The rational design and controllable synthesis of strongly coupled inorganic/graphene hybrids represents a long-standing challenge for developing advanced catalysts and energy-storage materials. Here, we report a simple sol-gel method toward creating ultradispersed TiO nanoparticles on graphene with an unprecedented degree of control based on the precise separation and manipulation of nanoparticles nucleated, grown, anchored, and crystallized and the reduction of graphene oxide (GO). The hybrid materials show ultradispersed anatase nanoparticles (∼5 nm), ultrathin thickness (≤3 layers), and a high surface area of ∼229 m/g and exhibit a high specific capacity of ∼94 mA h g at ∼59 C, which is twice as that of mechanically mixed composites (∼41 mA h g), demonstrating the potential of strongly synergistic coupling effects for advanced functional systems. © 2013 American Chemical Society.

李炜    Fei Wang    Shanshan Feng    Jinxiu Wang    Zhenkun Sun    Bin Li    Yuhui Li    杨建平    Ahmed Elzatahry    夏永姚    赵东元    

Journal of the American Chemical Society

2013

Over the past decade, high-quality lanthanide doped upconverting nanoparticles (UCNPs) have been successfully synthesized with the rapid development of nanotechnology and are becoming more prominent in wide application fields, especially in biological sciences. Compared with the traditionally used biological labels such as organic dyes and quantum dots (QDs), upconversion nanomaterials have many advantages, including higher chemical stability, lower toxicity, and higher signal-to-noise ratio. However, the low upconversion efficiency of the lanthanide UCNPs is still the most serious limitation for their applications. Improvements are still needed to optimize upconversion optical properties for further applications. In this review, we summarize the recent progresses for the enhancement of upconversion efficiency of UCNPs and discuss the challenges and opportunities to realize the highly efficient upconversion nanomaterials by systematic comparison of the advantages and shortcomings between UCNPs and QDs & organic dyes from various aspects, such as the luminescence mechanism, multicolor emission, luminescent stability, efficiency, ultra-small nanocrystals fabrication and so on. Furthermore, this review describes the recent progresses of UCNPs based applications in multiplexed encoding, guest delivery and release system, photodynamic therapy (PDT), solar cell, photocatalysis and so on. We also detail the major barriers that currently prevent UCNPs from mainstream applications. © 2013 Elsevier Ltd.

Xiaomin Li    张凡    赵东元    

Nano Today

2013

Core/shell1/shell2/shell3 structured NaGdF:Nd/NaYF/NaGdF:Nd, Yb, Er/NaYF nanocrystals were well designed and synthesized, each of the parts assume respective role and work together to achieve dual-mode upconverting (UC) and downconverting (DC) luminescence upon the low heat effect 800-nm excitation. Nd, Yb, Er tri-doped NaGdF:Nd, Yb, Er UC layer [NIR (800 nm)-to-Visible (540 nm)] with a constitutional efficient 800 nm excitable property were achieved for the in-vitrobioimaging with low auto-fluorescence and photo-damage effects. Moreover, typical NIR (800 nm)-to-NIR (860-895 nm) DC luminescence of Nd has also been realized with this designed nanostructure. Due to the low heat effect, high penetration depth of the excitation and the high efficiency of the DC luminescence, the in-vivohigh contrast DC imaging of a whole body nude mouse was achieved. We believe that such dual-mode luminescence NCs will open the door to engineering the excitation and emission wavelengths of NCs and will provide a new tool for a wide variety of applications in the fields of bioanalysis and biomedical.

Xiaomin Li    Rui Wang    张凡    周磊    Dengke Shen    Chi Yao    赵东元    

Scientific Reports

2013

Built to last: Uniform LiNi Mn O hollow microspheres and microcubes (see picture; scale bars: 1 μm) with nanosized building blocks have been synthesized by a facile impregnation method followed by a simple solid-state reaction. The resultant LiNi Mn O hollow structures deliver a discharge capacity of about 120 mA h g over prolonged cycling and exhibit excellent rate capability. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liang Zhou    赵东元     楼雄文   

Angewandte Chemie - International Edition

2012

Novel double-shelled CoMn O hollow microcubes with nanometer-sized building blocks have been prepared by a facile co-precipitation and annealing method. In virtue of the unique structural features, the resultant CoMn O hollow structures exhibit high specific capacity (μ830 mA h g at 200 mA g ) and good cycling performance as an anode material for lithium-ion batteries. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liang Zhou    赵东元     楼雄文   

Advanced Materials

2012

The hydrothermal stability of the mesoporous silica material SBA-15 was improved by a pre-treatment of 5 mol% ammonium hexafluorosilicate solution with 1 mol% SiO ratio of (NH ) SiF and SBA-15. The modified SBA-15 kept its ordered meso-structure well even when kept under boiling water for 14 d or 100% H O stream at 800°C for 12 h, and still had BET surface areas as high as 310 and 213 m /g, respectively, after these treatments. The possible reasons for the stabilization were that the surface defects of SBA-15 were partially repaired by silicon insertion and some silicon hydroxyls were replaced by F ions. Larger amounts of ammonium hexafluorosilicate did not give more stabilization.

Song Mingjuan    Zou Chenglong    牛国兴    赵东元    

Cuihua Xuebao/Chinese Journal of Catalysis

2012

We demonstrate for the first time the controlled Sn-doping in TiO nanowire (NW) arrays for photoelectrochemical (PEC) water splitting. Because of the low lattice mismatch between SnO and TiO , Sn dopants are incorporated into TiO NWs by a one-pot hydrothermal synthesis with different ratios of SnCl and tetrabutyl titanate, and a high acidity of the reactant solution is critical to control the SnCl hydrolysis rate. The obtained Sn-doped TiO (Sn/TiO ) NWs are single crystalline with a rutile structure, and the incorporation of Sn in TiO 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 NW photoanodes with different Sn doping ratios shows that the photocurrent increases first with increased Sn doping level to >2.0 mA/cm at 0 V vs Ag/AgCl under 100 mW/cm simulated sunlight illumination up to ∼100% enhancement compared to our best pristine TiO NW photoanodes and then decreases at higher Sn doping levels. Subsequent annealing of Sn/TiO NWs in H 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 NW photoanodes are highly stable in PEC conversion and thus can serve as a potential candidate for pure TiO materials in a variety of solar energy driven applications. © 2012 American Chemical Society.

Ming Xu    Peimei Da    Haoyu Wu    赵东元     郑耿峰   

Nano Letters

2012

Hejazifar Mahtab    Azizian Saeid    Sarikhani Hassan    李强    赵东元    

Journal of Analytical and Applied Pyrolysis

2012

Ordered mesoporous graphitized pyrolytic carbons have been successfully synthesized via direct chemical vapor deposition from methane with mesoporous silicas as the hard templates. The synthesis procedure is quite simple without use of solvent, catalyst or carrying gas, but efficient for producing mesoporous carbon materials. The whole carbon deposition process is comprehensively studied and illustrated, and the mesostructure regularity, pore architecture, and porosity of the resultant carbon materials can be tuned by simply manipulating the deposition time. The morphological, structural, textural and framework properties of the obtained carbon materials are extensively studied, clearly demonstrating the special features including controllable mesostructures, variable mesopore arrangements, large pore volumes (up to 2.3 cm g ), high surface areas (up to 750 m g ) and highly graphitized pore walls with preferred (002) crystal plane orientation. Simple thermal treatment pathways for further promoting the graphitization degree are also proposed. These mesoporous graphitic carbon materials hold promising potential for electrochemical energy storage and conversion applications. They can serve as excellent supports for platinum nanoparticles for oxygen reduction, showing greatly enhanced Pt utilization, activity, methanol tolerance and long-term stability compared to an activated-carbon-supported Pt catalyst. They can be adopted as electrode materials for lithium-ion batteries, showing a high reversible capacity up to ∼340 mAh g and a good cyclic stability. They can also be utilized as electrode materials without the use of any conductive additives for supercapacitors under non-aqueous systems, showing a specific capacitance of ∼40 F g with high Coulombic efficiency and excellent rate performance. © 2012 The Royal Society of Chemistry.

吴张雄    李炜    夏永姚    Paul Webley    赵东元    

Journal of Materials Chemistry

2012

Control of porosity and structure and modification of surface and framework are the golden rules to adapt carbon materials to targeted applications. The former has been fairly well developed for the soft-templated FDU-type mesoporous carbons while there is still a large need for the latter. In this paper, a simple post-synthetic route is adopted to incorporate nitrogen-containing functionalities into the frameworks of these carbon materials. The basic principle relies on the confinement of melamine molecules in the mesochannels of an ordered mesoporous carbon matrix such that they self-condense into carbon nitride uniformly dispersed under a heat treatment at ∼500 °C and subsequently lead to the formation of mesoporous nitrogen-enriched carbon materials at 700-900 °C with well-retained ordered mesostructure and high surface area. The structure, porosity, composition and the nitrogen-containing functionalities are extensively studied. The integration of regular and open mesostructure, uniform and large mesopore size, high mesoporosity, and nitrogen enrichment makes these materials highly efficient for phenol removal, not only through physisorption with fast adsorption kinetics and large capacity but also by a newly found photo-degradation property with remarkable catalytic activity. Furthermore, the mesoporous nitrogen-enriched carbons deliver promising properties for CO capture with greatly enhanced heats of adsorption and well-retained high capacity. Given that the FDU-type mesoporous carbon materials hold variable structures, tunable pore sizes, flexible morphologies and an ease for large-scale synthesis, the success in nitrogen-enrichment would significantly accelerate the progress of their practical applications in pollution control, environment management, supercapacitors and fuel cells. © 2012 The Royal Society of Chemistry.

吴张雄    Paul Webley    赵东元    

Journal of Materials Chemistry

2012