Hongyu Sun

3D anatase TiO2 hollow microspheres assembled with high-energy {001} facets for lithium-ion batteries

3D anatase TiO2 hollow microspheres assembled with high-energy {001} facets have been synthesized by a one-pot solution method and their lithium storage capacity are investigated. The structural and compositional analysis of the mesoporous TiO2 product has been performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) along with selected area electron diffraction (SAED). The Bruauer–Emmett–Teller (BET) specific surface area has been calculated by the nitrogen isotherm curve and pore size distribution of TiO2 microspheres has been determined by the Barret–Joyner–Halenda (BJH) method. It has been found that the as-prepared TiO2 electrodes delivered high capacity, good cycling stability and rate capability. The improved electrochemical performance is attributed to the hollow nature and exposed high-energy {001} facets of the 3D assembled structure. Therefore, such a structure can be considered to be an attractive candidate as an electrode material for LIBs.

Hierarchical CoNiO2 structures assembled from mesoporous nanosheets with tunable porosity and their application as lithium-ion battery electrodes

Mesoporous CoNiO2 hierarchical structures with various specific surface areas and pore size distributions were successfully synthesized by a hydrothermal method and the subsequent annealing process. Structural and compositional analysis indicated that the hierarchical structures were assembled from single-crystal nanosheets. The as-prepared sample when used as an anode material of Li-ion batteries delivered reasonable capacity, good cycling stability and rate capability. It has been found that the specific surface area and the pore nature of CoNiO2 hierarchical structures have a strong influence on their electrochemical performance. The optimal sample delivered a high reversible lithium storage capacity of ∼449.3 mA h g−1 after 50 cycles with high Coulombic efficiency at a current rate of 0.1 A g−1, with good cycling stability and rate capability. It is believed that the improved electrochemical performance can be attributed to the mesoporous nature and the 3D assembled electrode structure. Therefore, such mesoporous hierarchical structures can be considered as attractive candidates as anode materials for LIBs.

Ag-Modified In2O3/ZnO Nanobundles with High Formaldehyde Gas-Sensing Performance

Ag-modified In2O3/ZnO bundles with micro/nano porous structures have been designed and synthesized with by hydrothermal method continuing with dehydration process. Each bundle consists of nanoparticles, where nanogaps of 10–30 nm are present between the nanoparticles, leading to a porous structure. This porous structure brings high surface area and fast gas diffusion, enhancing the gas sensitivity. Consequently, the HCHO gas-sensing performance of the Ag-modified In2O3/ZnO bundles have been tested, with the formaldehyde-detection limit of 100 ppb (parts per billion) and the response and recover times as short as 6 s and 3 s, respectively, at 300 °C and the detection limit of 100 ppb, response time of 12 s and recover times of 6 s at 100 °C. The HCHO sensing detect limitation matches the health standard limitation on the concentration of formaldehyde for indoor air. Moreover, the strategy to synthesize the nanobundles is just two-step heating and easy to scale up. Therefore, the Ag-modified In2O3/ZnO bundles are ready for industrialization and practical applications.