Highly stable multi-layered silicon-intercalated graphene anodes for lithium-ion batteries

© 2020 Cambridge University Press. All rights reserved.To avoid degradation of silicon anodes in lithium-ion batteries (LIBs), the authors report a new two-dimensional multi-layered Si-intercalated rGO (rGO/Si) anode prepared by direct growth of Si into a porous multi-layered reduced graphene oxide (rGO) film. Direct Si deposition onto the porous rGO film allows the Si layers to be intercalated into the film via in situ replacement of the oxygen groups of the multi-layered graphene oxide (GO) with Si through thermal reduction of the GO film. The porous rGO acts as a cushion against the expansion of the Si layer during lithiation, preventing the Si from being pulverized and producing highly stable LIBs11Nsciescopu

Efficient and Stable Solar Hydrogen Generation of Hydrophilic Rhenium-Disulfide-Based Photocatalysts via Chemically Controlled Charge Transfer Paths

© 2020 American Chemical Society.Effective charge separation and rapid transport of photogenerated charge carriers without self-oxidation in transition metal dichalcogenide photocatalysts are required for highly efficient and stable hydrogen generation. Here, we report that a molecular junction as an electron transfer path toward two-dimensional rhenium disulfide (2D ReS2) nanosheets from zero-dimensional titanium dioxide (0D TiO2) nanoparticles induces high efficiency and stability of solar hydrogen generation by balanced charge transport of photogenerated charge carriers. The molecular junctions are created through the chemical bonds between the functionalized ReS2 nanosheets (e.g., -COOH groups) and -OH groups of two-phase TiO2 (i.e., ReS2-C6H5C(≠O)-O-TiO2 denoted by ReS2-BzO-TiO2). This enhances the chemical energy at the conduction band minimum of ReS2 in ReS2-BzO-TiO2, leading to efficiently improved hydrogen reduction. Through the molecular junction (a Z-scheme charge transfer path) in ReS2-BzO-TiO2, recombination of photogenerated charges and self-oxidation of the photocatalyst are restrained, resulting in a high photocatalytic activity (9.5 mmol h-1 per gram of ReS2 nanosheets, a 4750-fold enhancement compared to bulk ReS2) toward solar hydrogen generation with high cycling stability of more than 20 h. Our results provide an effective charge transfer path of photocatalytic TMDs by preventing self-oxidation, leading to increases in photocatalytic durability and a transport rate of the photogenerated charge carrier

Band restructuring of ordered/disordered blue TiO2for visible light photocatalysis

© The Royal Society of Chemistry 2021.Black TiO2with/without noble metals has been proposed for visible light photocatalysis, but such structures still exhibit poor catalytic efficiency. Alternatively, phase-mixed TiO2such as the anatase and rutile phases has been commonly used for visible light catalysis with the inevitable inclusion of noble metals. Herein, we present a noble metal-free visible light photocatalyst, blue TiO2, with type-II band-aligned ordered anatase/disordered rutile structuresviaphase-selective reduction with alkali metals. The changed band alignment in this heterostructure was identified by absorption and ultraviolet photoemission spectroscopy, which was further confirmed by transient charge separation. The band alignment of the type-I and type-II structures was clearly restructured by converting from the ordered to the disordered phase with a prolonged reduction period. We note that after this, light absorbance enhancement was also observed. After initiating the type-I structure in a pristine sample, the type-II structure was organized based on the disordered rutile phase during 3 days of Li-reduction. The type-II disordered rutile TiO2heterostructure exhibits a remarkable photocatalytic performance that is 55 times higher than that of conventional P25 TiO2in the solar-light driven hydrogen evolution reaction, owing to the efficient electron and hole separation of the type-II heterojunction. Furthermore, this restructured heterojunction type-II TiO2required 10 times less Pt as a co-catalyst for comparable photocatalytic performance, compared to Pt decorated type-I pristine anatase/rutile phase-mixed TiO2.11Nsciescopu

Highly efficient nanostructured metal-decorated hybrid semiconductors for solar conversion of CO2 with almost complete CO selectivity

© 2019 Elsevier LtdPhotocatalytic reduction of CO2 into solar fuels is regarded as a promising method to address global warming and energy crisis problems. Although heterostructured hybrid metal oxide catalysts have been used for CO2 reduction, selective control for CO production-only remains the subject of debate. In this paper, we report an absolute selectivity for CO production-only with enhanced photocatalytic ability using Ag-decorated reduced titanium oxide/tungsten hybrid nanoparticles (blue TiO2/WO3–Ag HNPs) at 1166.72 μmol g−1 h−1 with an apparent quantum yield of 34.8%. The construction of a Z-scheme between blue TiO2 and WO3 domains with an excellent band alignment provided remarkably improved separation of photoinduced charges. Importantly, the presence of novel Ag not only produces the highest selectivity up to 100% CO production-only, but also increases the photocatalytic electron reaction rate (2333.44 μmol g−1 h−1)11sciescopu

Phase-Selective Disordered Anatase/Ordered Rutile Interface System for Visible-Light-Driven, Metal-Free CO2 Reduction

Visible-light-driven photocatalytic CO2 reduction using TiO2 that can absorb light of all wavelengths has been sought for over half a century. Herein, we report a phase-selective disordered anatase/ordered rutile interface system for visible-light-driven, metal-free CO2 reduction using a narrow band structure, whose conduction band position matches well with the reduction potential of CO2 to CH4 and CO. A mixed disordered anatase/ordered rutile (Ad/Ro) TiO2 was prepared from anatase and rutile phase-mixed P25 TiO2 at room temperature and under an ambient atmosphere in sodium alkyl amine solutions. The Ad/Ro TiO2 showed a narrow band structure due to multi-internal energy band gaps of Ti3+ defect sites in the disordered anatase phase, leading to high visible light absorption and simultaneously providing fast charge separation through the crystalline rutile phase, which was faster than that of pristine P25 TiO2. The band gap of Ad/Ro TiO2 is 2.62 eV with a conduction band of -0.27 eV, which matches well with the reduction potential of -0.24 VNHE of CO2/CH4, leading to effective electron transfer to CO2. As a result, the Ad/Ro TiO2 provided the highest CH4 production (3.983 μmol/(g h)), which is higher than that of even metal (W, Ru, Ag, and Pt)-doped P25, for CO2 reduction under visible light11sciescopu