Xiaoyu Hou

In Situ Deposition of Hierarchical Architecture Assembly from Sn-Filled CNTs for Lithium-Ion Batteries

In this paper, we have demonstrated a hierarchical architecture assembly from Sn-filled CNTs, which was in situ deposited on Cu foils to form binder-free electrode by incorporating flame aerosol deposition (FAD) with chemical vapor deposition (CVD) processes. The reversible capacity of Sn-filled CNTs hierarchical architecture anode exhibited above 1000 mA h g(-1) before 30th cycle and stabilized at 437 mA h g(-1) after 100 cycles at a current density of 100 mA g(-1). Even at as high as 2 A g(-1), the capacity still maintained 429 mA h g(-1). The desirable cycling life and rate capacities performance were attributed to great confinement of tin in the interior of CNTs and the superior conducting network constructed by the 3D hierarchical architecture. The novel, rapid and scalable synthetic route was designed to prepare binder-free electrode with high electrochemical performance and avoid long-time mixing of active materials, binder, and carbon black, which is expected to be one of promising preparation of Sn/C anodes in lithium-ion batteries.

One-step synthesis of SnOx nanocrystalline aggregates encapsulated by amorphous TiO2 as an anode in Li-ion battery

SnOx nanocrystalline aggregates (NAs) encapsulated by an amorphous TiO2 layer have been successfully designed by a one-step flame spray pyrolysis (FSP). The synthesized SnOx NAs@TiO2 with different degrees of aggregations were composed of SnOx nanocrystallites ranging from 5 nm to 10 nm and a TiO2 layer with a thickness of 1–5 nm. The encapsulated TiO2 layer was introduced in situ by incorporating TiCl4 into the downstream of an FSP reactor, where TiO2 nucleated and grew in the surface of the SnOx NAs. The hydrolysis temperature of TiCl4 in a flame was controlled to synthesize amorphous TiO2 with intrinsic electrochemical features. As an anode in LIBs (Li-ion batteries), the SnOx NAs@TiO2 electrode showed superior cycle life and rate performance (capacity of 350 mA h g−1 after 300 cycles and 332 mA h g−1 at 1 A g−1) compared to pure SnOx or TiO2 electrodes. The remarkably enhanced Li+ storage performance is mainly attributed to the nanoscale of nanocrystalline aggregates, the core–shell structure of SnOx@TiO2 and the amorphous state of TiO2.

Phase-segregation induced growth of core–shell α-Fe2O3/SnO2 heterostructures for lithium-ion battery

In this paper, novel core–shell α-Fe2O3/SnO2 heterostructures (HSs) are successfully prepared by a one-step flame-assisted spray copyrolysis of iron and tin precursor. The effect of SnO2 component is investigated for the evolution of phase composition and morphology in detail. For the first time, it is noted that SnO2 as a dopant can effectively promote the phase transition of γ-Fe2O3 to α-Fe2O3 during flame synthesis. A phase-segregation induced growth mechanism is proposed to explain the formation of a unique core–shell structure. Such core–shell HSs as LIB anode materials exhibit an enhanced lithium storage capacity in comparison to pure Fe2O3 and SnO2. This enhancement could be ascribed to the synergetic effect of both single components as well as the unique core–shell HSs.

Aerosol construction of multi-shelled LiMn2O4 hollow microspheres as a cathode in lithium ion batteries

Advanced cathode materials with optimal balanced pore structures and tap densities have attracted much attention for use the of next generation lithium ion batteries (LIBs). Herein, multi-shelled LiMn2O4 hollow microspheres (named ms-LMO HMs) have been successfully prepared by a facile aerosol spray pyrolysis route through the controlled combustion of carbon species. The obtained microspheres, with diameters of 0.5–2 μm, are assembled from nanosized LiMn2O4 particles (10–30 nm) and exhibit intriguing hollow structures with multishells. When used as cathode materials in LIBs, ms-LMO HMs show a superior specific capacity of 110 mA h g−1 with 400 cycles at 0.2 A g−1, as well as a good rate capacity. This is mainly owing to the multilevel voids, porous internal/external shells and nanosized particles for facile wetting of the electrode and electrolyte and a facilitated Li+ ion diffusion pathway.

Highly compressible magnetic liquid marbles assembled from hydrophobic magnetic chain-like nanoparticles

We demonstrated a large-scale, low-cost and rapid flame synthesis of hydrophobic magnetic chain-like nanoparticles (HMCNPs) composed of core–shell Fe2O3@SiO2 nanoparticles. The liquid marble made up of HMCNPs is highly compressible with rapid self-recovering ability mainly due to the intriguing elastic behavior and magnetic performance.

Construction of core–shell Fe2O3@SnO2 nanohybrids for gas sensors by a simple flame-assisted spray process

In this paper, core–shell Fe2O3@SnO2 nanohybrids were fabricated via a simple flame-assisted spray pyrolysis (FASP) process. A shell layer composed of SnO2 nanocrystals (8–10 nm) was grown in situ on the pristine Fe2O3 nanoparticles, with a tailored thickness ranging from 6–20 nm. The construction of such an intriguing structure thus provided a rational and efficient combination of two kinds of gas sensitive materials, resulting in a remarkably enhanced sensing ability (Ra/Rg) and good selectivity in the detection of 22.8 to 100 ppm ethanol vapor at 300 °C, compared to the corresponding pure Fe2O3 and SnO2 materials synthesized by FASP. This enhancement can be mainly attributed to the synergistic effects arising from the presence of both of these materials, i.e. the change of the heterojunction barrier height at the Fe2O3/SnO2 interface. In addition, the in situ flame coating process provides a promising and versatile choice for the synthesis of core–shell nanostructures with multifunctional compositions.

In situ Au-catalyzed fabrication of branch-type SnO2 nanowires by a continuous gas-phase route for dye-sensitized solar cells

Branch-type SnO2 nanowires with high crystallinity have been successfully prepared by a rapid and continuous flame spray pyrolysis (FSP) route. The SnO2 branch has an average diameter of 15–20 nm and a length of 200–700 nm. As is known, this is the first time one dimensional SnO2 nanowires with branch-type nanostructures have been synthesized using flame synthesis. The average growth rate of nanowires could reach 1 μm s−1, which is thousand times faster than other methods. Interestingly, it is found that Au nanoclusters appear at the tip of SnO2 nanowires. An in situ Au-catalyzed vapour–liquid–solid (VLS) model is proposed to explain the growth mechanism of branch-type SnO2 nanowires in flame. As photoanodes, the DSSCs based on branch-type SnO2 nanowires (with TiCl4 post-treatment) show a higher short-circuit current (JSC = 10.60 mA cm−2) and a superior power conversion efficiency of 4.23%, improved by 99.5% compared to pure SnO2 nanoparticles (2.12%). The efficiency improvement could be attributed to the unique branch-type nanowire architecture, which provides a highly efficient electron channel and excellent ability of light scattering.