Youwei Yao

A stimuli-responsive nanogel-based sensitive and selective fluorescent sensor for Cr(3+) with thermo-induced tunable detection sensitivity.

Stimuli-responsive poly(N-isopropylacrylamide) nanogel with covalently labeled rhodamine B urea derivatives (P(NIPAM-co-RhBUA)) is utilized as a sensitive fluorescent probe for Cr(3+) in aqueous solution, and its thermo-induced tunable detection capacity is investigated. At 20 °C, non-fluorescent nanogel can selectively bind with Cr(3+) over some other metal ions, leading to prominent fluorescence OFF-ON switching due to the recognition of RhBUA with Cr(3+) . Upon heating above the phase transition temperature, enhanced fluorescence intensity is observed (≈61-fold increase at 45 °C) for the nanogel in the presence of Cr(3+) , accompanied with an improved detection sensitivity, which suggest that hydrophobic microenvironment generated in the collapsed nanogel plays an active role for their detection performance.

High performance of stretchable carbon nanotube–polypyrrole fiber supercapacitors under dynamic deformation and temperature variation

Flexible fiber-shaped supercapacitors have great potential in wearable electronic devices. Here, we fabricate CNT–PPy composite films by an electrochemical deposition method from macroscopic CNT films. The composite films are transformed into flexible fibers with ultralow density by drawing through several diamond wire-drawing dies. The CNT–PPy fibers have outstanding electrochemical properties with a high specific capacitance of 302 F g−1 in 1 M H2SO4 liquid electrolyte. Flexible, stretchable, all-solid-state, fiber-shaped supercapacitors are then fabricated from the CNT–PPy fibers using H3PO4–poly(vinyl alcohol) as gel electrolyte. The supercapacitor has a high specific capacitance of 69 F g−1, a high power density and an energy density of 3.8 kW kg−1 and 3.6 W h kg−1, respectively. The fiber-shaped supercapacitor also exhibits high stability and reliability under static and dynamic stretching, and also in a wide temperature range from −27 °C to 61 °C.

Cascade OFF–ON–OFF fluorescent probe: dual detection of trivalent ions and phosphate ions

A new rhodamine B-based fluorescent probe was developed for the selective cascade signaling of trivalent cations (Fe3+, Al3+, Cr3+) and phosphate anion (PO43−). Non-fluorescent rhodamine derivatives can selectively detect trivalent cations over some other metal ions in CH3CN–Tris buffer (1/1, v/v, pH 7.0) solutions, leading to prominent fluorescence OFF–ON switching. The obtained probe–cation complex can subsequently serve as a sensitive and selective chemosensor for PO43−, exhibiting complete signal quenching (fluorescence ON–OFF switching).

An easy and accessible water-soluble sensor for the distinctive fluorescence detection of Zn2+ and Al3+ ions

A water-soluble fluorescence sensor (SA) was facilely synthesized via a one-step condensation reaction between commercially available salicylaldehyde and 2-(2-aminoethylamino)ethanol with high yield. The addition of Zn2+ and Al3+ to SA showed drastic enhancements of the emission intensities at 458 nm and 376 nm, respectively, while exhibiting negligible interference in the presence of typical competitive ions such as Fe3+, Cr3+, Hg2+ and Cd2+. This phenomenon indicates that SA may be helpful for rapid, quantitative and qualitative detection of Zn2+ and Al3+.

A novel ratiometric fluorescence sensor for Zn2+ Detection

A novel ratiometric fluorescent sensor for Zn2+, 2-(2-(2-hydroxybenzoyl)hydrazinyl)-N-(quinolin-8-yl)acetamide (F-1) with quinoline as a fluorophore and salicylhydrazide as a receptor, was designed and synthesized. F-1 shows high selectivity and sensitivity for Zn2+ over Cd2+ in a methanol–tris–HCl (0.05 M) buffer solution (1 : 9, v/v, pH = 7.0). Upon the addition of Zn2+, an overall 5-fold increase in the fluorescence emission ratio (I500/I420) was observed. An intermolecular charge transfer (ICT) mechanism is suggested for this ratiometric sensor.

Nonlinear electrical characteristics of core-satellite CaCu3Ti4O12@ZnO doped silicone rubber composites

The application of polymer composites with electric field dependent nonlinear conductive and dielectric characteristics for high voltage equipment is an effective method to control electric field stress and disperse space charges. In this study, core-satellite CaCu3Ti4O12@ZnO fillers were synthesized and doped into silicone rubber composites, and compared to a mixture of CaCu3Ti4O12 and ZnO with the same filler concentration. The composites exhibited both nonlinear conductive and nonlinear dielectric properties with nanoparticle fillers for the first time. Both the nonlinear conductive coefficient and dielectric coefficient increased with filler concentration. The classical current-path model was utilized to explain the nonlinear conductive properties, while the interface-barrier-layer-capacitor model and double-depletion-layer model were introduced to explain the nonlinear dielectric properties, which would broaden the thinking for the fabrication of nonlinear composites.