In the past few decades, there has been a wide research interest in titanium dioxide (TiO
2
) nanomaterials due to their applications in photocatalytic hydrogen generation and environmental pollution ...removal. Improving the optical absorption properties of TiO
2
nanomaterials has been successfully demonstrated to enhance their photocatalytic activities, especially in the report of black TiO
2
nanoparticles. The recent progress in the investigation of black TiO
2
nanomaterials has been reviewed here, and special emphasis has been given on their fabrication methods along with their various chemical/physical properties and applications.
Recent progress in the preparation, properties and applications of black TiO
2
nanomaterials is reviewed.
Carbon-based supercapacitors can provide high electrical power, but they do not have sufficient energy density to directly compete with batteries. We found that a nitrogen-doped ordered mesoporous ...few-layer carbon has a capacitance of 855 farads per gram in aqueous electrolytes and can be bipolarly charged or discharged at a fast, carbon-like speed. The improvement mostly stems from robust redox reactions at nitrogen-associated defects that transform inert graphene-like layered carbon into an electrochemically active substance without affecting its electric conductivity. These bipolar aqueous-electrolyte electrochemical cells offer power densities and lifetimes similar to those of carbon-based supercapacitors and can store a specific energy of 41 watt-hours per kilogram (19.5 watt-hours per liter).
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BFBNIB, NMLJ, NUK, ODKLJ, PNG, SAZU, UL, UM, UPUK
Abstract Substantially different from traditional combinatorial-treatment of photothermal therapy (PTT) and photodynamic therapy (PDT) by using multi-component nanocomposite under excitation of ...separate wavelength, a novel single near infrared (NIR) laser-induced multifunctional theranostic nanoplatform has been rationally and successfully constructed by a single component black titania ( B –TiO 2− x ) for effective imaging-guided cancer therapy for the first time. This multifunctional PEGylated B –TiO 2− x shows high dispersity/stability in aqueous solution, excellent hemo/histocompatibility and broad absorption ranging from NIR to ultraviolet (UV). Both in vitro and in vivo results well demonstrated that such a novel multifunctional theranostic nanoplaform could achieve high therapeutic efficacy of simultaneous and synergistic PTT/PDT under the guidance of infrared thermal/photoacoustic (PA) dual-modal imaging, which was triggered by a single NIR laser. This research circumvents the conventional obstacles of using multi-component nanocomposites, UV light and high laser power density. Furthermore, negligible side effects to blood and main tissues could be found in 3 months' investigation, facilitating its potential biomedical application.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The photocatalytic activity of TiO2 has aroused a broad range of research effort since 1972. Although TiO2 has a very high efficiency in utilizing ultraviolet light, its overall solar activity is ...very limited due to its wide bandgap (≈3.0−3.2 eV). This is a bottleneck for TiO2 to be applied in the areas ranging from visible‐light photocatalysis and photovoltaics to photo‐electrochemistry and sensors. Recently, the emergence of black TiO2 nanomaterial has triggered world‐wide research interest, because of its substantially enhanced solar absorption and the improved photocatalytic activities. Here, a variety of synthetic strategies of black TiO2 are outlined, and the structural and chemical features, band structures and electronic properties of the black TiO2 nanomaterials are described in details, along with their photocatalytic performances as well as some other new applications.
Black TiO2 nanomaterials have aroused world‐widely scientific interests, owing to their enhanced optical absorption properties and promising visible‐light photocatalysis. The recent progress in the research of black TiO2 is reviewed here, including their synthetic approaches, crystal structure and chemical characters, unique band structure and electronic properties, and their photocatalytic and photovoltaic applications.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The peak fluorescence emission of conventional fluorophores such as organic dyes and inorganic quantum dots is independent of the excitation wavelength. In contrast, the position of the peak ...fluorescence of graphene oxide (GO) in a polar solvent is heavily dependent on the excitation wavelength. The present work has discovered that the strong excitation wavelength dependent fluorescence in GO is originated from the “giant red-edge effect”, which breaks Kasha’s rule. When GO sheets are present in a polar solvent, the solvation dynamics slow down to the same time scale as the fluorescence due to the local environment of the GO sheet. Consequently, the fluorescence peak of GO broadens and red-shifts up to 200 nm with an increase in the excitation wavelength. The giant red-edge effect of GO disappears in a nonpolar solvent, leading to a narrow fluorescence peak that is independent of the excitation wavelength. Discovery of the underlying strong excitation wavelength dependent fluorescence mechanism provides guidelines for the design of graphene oxide-based optical devices.
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IJS, KILJ, NUK, PNG, UL, UM
3D architectures constructed from a tubular graphene network can withstand repeated >95% compression cycling without damage. Aided by intertubular covalent bonding, this material takes full advantage ...of the graphene tube's unique attributes, including complete pre‐ and post‐buckling elasticity, outstanding electrical conductivity, and extraordinary physicochemical stability. A highly connected tubular graphene will thus be the ultimate, structurally robust, ultrastrong, ultralight material.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Here we report a facile low-temperature solvothermal method by using Li-dissolved ethanediamine to prepare uniform hydrogenated blue H-TiO2–x with wide spectrum response. H-TiO2–x possesses a ...distinct crystalline core–amorphous shell structure (TiO2@TiO2–x ) with numerous oxygen vacancies and doped H in the amorphous shell. Efficient solar to chemical energy conversions, likely photocatalytic reduction of CO2, degradation of contaminants, and H2 generation from water splitting can be achieved over this blue titania. Notably, the optimized H-TiO2–x (200) shows high activity of CH4 formation at a rate of 16.2 μmol g–1 h–1 and a selectivity of 79% under full solar irradiation. The kinetic isotope effects measurements reveal that the cleavage of the CO bond from CO2 rather than the O–H bond from H2O is the rate-determining step in CH4 formation. Meanwhile, in situ diffuse reflectance infrared Fourier transform spectroscopy shows the existence of the key intermediate CO2 – species. The formation of intermediate CO2 – indicates that the defective surface of H-TiO2–x can efficiently accelerate the adsorption and chemical activation of the extremely stable CO2 molecule, which makes the single-electron reduction of CO2 to CO2 – easier.
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IJS, KILJ, NUK, PNG, UL, UM
Conductive carbon nitride, as a hypothetical carbon material demonstrating high nitrogen doping, high electrical conductivity, and high surface area, has not been fabricated. A major challenge ...towards its fabrication is that high conductivity requires high temperature synthesis, but the high temperature eliminates nitrogen from carbon. Different from conventional methods, a facile preparation of conductive carbon nitride from novel thermal decomposition of nickel hydrogencyanamide in a confined space is reported. New developed nickel hydrogencyanamide is a unique precursor which provides self‐grown fragments of ⋅NCN⋅ or NCCN and conductive carbon (C‐sp2) catalyst of Ni metal during the decomposition. The final product is a tubular structure of rich mesoporous and microporous few‐layer carbon with extraordinarily high N doping level (≈15 at%) and high extent of sp2 carbon (≈65%) favoring a high conductivity (>2 S cm−1); the ultrahigh contents of nongraphitic nitrogen, redox active pyridinic N (9 at%), and pyrrolic N (5 at%), are stabilized by forming NiN bonds. The conductive carbon nitride harvests a large capacitance of 372 F g−1 with >90% initial capacitance after 10 000 cycles as a supercapacitor electrode, far exceeding the activated carbon electrodes that have <250 F g−1.
Conductive carbon nitride, simultaneously gaining high nitrogen doping and high electrical conductivity, is obtained from novel space‐confined reaction. Nickel hydrogencyanamide provides self‐grown fragments of ⋅NCN⋅ or NC−CN and conductive carbon (C‐sp2) catalyst of Ni metal during the decomposition. The final product is a tubular structure of extraordinarily high N doping level (≈15 at%) and high conductivity (>2 S cm−1).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Overall electrocatalytic water splitting can efficiently and sustainably produce clean hydrogen energy to alleviate the global energy crisis and environmental pollution. Two-dimensional (2D) ...materials with a unique band structure and surface conformation have emerged as promising electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, the intrinsic activities of primitive 2D materials in the catalytic process are still inferior to those of noble metal-based electrocatalysts. Surface defect engineering can modulate the electronic structure of 2D materials and induce new physicochemical properties, promoting their electrocatalytic performance. Herein, this minireview focuses on some recent developments in surface defect engineering, including the contribution of active sites, the derivation of the heterogeneous interface, and the anchoring of active substances, which provides an effective way to further optimize 2D electrocatalysts for water splitting. Furthermore, the typical morphological characteristics, catalytic activity, stability and catalytic mechanism of these 2D electrocatalysts are introduced. We believe that this minireview will help design more efficient and economical electrocatalysts for overall water splitting.
Overall electrocatalytic water splitting can efficiently and sustainably produce clean hydrogen energy to alleviate the global energy crisis and environmental pollution.
The 2H molybdenum disulfide (MoS2), as a stable hexagonal phase, has been one of the most studied transition metal dichalcogenides over the past decades. In the last five years, the metastable phases ...of MoS2 (1T, 1T′, 1T′′, and 1T′′′) have seen a revival of interests. Different from the edge‐sharing MoS6 trigonal prisms in the 2H MoS2 phase, these metastable phases are composed of the edge‐sharing MoS6 octahedra, in which the neighboring Mo−Mo distances differ. Due to the various crystal structures and different electronic configurations of the building MoS6 motifs, these metastable polytypes are endowed with intriguing physical properties and potential applications in diverse fields. In this Review, the recent research progress on metastable MoS2 is summarized, especially with an emphasis on the diverse synthetic approaches and the newly uncovered physical properties. The phase structures and electronic band structures are also outlined. In the end, a perspective of the future investigation on metastable MoS2 is discussed.
S‐Mo‐S three atomic layers with different Mo−S coordination and Mo−Mo bonding result in diverse polymorphs of MoS2 monolayer, the stacking order of which determines the various polytypes of bulk MoS2 crystals. In this Review, the recent research progress on metastable MoS2 is summarized, with an emphasis on the diverse synthetic approaches and the newly uncovered physical properties.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
