3+ -doped single-crystal TiO 2 (Ti 3+ /TiO 2 ) was one-pot synthesized by treating metal Ti in an ionic liquid containing LiAc and HAc under mild ionothermal conditions. The ionic liquid(1-methyl-imidazolium tetrafluoroborate) supplied an environment enriched with fluoride ions for dissolving titanium foil at ionothermal condition, followed by reducing protons in acetic acid to form Ti 3+ ions, leading to Ti 3+ -doped single-crystal TiO 2 in black powder. EPR and XPS results indicated the high-concentrations of both Ti 3+ -dopants and oxygen vacancies. The Ti 3+ incorporated into TiO 2 lattice could narrow the energy band gap of TiO 2 via forming intermediate energy levels, leading to the visible photocatalyst. Meanwhile, the oxygen vacancies could inhibit the photoelectron-hole recombination. As expected, such a black Ti 3+ /TiO 2 exhibited high activity in photocatalytic degradation of organic pollutants and water splitting for H 2 production under irradiation with visible lights and/or simulated solar lights.

IntroductionAs the most popular energy storage devices, lithium-ion batteries (LIBs) enjoy the merits of relatively high energy densities, good reliability, and stability. However, LIBs are still expensive and nearing their ceiling performance. Currently, lithiumsulfur (Li-S) battery has spurred a great deal of attention and hold potential to serve as next-generation energy storage system due to its unique characteristics. Based on the complete reduction of elemental S to Li 2 S, the Li-S battery has a high theoretical energy density of 2600 W h kg −1 , 3-5 times higher than those conventional Li-ion battery cathode materials, such as layered LiCoO 2 and olivine LiFePO 4 . [1,2] Furthermore, sulfur as abundant, economical, and environment-friendly, are all in line with current public transportation and health priorities. The past years have also witnessed unprecedented improvements made by the research groups worldwide. [2][3][4][5][6][7] However, its practical application is still hinged on several tough challenges, such as the inherent poor electronic conductivity of sulfur and its insoluble discharging products (i.e., Li 2 S/Li 2 S 2 ), large volume variation (over 80%) due to the density difference between sulfur and Li 2 S/Li 2 S 2 . More importantly, the shuttle phenomenon caused by the dissolution and migration of long-chain polysulfides (Li 2 S n , 4 ≤ n ≤ 8) lead to the fast capacity decay, self-discharge, and low coulombic efficiency, which further exacerbate the serious problem.In order to address these problems, various hierarchical structured carbonaceous materials, such as porous carbons, [8,9] carbon nanotubes (CNTs), [10,11] and graphene, [12,13] have been thoroughly explored to host sulfur and confine lithium polysulfides (LiPSs). Moreover, they could offer intrinsic high conductivity for charge transport and cushion volume expansion. However, the interactions between the nonpolar hydrophobic carbonaceous materials and polar hydrophilic LiPSs are weak, [14] leading to the out-diffusion, thus deteriorating the battery performance. Electrode modification, such as the addition Freestanding cathode materials with sandwich-structured characteristic are synthesized for high-performance lithium-sulfur battery. Sulfur is impregnated in nitrogen-doped graphene and constructed as primary active material, which is further welded in the carbon nanotube/nanofibrillated cellulose (CNT/NFC) framework. Interconnected CNT/NFC layers on both sides of active layer are uniquely synthesized to entrap polysulfide species and supply efficient electron transport. The 3D composite network creates a hierarchical architecture with outstanding electrical and mechanical properties. Synergistic effects generated from physical and chemical interaction could effectively alleviate the dissolution and shuttling of the polysulfide ions. Theoretical calculations reveal the hydroxyl functionization exhibits a strong chemical binding with the discharge product (i.e., Li 2 S). Electrochemical measurements suggest that the rationally d...

Pt-doped mesoporous Ti self-doped TiO (Pt-Ti/TiO) is in situ synthesized via an ionothermal route, by treating metallic Ti in an ionic liquid containing LiOAc, HOAc, and a HPtCl aqueous solution under mild ionothermal conditions. Such Ti-enriched environment, as well as oxygen vacancies, is proven to be effective for allowing the in situ reduction of Pt ions uniformly located in the framework of the TiO bulk. The photocatalytic H evolution of Pt-Ti/TiO is significantly higher than that of the photoreduced Pt loaded on the original TiO and commercial P25. Such greatly enhanced activity is due to the various valence states of Pt (Pt, n = 0, 2, or 3), forming Pt-O bonds embedded in the framework of TiO and ultrafine Pt metal nanoparticles on the surface of TiO. Such Pt-O bonds could act as the bridges for facilitating the photogenerated electron transfer from the bulk to the surface of TiO with a higher electron carrier density (3.11 × 10 cm), about 2.5 times that (1.25 × 10 cm) of the photoreduced Pt-Ti/TiO sample. Thus, more photogenerated electrons could reach the Pt metal for reducing protons to H.

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