Quan Jin

Accurate Control of Multishelled Co3O4 Hollow Microspheres as High-Performance Anode Materials in Lithium-Ion Batteries

More than just an empty shell: Multishelled Co3O4 microspheres were synthesized as anode materials for lithium-ion batteries in high yield and purity. As their porous hollow multishell structure guarantees a shorter Li+ diffusion length and sufficient void space to buffer the volume expansion, their rate capacity, cycling performance, and specific capacity were excellent (1615.8 mA?h?g-1 in the 30th cycle for triple-shelled Co3O4; see graph).

α-Fe2O3 multi-shelled hollow microspheres for lithium ion battery anodes with superior capacity and charge retention

Multi-shelled α-Fe2O3 hollow microspheres were synthesized using carbonaceous microsphere sacrificial templates and utilized for high capacity anode materials in lithium ion batteries (LIBs). Structural aspects including the shell thickness, number of internal multi-shells, and shell porosity were controlled by synthesis parameters to produce hollow microspheres with maximum lithium capacity and stable cycling behavior. Thin, porous, hollow microspheres with three concentric multi-shells showed the best cycling performance, demonstrating excellent stability and a reversible capacity of up to 1702 mA h g−1 at a current density of 50 mA g−1. The electrode performance is attributed to the large specific surface area and enhanced volumetric capacity of the multi-shelled hollow spheres that provide maximum lithium storage, while the porous thin shells facilitate rapid electrochemical kinetics and buffer mechanical stresses that accompany volume changes during de/lithiation.

Multishelled TiO2 hollow microspheres as anodes with superior reversible capacity for lithium ion batteries

Herein, uniform multishelled TiO2 hollow microspheres were synthesized, especially 3- and 4-shelled TiO2 hollow microspheres were synthesized for the first time by a simple sacrificial method capable of controlling the shell thickness, intershell spacing, and number of internal multishells, which are achieved by controlling the size, charge, and diffusion rate of the titanium coordination ions as well as the calcination process. Used as anodes for lithium ion batteries, the multishelled TiO2 hollow microspheres show excellent rate capacity, good cycling performance, and high specific capacity. A superior capacity, up to 237 mAh/g with minimal irreversible capacity after 100 cycles is achieved at a current rate of 1 C (167.5 mA/g), and a capacity of 119 mAh/g is achieved at a current rate of 10 C even after 1200 cycles.

Quintuple-Shelled SnO2 Hollow Microspheres with Superior Light Scattering for High-Performance Dye-Sensitized Solar Cells

Quintuple-shelled SnO2 hollow microspheres are prepared by a hard-template method. DSSCs constructed with SnO2 multi-shell photoanodes show a record photoconversion efficiency of 7.18% due to enhanced light scattering. SnO2 hollow microspheres that are utilized as a scattering layer on top of P25 films increase the DSSC photoconversion efficiency from 7.29% to 9.53%.

Multi-shelled metal oxides prepared via an anion-adsorption mechanism for lithium-ion batteries

One of the major problems in the development of lithium-ion batteries is the relatively low capacity of cathode materials compared to anode materials. Owing to its high theoretical capacity, vanadium oxide is widely considered as an attractive cathode candidate. However, the main hindrances for its application in batteries are its poor capacity retention and low rate capability. Here, we report the development of multi-shelled vanadium oxide hollow microspheres and their related electrochemical properties. In contrast to the conventional cation-adsorption process, in which the metal cations adsorb on negatively charged carbonaceous templates, our approach enables the adsorption of metal anions. We demonstrate controlled syntheses of several multi-shelled metal oxide hollow microspheres. In particular, the multi-shelled vanadium oxide hollow microspheres deliver a specific capacity of 447.9 and 402.4mAhg(-1) for the first and 100th cycle at 1,000mAg(-1), respectively. The significant performance improvement offers the potential to reduce the wide capacity gap often seen between the cathode and anode materials.

Dually Ordered Porous TiO2-rGO Composites with Controllable Light Absorption Properties for Efficient Solar Energy Conversion

Quadruple-layered TiO2 films with controllable macropore size are prepared via a confinement self-assembly method. The inverse opal structure with ordered mesoporous (IOM) presents unique light reflection and scattering ability with different wavelengths. Cyan light (400-600 nm) is reflected and scattered by IOM-195, which is in accord with N719 absorption spectra. By manipulating the macropore size, different light responses are obtained.

Few‐Layer Graphdiyne Nanosheets Applied for Multiplexed Real‐Time DNA Detection

Despite recent progress in 2D nanomaterials-based biosensing, it remains challenging to achieve sensitive and high selective detection. This study develops few-layer graphdiyne (GD) nanosheets (NSs) that are used as novel sensing platforms for a variety of fluorophores real-time detection of DNA with low background and high signal-to-noise ratio, which show a distinguished fluorescence quenching ability and different affinities toward single-stranded DNA and double-stranded DNA. Importantly, for the first time, a few-layer GD NSs-based multiplexed DNA sensor is developed.

Synthesis and photocatalytic activity of hierarchical flower-like SrTiO3 nanostructure

A hierarchical flower-like SrTiO3 nanostructure was synthesized by a simple and direct hydrothermal method. The products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Structure characterizations suggest that the as-synthesized SrTiO3 crystal has eight symmetric branches growing along the 〈111〉 direction and each branch has many ordered small laminae, forming a well-defined flower-like structure. By adjusting the pH value of the reaction system, the morphology could be changed continuously from flower-like structure to cube, then to sphere. The hierarchical flower-like SrTiO3 nanostructure exhibits a higher photocatalytic activity for degrading Rhodamine B than its cubic and spherical counterparts.摘要本文报道了一种钛酸锶花状分级纳米结构. 实验结果表明该钛酸锶花状分级纳米结构沿钛酸锶晶体的〈111〉方向生长, 形成八个分枝结构, 每个分枝结构由一系列纳米片堆叠而成, 整个粒子具有花状的形貌结构. 通过调节反应体系的pH值, 可以得到纳米立方、 纳米球等其它形貌结构的钛酸锶晶体. 所合成钛酸锶对光催化降解罗丹明B染料具有较高活性, 其中花状分级纳米结构钛酸锶的光催化活性显著高于其它两种结构, 在光催化领域具有潜在应用前景.

Synthesis of a hierarchically meso-macroporous TiO2 film based on UV light-induced in situ polymerization: application to dye-sensitized solar cells

Hierarchically meso-macroporous TiO2 films were prepared via a UV light-induced in situ polymerization of hybrid organic–inorganic films containing propoxylated glyceryltriacrylate monomers and titania precursors. These films were composed of well-connected, net-like frameworks with a large open cavity (0.2–1.5 μm), which were assembled by titania nanocrystals with a size of ∼25 nm and that possessed relatively rich inner crystal mesopores of about 4 nm. The particular net-like frameworks make the film a promising candidate for use as the scattering layer in dye-sensitized solar cells (DSSCs). A bilayer structured photo-electrode, consisting of the net-like framework layer on top of the P25 film, was prepared and exhibited good overall conversion efficiency. Interestingly, the photovoltaic conversion efficiency (η) was improved to 6.95%, much higher than that of P25 single-layer film (6.17%).

Catalytic cracking of 1, 3, 5-triisopropylbenzene over silicoaluminophosphate with hierarchical pore structure

In order to prepare a highly active catalyst for the catalytic cracking of larger molecules, a novel micro-mesoporous silicoaluminophosphate composite (define as mesoporous SAPO-5) with hierarchical tri-modal pore size distributions has been firstly synthesized via post-synthetic method in acidic condition and subsequently characterized. Morphology control of the composite is attempted by adjusting pH value of the synthetic system. Three different morphologies of composite, including sphere-, rod- and net-like, are obtained in the different conditions. Possible mechanism for the formation of mesoporous SAPO-5 has been proposed. The mesoporous SAPO-5 exhibits higher cracking activity than conventional microporous SAPO-5 for cracking of 1, 3, 5-triisopropylbenzene (1, 3, 5-TIPB) under the same reaction conditions. The result indicates that the mesoporous SAPO-5 with hierarchical pore structure is favorable for catalytic cracking of large molecule. When the cumene as the reaction molecule, the microporous SAPO-5 catalyst exhibits higher conversion in catalytic cracking of cumene compared to the mesoporous SAPO-5, and the result may be attributed to that microporous SAPO-5 has much stronger acidity and specific selectivity than mesoporous SAPO-5 catalyst in catalytic cracking of cumene. Meanwhile, corresponding carbenium ion mechanism can account for the products formed during the whole reaction process.