Guoying Shi

Morphology-tailored synthesis of vertically aligned 1D WO3 nano-structure films for highly enhanced electrochromic performance

We have demonstrated that vertically aligned WO3 nanostructure films can be fabricated on FTO-coated glass substrates using a template-free hydrothermal technique. Detailed mechanistic studies revealed that a variety of WO3 nanostructures—including nano-bricks, 1D nanorods and nanowires, and 3D nanorod-flowers—could be obtained by tuning the composition of the precursor solution, where the urea content and solvent composition played important roles in controlling the shape and size of the WO3 nanostructures, respectively. These nanostructured films exhibited enhanced electrochromic performance, and we drew a map for the correlation between the morphology and the electrochromic performance of the as-synthesized WO3 films. Due to the large tunnels in the hexagonally structured WO3, and the large active surface area available for electrochemical reactions, a large optical modulation of 66% at 632.8 nm and a potential of −2.0 V, fast switching speeds of 6.7 s and 3.4 s for coloration and bleaching, respectively, and a high coloration efficiency of 106.8 cm2 C−1 are achieved for the cylindrical nanorod array film.

Hierarchical NiO microflake films with high coloration efficiency, cyclic stability and low power consumption for applications in a complementary electrochromic device

We have demonstrated that thin films of hierarchical NiO microflakes assembled from nanoleaves can be grown directly on FTO-coated glass substrates using a facile and template-free hydrothermal technique. This hierarchical structure holds the advantages of both nanometre-sized building blocks and microsized assemblies. Thus, the films exhibit highly enhanced electrochromic performances and cyclic stability due to their high surface area and good electrochemical stability. Moreover, a complementary electrochromic device combining the hierarchical NiO microflake film with a self-weaving WO3 nanoflake film is fabricated to further improve the electrochromic performance. As a result, the complementary electrochromic device shows a high optical modulation (73.2% at 550 nm), large coloration efficiency (146.9 cm(2) C(-1) at 550 nm by applying a low coloration voltage of -1.0 V) and fast switching responses with a coloring time of 1.8 s and a bleaching time of 3.2 s. It is also observed that there is no significant degradation of the electrochromic properties after 2000 continuous coloration/bleaching cycles, making it attractive for practical applications.

Self-seeded growth of nest-like hydrated tungsten trioxide film directly on FTO substrate for highly enhanced electrochromic performance

Self-seeded hydrothermal process could eliminate the grain boundaries existing in the nanocrystalline base layer, which speeds up electron transport to the fluorine-doped tin oxide (FTO) glass and promotes electron transfer efficiency. This report highlights the hierarchical nest-like WO3·0.33H2O film grown directly on bare FTO glass without a seed layer prepared in advance. The film exhibits highly improved electrochromic performances.

Controllable growth of high-quality metal oxide/conducting polymer hierarchical nanoarrays with outstanding electrochromic properties and solar-heat shielding ability

The high performance of organic/inorganic hybrid materials relies largely on a scrupulous design of nanoarchitectures so that the organic and inorganic phases can work synergistically. We present a powerful two-step solution-based method for the fabrication of hierarchical metal oxide/conducting polymer heterostructured nanoarrays. Demonstrated examples include different nanostructures (nanorod arrays, nanorod-based networks and nanoplate arrays) of metal oxides (WO3 and NiO) and PANI (nanostubs, nanoparticles and nano-wrinkles). Given the unique composition and architecture, the hierarchical NiO/PANI nanoplate arrays show reversible multicolor changes, fast switching speeds of 90 and 120 ms for coloration and bleaching states, respectively, and a superior coloration efficiency of 121.6 cm2 C−1 under a low voltage of 1.2 V. Additionally, the application of the NiO/PANI nanoplate array coated FTO glass causes a temperature difference of 7–7.6 °C under different ambient temperatures, making it very attractive for potential applications in energy-saving smart windows. Our strategy paves the way for the design and synthesis of hierarchical metal oxide/conducting polymer nanoarrays with enhanced properties for new applications.

Construction of hydrated tungsten trioxide nanosheet films for efficient electrochromic performance

Tungsten trioxide hydrate (WO3·0.33H2O) films with different morphologies were directly grown on a fluorine doped tin oxide (FTO) substrate. With the directing effect of a seed layer, WO3·0.33H2O thin films composed of nanosheet structures could be selectively synthesized. The effect of urea was also discussed in this paper. The crystal-seed-assisted film grown with urea as a capping agent exhibits efficient electrochromic performances.

Controllable construction of Titanium dioxide-Zirconium dioxide@Zinc hydroxyfluoride networks in micro-capillaries for bio-analysis

Glass/silica-based flow channels are widely used in capillary electrophoresis and micro-total analysis systems. However, it is almost impossible to achieve controllable fabrication of microstructures with enhanced mixing performance for high-efficiency bio-analysis in confined micro-channels. Here, various morphologies were controllably achieved by tuning the molar ratio of the reaction agents in a confined microchannel. Fluid flow simulation is demonstrated to investigate the structure stability and mixing performance. Multifunctional networks with uniform and deep decoration are fabricated in confined micro-capillaries, owing to the enhanced mixing performance. The modified micro-capillaries exhibit high efficiencies for the selective enrichment of phosphopeptides from traditional model samples. Furthermore, the fabricated micro-capillaries also exhibited high performance in practical applications (for selective enrichments from bovine milk and cancer serum). These outstanding features make the microstructure-modified micro-capillaries promising for bio-analysis.

Highly dispersed Co0.5Zn0.5Fe2O4/polypyrrole nanocomposites for cost-effective, high-performance defluoridation using a magnetically controllable microdevice.

Highly dispersed Co(0.5)Zn(0.5)Fe(2)O(4)/polypyrrole (CZFO/PPy) nanocomposites with enhanced electromagnetic properties and large surface area were rapidly and controllably prepared using microfluidic reactors. A novel magnetically controllable microdevice using the new adsorbent in a highly dispersed form was assembled and used for fluoride adsorption. Compared with traditional adsorption methods, the device displayed high adsorption efficiency and capacity. The adsorbents were regenerated with no significant loss in defluoridation ability, which indicates that the device is a realistic and highly efficient alternative way of removing fluoride pollution at low cost.