Showing papers by "Wuhan University of Technology published in 2011"
TL;DR: High photocatalytic H(2)-production activity is attributed predominantly to the presence of graphene, which serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carriers from CdS nanoparticles.
Abstract: The production of clean and renewable hydrogen through water splitting using photocatalysts has received much attention due to the increasing global energy crises. In this study, a high efficiency of the photocatalytic H2 production was achieved using graphene nanosheets decorated with CdS clusters as visible-light-driven photocatalysts. The materials were prepared by a solvothermal method in which graphene oxide (GO) served as the support and cadmium acetate (Cd(Ac)2) as the CdS precursor. These nanosized composites reach a high H2-production rate of 1.12 mmol h–1 (about 4.87 times higher than that of pure CdS nanoparticles) at graphene content of 1.0 wt % and Pt 0.5 wt % under visible-light irradiation and an apparent quantum efficiency (QE) of 22.5% at wavelength of 420 nm. This high photocatalytic H2-production activity is attributed predominantly to the presence of graphene, which serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carrier...
2,212 citations
TL;DR: Graphene and graphitic carbon nitride composite photocatalysts were prepared by a combined impregnation−chemical reduction strategy involving polymerization of melamine in the presence of graphene oxide (precursors) and hydrazine hydrate (reducing agent), followed by thermal treatment at 550 °C under flowing nitrogen as mentioned in this paper.
Abstract: Graphene and graphitic carbon nitride (g-C3N4) composite photocatalysts were prepared by a combined impregnation−chemical reduction strategy involving polymerization of melamine in the presence of graphene oxide (precursors) and hydrazine hydrate (reducing agent), followed by thermal treatment at 550 °C under flowing nitrogen. The resulting graphene/g-C3N4 composite photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, UV−visible spectrophotometry, nitrogen adsorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. The transient photocurrent response was measured for several on−off cycles of intermittent irradiation. The effect of graphene content on the rate of visible-light photocatalytic hydrogen production was studied for a series of graphene−graphitic carbon nitride composite samples containing Pt as a cocatalyst in methanol aqueous solutions. This study shows that graphene sheets a...
1,660 citations
TL;DR: It is demonstrated that constructing 3D hierarchical heterostructures can improve electrochemical properties and 'Oriented attachment' and 'self-assembly' crystal growth mechanisms are proposed to explain the formation of the heterostructure.
Abstract: The construction of three-dimensional hierarchical heterostructures can lead to improved electrochemical properties. Mai et al. synthesize a three-dimensional multicomponent oxide, MnMoO4/CoMoO4, which is used to produce a supercapacitor with enhanced performance.
1,008 citations
TL;DR: It was found for the first time that decreasing the relative concentration ratio of bulk defects to surface defects in TiO(2) nanocrystals could significantly improve the separation efficiency of photogenerated electrons and holes, thus significantly enhancing the photocatalytic efficiency.
Abstract: TiO2 nanocrystals with tunable bulk/surface defects were synthesized and characterized with TEM, XRD, BET, positron annihilation, and photocurrent measurements. The effect of defects on photocatalytic activity was studied. It was found for the first time that decreasing the relative concentration ratio of bulk defects to surface defects in TiO2 nanocrystals could significantly improve the separation efficiency of photogenerated electrons and holes, thus significantly enhancing the photocatalytic efficiency.
934 citations
TL;DR: This feature article highlights some of the recent advances in the last four years, including the various smart routes to construct rough surfaces, and a lot of chemical modifications which lead to superhydrophobicity.
840 citations
TL;DR: A novel visible-light-driven photocatalyst was designed based on photoinduced interfacial charge transfer (IFCT) through surface modification of ZnS porous nanosheets by CuS and for the first time exhibits a facile method for enhancing H(2)-production activity by photoinduced IFCT.
Abstract: Visible light photocatalytic H2 production through water splitting is of great importance for its potential application in converting solar energy into chemical energy. In this study, a novel visible-light-driven photocatalyst was designed based on photoinduced interfacial charge transfer (IFCT) through surface modification of ZnS porous nanosheets by CuS. CuS/ZnS porous nanosheet photocatalysts were prepared by a simple hydrothermal and cation exchange reaction between preformed ZnS(en)0.5 nanosheets and Cu(NO3)2. Even without a Pt cocatalyst, the as-prepared CuS/ZnS porous nanosheets reach a high H2-production rate of 4147 μmol h–1 g–1 at CuS loading content of 2 mol % and an apparent quantum efficiency of 20% at 420 nm. This high visible light photocatalytic H2-production activity is due to the IFCT from the valence band of ZnS to CuS, which causes the reduction of partial CuS to Cu2S and thus enhances H2-production activity. This work not only shows a possibility for substituting low-cost CuS for nobl...
819 citations
TL;DR: The proposed mechanism for the observed photocatalytic performance of TiO(2) nanosheets, modified with a small amount of graphene, was further confirmed by photoluminescence spectroscopy and transient photocurrent response and for the first time shows a significant enhancement in the H(2)-production activity by using metal-free carbon material as an effective co-catalyst.
Abstract: Graphene-modified TiO2 nanosheets with exposed (001) facets (graphene/TiO2) were prepared by microwave-hydrothermal treatment of graphene oxide (GO) and hydrothermally synthesized TiO2 nanosheets with exposed (001) facets in an ethanol–water solvent. These nanocomposite samples showed high photocatalytic H2-production activity in aqueous solutions containing methanol, as sacrificial reagent, even without Pt co-catalyst. The optimal graphene content was found to be ∼1.0 wt%, giving a H2-production rate of 736 μmol h−1 g−1 with a quantum efficiency (QE) of 3.1%, which exceeded the rate observed on pure TiO2 nanosheets by more than 41 times. This high photocatalytic H2-production activity is due to the deposition of TiO2 nanosheets on graphene sheets, which act as an electron acceptor to efficiently separate the photogenerated charge carriers. The observed enhancement in the photocatalytic activity is due to the lower absolute potential of graphene/graphene˙− (−0.08 V vs. SHE, pH = 0) in comparison to the conduction band (−0.24 V) of anatase TiO2, meanwhile the aforementioned absolute value is higher than the reduction potential of H+ (0 V), which favors the electron transfer from the conduction band (CB) of TiO2 to graphene sheets and the reduction of H+, thus enhancing photocatalytic H2-production activity. The proposed mechanism for the observed photocatalytic performance of TiO2 nanosheets, modified with a small amount of graphene, was further confirmed by photoluminescence spectroscopy and transient photocurrent response. This work not only shows a possibility for the utilization of low cost graphene sheets as a substitute for noble metals (such as Pt) in the photocatalytic H2-production but also for the first time shows a significant enhancement in the H2-production activity by using metal-free carbon material as an effective co-catalyst.
721 citations
TL;DR: A review of the existing strategies for the synthesis of anatase TiO2 micro-and nanosheets with exposed high-energy {001} facets is presented in this article.
Abstract: Control of the surface structure of inorganic materials, in particular titania (TiO2), by chemical processes under nonequilibrium conditions is of growing interest from scientific and utilitarian viewpoints. Titania is one of the most important materials because of its unique surface, electronic, and photocatalytic properties, which make this material applicable in many areas of science and technology ranging from adsorption, catalysis and photocatalysis to biomedicine, environmental monitoring and cleanup, energy conversion and storage, etc. Here we review the existing strategies for the synthesis of anatase TiO2 micro- and nanosheets with exposed high-energy {001} facets and for the assembly of these nanosheets into various hierarchical structures. The {001} facets are stabilized by specific capping agents (typically, fluoride), which are used to control the growth of titania crystals. The presence of high-energy facets in titania improves significantly its adsorption, electronic, and photocatalytic pro...
662 citations
TL;DR: The results indicated that the formation rate of (·)OH on the surface of irradiated commercial Degussa P25 (P25) was much higher than that of other semiconductor.
584 citations
TL;DR: In this article, a simple precipitation method using Degussa P25 TiO2 powder (P25) as a support and copper nitrate as a precursor was used to obtain a photocatalytic H2-production rate of 3418 μmol h−1 g−1 with a quantum efficiency of 13.9%.
Abstract: Cu(OH)2 cluster-modified TiO2 (Cu(OH)2/TiO2) photocatalysts were prepared by a simple precipitation method using Degussa P25 TiO2 powder (P25) as a support and copper nitrate as a precursor. Low-power ultraviolet light emitting diodes (UV-LEDs) were used as the light source for a photocatalytic water splitting reaction. The prepared samples show especially high photocatalytic H2-production activity from aqueous solutions containing ethylene glycol as sacrificial reagent even without a Pt co-catalyst. The optimal Cu(OH)2 loading content was found to be 0.29 mol%, giving an H2-production rate of 3418 μmol h−1 g−1 with a quantum efficiency (QE) of 13.9%, which exceeded the rate on pure TiO2 by more than 205 times. This high photocatalytic H2-production activity is attributed to the presence of Cu(OH)2 clusters on the surface of the TiO2. The potential of Cu(OH)2/Cu (Cu(OH)2 + 2e− = Cu + 2OH−, Eo = −0.224 V) is slightly lower than conduction band (−0.26 V) of anatase TiO2, whilst being higher than the reduction potential of H+ (2H+ + 2e− = H2, Eo = −0.000 V), which favors the electron transfer from the CB of TiO2 to Cu(OH)2, and the reduction of H+, thus enhancing photocatalytic H2-production activity. This work not only shows a possibility for the utilization of low cost Cu(OH)2 clusters as a substitute for noble metals (such as Pt) in photocatalytic H2-production, but also for the first time exhibits a facile method for enhancing H2-production activity by using hydroxide as a co-catalyst .
535 citations
TL;DR: In this paper, a self-organized BiOI/TiO2 nanotube arrays (NTs) were prepared by coating biOI on the tube wall of the selforganized TiO2 NTs using a novel impregnating−hydroxylation method.
Abstract: p−n junction BiOI/TiO2 nanotube arrays (NTs) were prepared by coating BiOI on the tube wall of the self-organized TiO2 NTs using a novel impregnating−hydroxylation method. The as-prepared samples w...
TL;DR: In this study, only these chemically bonded CNTs/TiO(2) nanocomposites with appropriate loading amounts favor the separation of photogenerated electron-hole pairs and decrease their recombination rate and thus display significantly enhanced photocatalytic activity for degrading acetone in air under UV irradiation, as compared with pristine TiO( 2) counterparts and commercial P25 photocatalyst.
Abstract: Mesoporous multiwalled carbon nanotubes/titanium dioxide (CNTs/TiO2) nanocomposites with low loading amounts (0–0.5 wt%) of CNTs embedded inside mesoporous TiO2 aggregates has been prepared by a simple one-pot hydrothermal method using titanium sulfate as titanium source. The as-prepared CNTs/TiO2 samples are carefully characterized, analyzed and discussed. In contrast to previous reports with high CNT loading, our results indicate that a low CNT loading slightly influences the textural properties (including crystallite size, degree of crystallinity, specific surface areas, and pore volume etc.) and UV-light absorption of the mesoporous TiO2 aggregates. The SEM and TEM results demonstrate that the CNTs are mostly embedded in the mesoporous TiO2 aggregates. Moreover, chemical bonds are formed at the interface between CNTs and TiO2, which is confirmed by the Raman, IR and XPS analyses. Significantly, we point out that PL analysis in terms of intensity of PL signals seems to not be a reliable way to monitor the recombination rate in the CNTs/TiO2 composite, due to the quenching effect of CNTs. Instead, the analysis of transient photocurrent responses is introduced, which definitely reflects CNTs as fast electron transfer channels in chemically-bonded CNTs/TiO2 composites with low CNT loading. Notably, the positive synergy effects of CNTs and TiO2 depend on both the CNT loading amount and the state of interfacial contacts. In our study, only these chemically bonded CNTs/TiO2 nanocomposites with appropriate loading amounts ( 0.1 wt%) results in a decrease in photocatalytic activity; a simple mechanical mixing of CNTs and TiO2 without forming chemical bonds at the interface also results in inferior photocatalytic performance.
TL;DR: In this article, a novel hydrothermal approach is developed for the first time to synthesize hierarchical BiVO4/Bi2O2CO3 nanocomposites with reactive crystalline facets using urea as a morphology mediator.
Abstract: A novel hydrothermal approach is developed for the first time to synthesize hierarchical BiVO4/Bi2O2CO3 nanocomposites with reactive crystalline facets using urea as a morphology mediator. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, N2 absorption–desorption isotherms and UV–visible diffuse reflectance spectroscopy. The photocatalytic activity of the as-prepared samples was evaluated towards degradation of Rhodomine B (RhB) by visible-light. Our results indicate that both physical parameters and associated photocatalytic activity of BiVO4/Bi2O2CO3 nanocomposites can be tuned by urea concentration and reaction time in the synthesis process. With increasing urea concentration, the specific surface area, pore volume and average pore size increase. Compared to BiVO4 and Bi2O2CO3 bulk counterpart, BiVO4/Bi2O2CO3 nanocomposites show enhanced photocatalytic degradation activity of RhB. The mechanisms for the formation of BiVO4/Bi2O2CO3 nanocomposites and enhanced photoreactivity are discussed.
TL;DR: In this article, a functionalized graphene oxide Nafion nanocomposites (F-GO/Nafion) are presented as a potential proton exchange membrane (PEM) replacement for high temperature PEM fuel cell applications.
Abstract: Functionalized graphene oxide Nafion nanocomposites (F-GO/Nafion) are presented as a potential proton exchange membrane (PEM) replacement for high temperature PEM fuel cell applications. The GO nanosheets were produced from natural graphite flakes by the modified Hummer’s method and then functionalized by using 3-mercaptopropyl trimethoxysilane (MPTMS) as the sulfonic acid functional group precursor. F-GO/Nafion composite membranes were fabricated by a simplistic solution casting method. Several physicochemical characterization techniques were applied to provide insight into the specific structure and morphology, functional groups, water uptake, and ionic conductivities of the membranes. Proton conductivity and single cell test results demonstrated significant improvements for F-GO/Nafion membranes (4 times) over recast Nafion at 120 °C with 25% humidity.
TL;DR: In this paper, carbon self-doped TiO2 sheets (CTS) with exposed {001} facets were synthesized by hydrothermal treatment of titanium carbide (TiC) in a HNO3-HF mixed aqueous solution.
Abstract: Novel carbon self-doped TiO2 sheets (CTS) with exposed {001} facets were synthesized by hydrothermal treatment of titanium carbide (TiC) in a HNO3-HF mixed aqueous solution. In this synthesis TiC was used as a precursor of TiO2 and a source of C, which was self-doped into the lattice of anatase sheets. The resulting CTS materials were examined as photocatalysts for degradation of methylene blue (MB) in aqueous solutions under visible light irradiation (λ > 420 nm). These materials exhibited an enhanced absorption in the whole visible-light region and an obvious red shift at the absorption edges. The first-principle density functional theory (DFT) calculations provided a further confirmation for the aforementioned red shift and for noticeable reduction of the band gap of C-doped TiO2 sheets with exposed {001} facets. The photocatalytic studies of CTS showed that these sheets exhibited much higher photocatalytic activity than that of the C-doped TiO2 nanoparticles due to the presence of exposed {001} facets. In addition, separation of CTS after photocatalytic reaction from slurry by filtration or sedimentation and their reuse is easier in comparison to conventional nanosized powder photocatalysts.
TL;DR: In this paper, the effect of Ni(OH)2 cluster loading content on the photocatalytic hydrogen production rates of the as-prepared samples in methanol aqueous solution was investigated.
Abstract: Ni(OH)2 cluster-modified TiO2 (Ni(OH)2/TiO2) nanocomposite photocatalysts were fabricated by a simple precipitation method using Degussa P25 TiO2 powder (P25) as support and Ni(NO3)2 as precursor. The effect of Ni(OH)2 cluster loading content on the photocatalytic hydrogen production rates of the as-prepared samples in methanol aqueous solution was investigated. The results showed that the photocatalytic H2-production activity of TiO2 was significantly enhanced by loading Ni(OH)2 clusters. The optimal Ni(OH)2 loading content was found to be 0.23 mol %, giving a H2-production rate of 3056 μmol h−1 g−1 with quantum efficiency (QE) of 12.4%, exceeding that on pure TiO2 by more than 223 times. This high photocatalytic H2-production activity is due to the deposition of Ni(OH)2 clusters on the surface of TiO2. The enhanced mechanism is because the potential of Ni2+/Ni (Ni2+ + 2e− = Ni, Eo = −0.23 V) is slightly lower than conduction band (CB) (−0.26 V) of anatase TiO2, meanwhile higher than the reduction potent...
TL;DR: The low salt roasting-cyclic oxidation (LSRCO) technique as discussed by the authors has been proposed to extract vanadium from coal in the past few years and has shown promising results.
TL;DR: In this paper, a facile method for surface acetylation of cellulose nanocrystals (CN) was developed by reaction with acetic anhydride and hydroxyl groups on the surface of CN.
TL;DR: The as-prepared Ni(OH)(2) and NiO nanosheets are found to be effective adsorbents for the removal of Congo red pollutant from wastewater as a result of their unique hierarchical porous structures and high specific surface areas.
TL;DR: In this paper, a Ni(OH)2-modified CdS nanorod-type composite photocatalyst was presented, which achieved a visible-light H2-production rate of 5085 μmol h−1 g−1 corresponding to 28% quantum efficiency (QE) at 420 nm.
TL;DR: Nitrogen self-doped TiO(2) nanosheets with exposed {001} facets were synthesized by solvothermal treatment of TiN in a HNO(3)-HF ethanol solution and exhibited much higher visible-light photocatalytic H(2)-production activity.
TL;DR: In this paper, a hierarchical flower-like C-doped ZnO superstructures (ZnO flowers) assembled from porous nanosheets are obtained by pyrolysis of morphology-analogous Zn5(CO3)2(OH)6 precursors.
Abstract: Hierarchical flower-like C-doped ZnO superstructures (ZnO flowers) assembled from porous nanosheets are obtained by pyrolysis of morphology-analogous Zn5(CO3)2(OH)6 precursors. The prepared ZnO flowers are characterized by X-ray diffraction, thermogravimetic and differential scanning calorimeter analysis, scanning electron microscopy, transmission electron microscopy, N2 sorption measurements, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The production of OH radicals on the ZnO surface under visible-light irradiation is detected by a photoluminescence technique using terephthalic acid as a probe molecule. The visible-light photocatalytic activity is evaluated by photocatalytic decomposition of the dye RhB in aqueous solution. The hierarchical organization of nanosheets, the multimode voids between and within porous nanosheets, together with annealing-induced in situ carbon self-doping within the ZnO lattice, account for the enhanced light-absorption capacity, extended light-response range and thus better photocatalytic activity of the ZnO flowers. Furthermore, first-principle density functional theory (DFT) calculation further confirms the C-doping induced red shift in the absorption edges of C-doped ZnO flowers.
TL;DR: Several successful approaches for the design and preparation of bioactive surfaces based on different types of anti-fouling/spacer materials are summarized.
TL;DR: The results show that nitrogen and sulfur atoms were successfully incorporated into the lattice of TiO(2), which resulted in N-S-TiO (2) samples exhibiting stronger absorption in the UV-visible range with a red shift in the band gap transition, and first-principle DFT calculations further confirm that N and S co-dopants can induce the formation of new energy levels in the bands gap.
Abstract: Nitrogen and sulfur co-doped TiO(2) nanosheets with exposed {001} facets (N-S-TiO(2)) were prepared by a simple mixing-calcination method using the hydrothermally prepared TiO(2) nanosheets powder as a precursor and thiourea as a dopant. The resulting samples were characterized by transmission electron microscope, X-ray diffraction, N(2) adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and UV-Vis absorption spectroscopy. The electronic properties of N,S co-doped TiO(2) were studied using the first-principle density functional theory (DFT). The photocatalytic activity of N-S-TiO(2) was evaluated by degradation of 4-chlorophenol (4-CP) aqueous solution under visible light irradiation. The production of hydroxyl radicals (˙OH) on the surface of visible-light-irradiated samples was detected by photoluminescence technique using terephthalic acid as a probe molecule. The results show that nitrogen and sulfur atoms were successfully incorporated into the lattice of TiO(2), which resulted in N-S-TiO(2) samples exhibiting stronger absorption in the UV-visible range with a red shift in the band gap transition. The first-principle DFT calculations further confirm that N and S co-dopants can induce the formation of new energy levels in the band gap, which is associated with the response of N-S-TiO(2) nanosheets to visible light irradiation. Surprisingly, pure TiO(2) nanosheets show the visible-light photocatalytic activity for the degradation of 4-CP mainly due to the substrate-surface complexation of TiO(2) and 4-CP, which results in extending absorption of titania to visible light region through ligand-to-titanium charge transfer. The N-S-TiO(2) samples studied exhibited an enhanced visible-light photocatalytic activity than pure TiO(2). Especially, the doped TiO(2) sample at the nominal weight ratio of thiourea to TiO(2) powder of 2 showed the highest photocatalytic activity, which was about twice greater than that of Degussa P25. The enhanced activity of N-S-TiO(2) can be primarily attributed to the synergetic effects of two factors including the intense absorption in the visible-light region and the exposure of highly reactive {001} facets of TiO(2) nanosheets. The former is beneficial for the photogeneration of electrons and holes participating in the photocatalytic reactions, and the latter facilitates adsorption of 4-CP molecules on the surface of TiO(2) nanosheets.
TL;DR: This work shows not only the possibility of using CuO clusters as a substitute for noble metals in the photocatalytic H(2)-production but also demonstrates a new way for enhancing hydrogen production activity by quantum size effect.
TL;DR: In this article, the evaporation-induced self-assembly (EISA) in ethanolic solution of a triblock copolymer (Pluronic P123) was explored for the synthesis of ordered mesoporous alumina (MA) and supported metal oxides, using aluminum isopropoxide, aluminum chloride, and aluminum nitrate nonahydrate as aluminum precursors, and nickel, magnesium, iron, chromium, copper, cerium, lanthanum, yttrium, calcium, tin chlorides, or nitrates as metal precurs
Abstract: The evaporation-induced self-assembly (EISA) in ethanolic solution of a triblock copolymer (Pluronic P123) is explored for the synthesis of ordered mesoporous alumina (MA) and MA-supported metal oxides, using aluminum isopropoxide, aluminum chloride, and aluminum nitrate nonahydrate as aluminum precursors, and nickel, magnesium, iron, chromium, copper, cerium, lanthanum, yttrium, calcium, tin chlorides, or nitrates as metal precursors. The as-synthesized mesoporous oxides were characterized by a variety of techniques, such as thermogravimetry, Fourier transform infrared spectroscopy, nitrogen adsorption, small- and wide-angle X-ray diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectrometry, elemental mapping, and CO2 and NH3 temperature-programmed desorption. It is shown that the EISA strategy in the presence of polymeric template not only is well-suited for the synthesis of ordered MAs and MA-supported metal oxides with tailored adsorption and framework properties...
TL;DR: In this article, a plasmonic Z-scheme photocatalytic mechanism was proposed for high efficiency visible-light photocatalyst, where noble-metal nanoparticles (such as Ag) can act as an active component for the design of high-efficiency PLAs.
Abstract: The Z-scheme has been proven to be an effective strategy to develop a high-efficiency visible-light photocatalyst. However, the visible-light-responding active component in the Z-scheme system is usually restricted to semiconductor materials sensitive to visible light. On the other hand, noble-metal nanoparticles (such as Ag) can act as an active component for the design of high-efficiency plasmonic photocatalysts due to their strong absorption in the visible light region. In this study, H2WO4·H2O/Ag/AgCl composite nanoplates were prepared by a one-step ionic reaction between Ag8W4O16/Ag nanorods and HCl aqueous solution. The photocatalytic activity experiments indicated that the H2WO4·H2O/Ag/AgCl composite nanoplates exhibited a much higher photocatalytic activity than the one-component (H2WO4·H2O) or two-component (such as Ag/AgCl and H2WO4·H2O/Ag) photocatalysts. On the basis of photocatalytic activity and band structure analysis, a plasmonic Z-scheme photocatalytic mechanism is proposed; namely, two-s...
TL;DR: TiO( 2) films composed of flower-like TiO(2) microspheres with exposed {001} facets were synthesized by a simple one-pot hydrothermal method and exhibited tunable photocatalytic selectivity towards decomposition of azo dyes in water.
TL;DR: In this article, a monoclinic layered structure of titanium niobium oxide (TiNb2O7) was synthesized by a solid state reaction method as an anode candidate for Li-ion batteries.
Abstract: Titanium niobium oxide (TiNb2O7) with a monoclinic layered structure has been synthesized by a solid state reaction method as an anode candidate for Li-ion batteries. The TiNb2O7 electrode shows a lithium storage capacity of 281 mAh g−1with an initial coulombic efficiency as high as 93% at a current density of 30 mA g−1 (ca. 0.1C). The average lithium insertion voltage is about 1.64 V vs.Li/Li+ at a voltage range of 0.8–3.0 V. The electrodes exhibit small voltage hysteresis (c.a. 0.1 V at 30 mA g−1) and good capacity retention. Such superior electrochemical performance of TiNb2O7 makes it one of the most promising anode materials to replace spinel Li4Ti5O12 for applications in hybrid vehicles and large scale stationary Li-ion batteries. In addition, we demonstrate crystal structures of TiNb2O7 and lithiated TiNb2O7 using advanced spherical-aberration-corrected scanning transmission electron microscopy (STEM), to picture the lattice sites occupied by the Li, Ti, Nb and O atoms at atomic-scale. Possible lithiation/delithiation processes and reaction mechanisms are revealed in consistence with first-principles prediction.