Like surfactants with tunable hydrocarbon chain length, Janus nanoparticles also possess the ability to stabilize emulsions. The volume ratio between the hydrophilic and hydrophobic domains in a single Janus nanoparticle is very important for the stabilization of emulsions, which is still a great challenge. Herein, dual-mesoporous FeO@mC&mSiO Janus nanoparticles with spatial isolation of hydrophobic carbon and hydrophilic silica at the single-particle level have successfully been synthesized for the first time by using a novel surface-charge-mediated selective encapsulation approach. The obtained dual-mesoporous FeO@mC&mSiO Janus nanoparticles are made up of a pure one-dimensional mesoporous SiO nanorod with tunable length (50-400 nm), 100 nm wide and 2.7 nm mesopores and a closely connected mesoporous FeO@mC magnetic nanosphere (150 nm diameter, 10 nm mesopores). As a magnetic "solid amphiphilic surfactant", the hydrophilic/hydrophobic ratio can be precisely adjusted by varying the volume ratio between silica and carbon domains, endowing the Janus nanoparticles surfactant-like emulsion stabilization ability and recyclability under a magnetic field. Owing to the total spatial separation of carbon and silica, the Janus nanoparticles with an optimized hydrophilic/hydrophobic ratio show spectacular emulsion stabilizing ability, which is crucial for improving the biphasic catalysis efficiency. By selectively anchoring catalytic active sites into different domains, the fabricated Janus nanoparticles show outstanding performances in biphasic reduction of 4-nitroanisole with 100% conversion efficiency and 700 h high turnover frequency for biphasic cascade synthesis of cinnamic acid.
Zhao Tiancong Zhu Xiaohang Hung Chin-Te Wang Peiyuan Elzatahry Ahmed Al-Khalaf Areej Abdulkareem Hozzein Wael N. 张凡 Xiaomin Li 赵东元
Journal of the American Chemical Society
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
Alumina materials have widely been used in industrial fields, such as catalysis and adsorption. However, due to the fast sol-gel process and complicated crystalline-phase transformation, the synthesis of alumina materials with both highly ordered mesostructures and crystallized frameworks remains a great challenge. Herein, we report a novel vesicle-aggregation-assembly strategy to prepare highly ordered mesoporous γ-alumina microspheres with unique shifted double-diamond networks for the first time, by using diblock copolymer poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA) as a template and aluminum isopropoxide as a precursor in a tetrahydrofuran (THF)/hydrochloric acid binary solvent. During the gradual evaporation of THF and HO, the as-made Al-based gel/PEO-b-PMMA composites can be obtained through a co-assembly process based on the hydrogen bonding interaction between hydroxyl groups of alumina oligomers and PEO segments of the diblock copolymers. The formed composites exhibit a spherical morphology with a wide size distribution (diameter size 1-12 μm). Furthermore, these composite microspheres possess an inverse bicontinuous cubic mesostructure (double diamond, Pn3m) with Al-based gel buried in the PEO-b-PMMA matrix in the form of two intertwined but disconnected networks. After a simple calcination at 900 °C in air, the structure of the resultant mesoporous alumina changes to a relatively low symmetry (shifted double diamond, Fd3m), ascribed to the shifting of the two alumina networks due to loss of the templates. Meanwhile, the unit cell size of the alumina mesostructure decreases from ∼131 to ∼95 nm. The obtained ordered mesoporous alumina products retain the spherical morphology and possess ultra-large mesopores (∼72.8 nm), columnar frameworks composed of γ-alumina nanocrystalline particles (crystal size of ∼15 nm) and high thermal stability (up to 900 °C). As a support of Au nanoparticles, the formed Au/mesoporous γ-alumina composite catalysts have been used in the catalytic reduction of 4-nitrophenol with a high kinetic constant k of 0.0888 min, implying promising potential as a catalyst support.
Liu Yang Wei Teng Chen Gang Zhao Zaiwang Zhang Wei 孔彪 Hozzein Wael N. Al-Khalaf Areej Abdulkareem 邓勇辉 赵东元
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
Because of its unmatched resource potential, solar energy utilization currently is one of the hottest research areas. Much effort has been devoted to developing advanced materials for converting solar energy into electricity, solar fuels, active chemicals, or heat. Among them, TiO nanomaterials have attracted much attention due to their unique properties such as low cost, nontoxicity, good stability and excellent optical and electrical properties. Great progress has been made, but research opportunities are still present for creating new nanostructured TiO materials. Core-shell structured nanomaterials are of great interest as they provide a platform to integrate multiple components into a functional system, showing improved or new physical and chemical properties, which are unavailable from the isolated components. Consequently, significant effort is underway to design, fabricate and evaluate core-shell structured TiO nanomaterials for solar energy utilization to overcome the remaining challenges, for example, insufficient light absorption and low quantum efficiency. This review strives to provide a comprehensive overview of major advances in the synthesis of core-shell structured TiO nanomaterials for solar energy utilization. This review starts from the general protocols to construct core-shell structured TiO nanomaterials, and then discusses their applications in photocatalysis, water splitting, photocatalytic CO reduction, solar cells and photothermal conversion. Finally, we conclude with an outlook section to offer some insights on the future directions and prospects of core-shell structured TiO nanomaterials and solar energy conversion.
李炜 Elzatahry Ahmed Aldhayan Daifallah M. 赵东元
Chemical Society Reviews
The mesoporous tungsten oxides have shown great potential in various fields, including energy storage and conversion, catalysis, and gas sensor, because they have ordered porous architectures and unique semiconducting property for host–guest interaction. Most of the reported mesoporous tungsten oxides have monomodal mesopores, which are not favorable for the mass diffusion and host–guest interactions. To date, it still remains a great challenge to synthesize ordered mesoporous WO with bimodal or hierarchical pores and crystalline frameworks. Herein, a pore engineering strategy is demonstrated for the synthesis of ordered mesoporous WO with well-connected bimodal pores, and crystalline pore walls by using hydrophilic resols as the sacrificial carbon source which can interact preferentially with poly(ethylene oxide) (PEO) domains and serves a glue to bridge the tungsten species and poly(ethylene oxide)-block-polystyrene block copolymers. The obtained ordered mesoporous tungsten oxide materials possess dual mesopore size (5.8 and 15.8 nm), high surface area (128 m g), large window size (7.7 nm), and highly crystalline mesostructure. The dual mesoporous WO-based gas sensor exhibits significantly excellent gas sensing performance toward HS with a rapid response (3 s) and recovery (14 s) even at low concentration (0.2 ppm), and high selectivity, which is much better than previously reported WO-based sensors.
Yuhui Li Zhou Xinran Wei Luo 程晓维 Zhu Yongheng El-Toni Ahmed Mohamed Khan Aslam 邓勇辉 赵东元
Advanced Materials Interfaces
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
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
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
Functional core-shell mesoporous microspheres with integrated functions, controlled structure, and surface properties and morphologies have received increasing attention due to their excellent physicochemical properties. Herein, core-shell magnetic mesoporous materials with cauliflower-like morphology and tunable surface roughness have been synthesized through a kinetics-controlled interface co-assembly and deposition of mesostructured nanocomposites on FeO@RF microspheres (RF refers to resorcinol formaldehyde resin). The obtained microspheres, synthesized via this interface nanoengineering method, possess well-defined sandwich structure with a tunable rough morphology, uniform size (560-1000 nm), perpendicularly aligned mesopores (∼5.7 nm) in the outer shell, RF-protected magnetic responsive core, high surface area up to 382 m/g, and large pore volume of 0.66 cm/g. As a result of the unique surface features and magnetic properties, these microspheres exhibit excellent performance in stabilizing and oxygen-free manipulating aqueous solutions in petroleum ether by a magnetic field. They also exhibit superior cell uptake properties compared with traditional smooth core-shell magnetic mesoporous silica microspheres, opening up the possible applications in fast drug delivery in cancer therapy.
Qin Yue Yu Zhang Jiang Yongjian Li Jialuo 张宏伟 Chengzhong Yu Elzatahry Ahmed A. Alghamdi Abdulaziz 邓勇辉 赵东元
Journal of the American Chemical Society