Mesoporous TiO nanomaterials have been investigated for decades; however, most endeavors have been focused on the exploration of their potentials in various applications, and the fundamental research for preparing mesoporous TiO in a highly controllable manner remains unfruitful. Herein, we report a facile pressure-driven oriented assembly approach to synthesize an unprecedented type of dehiscent mesoporous TiO microspheres with radial mesopore channels and oriented rutile crystallites. By varying the concentrated HCl amount, we have been able to produce TiO microspheres with well-controlled rutile/anatase phase ratio. By further manipulating the reaction conditions including solvent evaporation time and hydrothermal temperature, the oriented growth with tunable crevices can also be well manipulated. Such dehiscent mesoporous TiO microspheres have exhibited great permeability and excellent photocatalytic properties for H generation. We believe that the high structural complexity and predictability of this method offers great opportunities in enhancing the performance of TiO-based materials. The development of porous materials and their applications has been in great demand recently. However, the progress in rational synthesis of porous semiconductors remains unproductive. Here, we have demonstrated a hydrothermal method to synthesize a novel type of mesoporous TiO microsphere with highly controllable structure. By regulating the synthetic conditions, the mesoporous TiO can be well controlled with oriented mesopores and lattices, tunable crystalline phase, and tailored open crevices. The resulting mesoporous TiO microspheres exhibit excellent penetration properties and photocatalytic activities, which is attributed to their unique mesostructures associated with accessible high surface area and particular architectures. Such a simple method, which is able to fabricate mesoporous TiO with controlled architectures and crystallites, is expected to be applied to produce numerous delicate nanostructures at moderate conditions for potential applications, such as catalysts, energy storage, and biosensors. We have demonstrated a facile hydrothermal approach to synthesize a novel type of mesoporous TiO material with highly controllable structure. By regulating the synthetic conditions, the mesoporous TiO can be well controlled with desired crystallites and architectures. The resulting mesoporous TiO exhibits excellent penetration properties and photocatalytic performance. These unique mesoporous TiO microspheres produced at moderate conditions could afford great opportunities in achieving high performance in various practical applications.

Lan Kun    Wang Ruicong    Zhang Wei    Zhao Zaiwang    Elzatahry Ahmed    Zhang Xingmiao    Liu Yao    Al-Dhayan Dhaifallah    Xia Yongyao    赵东元    

Chem

2018

Transition metal oxides (TMOs)/carbon nanocomposites are promising for high capacity long life lithium ion batteries (LIBs). Herein, we report a mesoporous carbon matrix confinement growth strategy to synthesize ultrasmall WO nanocrystals for lithium storage. In this strategy, WCl and phenolic resins (resol) are co-assembled with amphiphilic diblock copolymer PEO-b-PS into ordered mesostructures through an evaporation induced self-assembly (EISA) process. During the pyrolysis process, the resol molecules can be polymerized and carbonized into amorphous mesoporous carbon matrices, which lock the amorphous W species well. Then, WO nanocrystals are formed and are uniformly distributed in the ordered mesoporous carbon matrix with the increased pyrolysis temperature; moreover, the particle size is well controlled to ∼3 nm under the confinement effect of the carbon matrices. The resultant ordered mesoporous carbon/WO composites show very large pore size (∼11.3 nm), high surface area (∼157 m g), high pore volume (∼0.25 cm g), and WO content of 84%. As an anode material for LIBs, the obtained composites show excellent cycling stability and rate performance. A high specific capacity of 440 mA h g can be achieved after 100 cycles at a current density of 0.1 A g. We believe that such a confinement synthesis strategy is versatile to create TMO-based nanocomposites for outstanding LIBs.

Wang Changyao    Yujuan Zhao    Zhou Lili    Liu Yang    Zhang Wei    Zhao Zaiwang    Hozzein Wael N.    Alharbi Hind M.S.    李炜    赵东元    

Journal of Materials Chemistry A

2018

Extraction of precious metals from low-level sources such as wastewater is of significance for water/wastewater treatment and resource recovery. Herein, we report a composite of nanoscale zero-valent iron in ordered mesoporous carbon (nZVI@C) for rapid reduction and immobilization of precious metals. The iron nanoparticles are anchored by the mesoporous carbon frameworks with active sites partially confined in the carbon cavities. This new material possesses a large surface area (∼500 m g) and highly ordered mesopores (∼5.2 nm). Small-sized (∼16 nm), uniformly dispersed and reactive iron nanoparticles are obtained for the first time. This material exhibits outstanding performance in gold (10 μg L) extraction with >99.9% uptake in less than 5 min. The reclaimed gold nanoparticles are small (<6 nm), stabilized by the presence of both zero-valent iron and mesoporous carbon, exhibiting a high conversion (∼95%) and stability for catalysis. The material thus offers a new strategy for precious metal recovery, as well as the minimization of aggregation and deactivation of reactive nanoparticles.

Wei Teng    范建伟    王玮    Bai Nan    Liu Rui    Liu Yang    邓勇辉    孔彪    杨建平    赵东元     张伟贤   

Journal of Materials Chemistry A

2017

Porous carbon materials doped with nano-sized transition metal carbides and/or metal-nitrogen coordinative sites are promising oxygen reduction electrocatalysts. The doping of such functionalities in carbon materials with desirable concentration, ultra-small size and stable configuration is still a challenge. In this paper, by grinding and pyrolyzing solid mixtures of an amino acid, an iron salt, and a mesoporous silica template, we demonstrate a solvent-free assembly approach to directly anchor both FeC nanoclucters and FeN sites into nitrogen-doped ordered mesoporous graphitic carbon materials. The carbonaceous electrocatalysts are imparted with several fascinating features, namely, highly dispersed ultra-small FeC nanoclusters of 1–3 nm, well-anchored FeN sites, nitrogen-doped well-graphitized carbon frameworks, and ordered mesopores (∼5.4 nm) and high surface areas (>1000 m/g), respectively. The combination of these features makes these electrocatalysts exceptional for oxygen reduction reaction under both alkaline and acidic electrolytes, i.e. superior catalytic activities (e.g. onset and half-wave potentials up to 1.00 and 0.89 V vs. the reversible hydrogen electrode in alkaline solution), outstanding stabilities and excellent methanol tolerance, respectively. An in-depth study has been conducted to identify and characterize the key active sites in these electrocatalysts and to elucidate several important influencing factors to optimize the catalytic performance.

Chen Zhi    Gao Xingmin    Wei Xiangru    Wang Xinxia    Yanguang Li    Wu Tao    Guo Jun    Qinfen Gu    吴铎    Chen Xiao Dong    吴张雄    赵东元    

Carbon

2017

Intricate hollow structures garner tremendous interest due to their aesthetic beauty, unique structural features, fascinating physicochemical properties, and widespread applications. Here, the recent advances in the controlled synthesis are discussed, as well as applications of intricate hollow structures with regard to energy storage and conversion. The synthetic strategies toward complex multishelled hollow structures are classified into six categories, including well-established hard- and soft-templating methods, as well as newly emerging approaches based on selective etching of “soft@hard” particles, Ostwald ripening, ion exchange, and thermally induced mass relocation. Strategies for constructing structures beyond multishelled hollow structures, such as bubble-within-bubble, tube-in-tube, and wire-in-tube structures, are also covered. Niche applications of intricate hollow structures in lithium-ion batteries, Li–S batteries, supercapacitors, Li–O batteries, dye-sensitized solar cells, photocatalysis, and fuel cells are discussed in detail. Some perspectives on the future research and development of intricate hollow structures are also provided.

Liang Zhou    Zhuang Zechao    Zhao Huihui    Lin Mengting    赵东元     Liqiang Mai   

Advanced Materials

2017

Smart surface coatings of silicon (Si) nanoparticles are shown to be good examples for dramatically improving the cyclability of lithium-ion batteries. Most coating materials, however, face significant challenges, including a low initial Coulombic efficiency, tedious processing, and safety assessment. In this study, a facile sol-gel strategy is demonstrated to synthesize commercial Si nanoparticles encapsulated by amorphous titanium oxide (TiO), with core-shell structures, which show greatly superior electrochemical performance and high-safety lithium storage. The amorphous TiO shell (≈3 nm) shows elastic behavior during lithium discharging and charging processes, maintaining high structural integrity. Interestingly, it is found that the amorphous TiO shells offer superior buffering properties compared to crystalline TiO layers for unprecedented cycling stability. Moreover, accelerating rate calorimetry testing reveals that the TiO-encapsulated Si nanoparticles are safer than conventional carbon-coated Si-based anodes.

杨建平    Yun xiao Wang    Wei Li    王联军    Yuchi Fan    Jiang Wan    Wei Luo    王洋    孔彪    Cordelia Selomulya    刘华坤    窦士学    赵东元    

Advanced Materials

2017

Here, we report mesoporous TiO@N-doped carbon composite nanospheres synthesized via a double-surfactant-assisted assembly sol-gel process followed by sequential carbonization of surfactants under a N atmosphere. The resulting TiO@N-doped C composite nanospheres are composed of uniformly distributed TiO nanocrystals with a diameter of ∼8 nm coated by a N-doped carbon layer that was formed by surfactants. Moreover, a large number of connected mesopores were observed in the nanospheres after high-temperature carbonization treatment. The synthesized nanospheres possess a large specific surface area (∼120 m g) and a large pore size (4-40 nm), with a well-defined spherical structure and a diameter in the nanoscale range. As an anode material for lithium-ion batteries (LIB), the mesoporous composite nanospheres delivered a reversible capacity of ∼117 mA h g after 2000 cycles at a current rate as high as 10 C, as well as superior rate capability. The N-doped carbon layers greatly improved the overall electrical conductivity of the mesoporous TiO nanospheres. This study provides a remarkable synthetic route for the preparation of mesoporous TiO-based N-doped carbon composite materials as high-performance anode materials in LIBs.

Zhu Hongwei    Jing Yunke    Manas Pal    Yupu Liu    Liu Yang    Jinxiu Wang    张凡    赵东元    

Nanoscale

2017

This work reports the photodeposition of Ag nanoparticles onto mesoporous TiO (m-TiO) pre-formed by the evaporation-induced self-assembly method. Photoanodes of Ag/m-TiO assembled by electrophoretic disclose a superior photoelectrochemical (PEC) performance for water oxidation reaction related to m-TiO. The photoanodes physicochemical investigations witness the even arrangement of m-TiO nanospheres particles over the substrates. The PEC study displays a steady photocurrent density of 1�mAcm at −1.0�V vs SCE was attained for Ag/m-TiO photoanodes in visible light illumination and it is nearly twofold enhancements in comparison with m-TiO photoanodes. The observed superior PEC nature was attributed to the reduced band-gap energy and charge recombination that caused from the incorporation of plasmonic photodeposited Ag nanoparticles on m-TiO nanospheres photoanodes.

Arunachalam Prabhakarn    Amer Mabrook S.    Mohamed Ghanem    Abdullah mohammed Al-Mayouf    赵东元    

International Journal of Hydrogen Energy

2017

Constructing three-dimensional (3-D) hierarchical mesostructures with unique morphology, pore orientation, single-crystal nature, and functionality remains a great challenge in materials science. Here, we report a confined microemulsion self-assembly approach to synthesize an unprecedented type of 3-D highly ordered mesoporous TiO superstructure (Level-1), which consists of 1 spherical core and 12 symmetric satellite hemispheres epitaxially growing out of the core vertices. A more complex and asymmetric TiO superstructure (Level-2) with 13 spherical cores and up to 44 symmetric satellite hemispheres can also be well manipulated by increasing the size or content of impregnated TiO precursor emulsion droplets. The obtained 3-D mesoporous TiO superstructures have well-defined bouquet-posy-like topologies, oriented hexagonal mesochannels, high accessible surface area (134-148 m/g), large pore volume (0.48-0.51 cm/g), and well single-crystalline anatase walls with dominant (001) active facets. More interestingly, all cylindrical mesopore channels are highly interconnected and radially distributed within the whole superstructures, and all TiO nanocrystal building blocks are oriented grown into a single-crystal anatase wall, making them ideal candidates for various applications ranging from catalysis to optoelectronics. As expected, the bouquet-posy-like mesoporous TiO superstructure supported catalysts show excellent catalytic activity (≥99.7%) and selectivity (≥96%) in cis-semihydrogenation of various alkynes, exceeding that of commercial TiO (P25) supported catalyst by a factor of 10. No decay in the activity was observed for 25 cycles, revealing a high stability of the mesoporous TiO superstructure supported catalyst.

刘勇    Lan Kun    Shushuang Li    刘永梅    孔彪    Wang    Pengfei Zhang    Wang Ruicong    Haili He    Yun Ling    Abdullah Al-Enizi    Elzatahry Ahmed A.    曹勇    陈刚    赵东元    

Journal of the American Chemical Society

2017

As a light-activated noninvasive cancer treatment paradigm, photodynamic therapy (PDT) has attracted extensive attention because of its high treatment efficacy and low side effects. Especially, spatiotemporal control of singlet oxygen (O) release is highly desirable for realizing on-demand PDT, which, however, still remains a huge challenge. To address this issue, a novel switchable near-infrared (NIR)-responsive upconversion nanoprobe has been designed and successfully applied for controlled PDT that can be optically activated by tumor-associated disruption of labile Zn (denoted as Zn hereafter) homeostasis stimuli. Upon NIR irradiation, this theranostic probe can not only quantitatively detect the intracellular endogenous Zn in situ but also selectively generate a great deal of cytotoxic reactive oxygen species (ROS) for efficiently killing breast cancer cells under the activation of excessive endogenous Zn, so as to maximally avoid adverse damage to normal cells. This study aims to propose a new tumor-specific PDT paradigm and, more importantly, provide a new avenue of thought for efficient cancer theranostics based on our designed highly sensitive upconversion nanoprobes. (Figure Presented).

Hu Ping    Rui Wang    周磊    Chen Lei    吴庆生    Han Ming Yong    El-Toni Ahmed Mohamed    赵东元     张凡   

Analytical Chemistry

2017