Sujian You

Highly Transparent Carbon Counter Electrode Prepared via an in Situ Carbonization Method for Bifacial Dye-Sensitized Solar Cells

A facile in situ carbonization method was demonstrated to prepare the highly transparent carbon counter electrode (CE) with good mechanical stability for bifacial dye-sensitized solar cells (DSCs). The optical and electrochemical properties of carbon CEs were dramatically affected by the composition and concentration of the precursor. The well-optimized carbon CE exhibited high transparency and sufficient catalytic activity for I3(-) reduction. The bifacial DSC with obtained carbon CE achieved a high power conversion efficiency (PCE) of 5.04% under rear-side illumination, which approaches 85% that of front-side illumination (6.07%). Moreover, the device shows excellent stability as confirmed by the aging test. These promising results reveal the enormous potential of this transparent carbon CE in scaling up and commercialization of low cost and effective bifacial DSCs.

Capture and release of cancer cells using electrospun etchable MnO2 nanofibers integrated in microchannels

This paper introduces a cancer cell capture/release microchip based on the self-sacrificed MnO2 nanofibers. Through electrospinning, lift-off and soft-lithography procedures, MnO2 nanofibers are tactfully fabricated in microchannels to implement enrichment and release of cancer cells in liquid samples. The MnO2 nanofiber net which mimics the extra cellular matrix can lead to high capture ability with the help of a cancer cell-specific antibody bio-conjugation. Subsequently, an effective and friendly release method is carried out by using low concentration of oxalic acid to dissolve the MnO2 nanofiber substrate while keeping high viability of those released cancer cells at the same time. It is conceivable that our microchip may have potentials in realizing biomedical analysis of circulating tumor cells for biological and clinical researches in oncology.

Highly sensitive microfluidic flow sensor based on aligned piezoelectric poly(vinylidene fluoride-trifluoroethylene) nanofibers

A microfluidic flow sensor based on aligned piezoelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] nanofibers has been developed. The flow sensor is able to linearly measure low flow rates ranging from 13 μl/h to 301 μl/h with a sensitivity of 0.36 mV per 1 μl/h, and the highest voltage difference of 120 mV at a flow rate of 451 μl/h. Moreover, the viscosity of the ethylene glycol aqueous solution ranging from 1 mPa·s to 16.1 mPa·s at 25 °C can be detected in dynamic flow with a stable output. These findings highlight the potential of piezoelectric P(VDF-TrFE) nanofibers in multiferroic applications.

Self-amplified piezoelectric nanogenerator with enhanced output performance: The synergistic effect of micropatterned polymer film and interweaved silver nanowires

A piezoelectric nanogenerator with self-amplified output is prepared with a polydimethylsiloxane (PDMS)/silver nanowire (Ag NW)/poly(vinylidene fluoride-trifluoroethylene) sandwich structure. The Ag NWs facilitate the collection of induced charge generated by the piezoelectric film, and the micro-patterned PDMS films multiply the devices sensitivity under external compression. The nanogenerator exhibits good performance, with a peak open circuit voltage of 1.2 V, and a peak short circuit current of 82 nA. These findings highlight the potential of the nanogenerator in self-powered devices and wearable energy harvesters.

Microfluidic synthesis of multiferroic Janus particles with disk-like compartments

Aiming to synthesize multiferroic materials in microscale, a microfluidic device capable of generating multiferroic Janus microparticles is demonstrated. Through bonding two polydimethylsiloxane (PDMS) layers “face to face,” laminar flow containing an upper layer and a lower layer can be realized. Accordingly, poly(vinylidene fluoride-trifluoroethylene) ferroelectric polymers and Fe3O4 ferromagnetic particles are separately encapsulated in the two layers of a single droplet. Numerical simulation enables the analysis of cross-mixing between the two counterparts and helps to find an optimized location for adding subsequent ultraviolet treatment, which will polymerize the droplets into Janus particles without any side effect. By modulation of the flow rate, the size of the Janus particles can be precisely tuned. Finally, the ferroelectricity and magnetism of the Janus particles are verified by the magnetization and polarization measurements, indicating the multiferroic nature.

Efficient dye-sensitized solar cells employing highly environmentally-friendly ubiquinone 10 based I2-free electrolyte inspired by photosynthesis

A highly environmentally-friendly ubiquinone 10 (UQ10) based I2-free electrolyte, which is inspired by photosynthesis, is employed in dye-sensitized solar cells (DSSCs) under 100 mW cm−2 (AM 1.5G) illumination. Profiting from this UQ10 based electrolyte a 10% increased power conversion efficiency of 8.18% is achieved compared with the traditional one containing I2 (7.44%). The superior performance of this UQ10 based electrolyte is mainly derived from the lower visible light wastage and high catalytic activity to the counter electrode as revealed by photoelectrochemical characterization. Moreover, being widely adopted in cardiovascular medicine and cosmetics, UQ10 is a very safe and low-cost choice for DSSCs. With the advantages of high power conversion efficiency, bio-safety, universal dye compatibility and diversity of molecular design, UQ10 is very promising to be widely applied in DSSCs, and perovskite based solar cells.

Generation of BiFeO3-Fe3O4 Janus particles based on droplet microfluidic method

We report on the feasible generation of BiFeO3-Fe3O4 Janus particles (JPs) based on droplet microfluidic method. Utilizing laminar flow and flow-focusing in microchannels, BiFeO3 and Fe3O4 nanoparticles were separately embedded in each hemisphere of one hydrogel particle. The size of the Janus particles showed favorable uniformity at micron scale and could be precisely controlled by flow rate regulation. The magnetism and ferroelectricity of the JPs were confirmed by magnetization and polarization measurements, indicating potential in multiferroic applications.

A Concentration-Controllable Microfluidic Droplet Mixer for Mercury Ion Detection

A microfluidic droplet mixer is developed for rapid detection of Hg(II) ions. Reagent concentration and droplets can be precisely controlled by adjusting the flow rates of different fluid phases. By selecting suitable flow rates of the oil phase, probe phase and sample phase, probe droplets and sample droplets can be matched and merged in pairs and subsequently well-mixed in the poly (dimethylsiloxane) (PDMS) channels. The fluorescence enhancement probe (Rhodamine B mixed with gold nanoparticles) encapsulated in droplets can react with Hg(II) ions. The Hg(II) ion concentration in the sample droplets is adjusted from about 0 to 1000 nM through fluid regulation to simulate possible various contaminative water samples. The intensity of the emission fluorescence is sensitive to Hg(II) ions (increases as the Hg(II) ion concentration increases). Through the analysis of the acquired fluorescence images, the concentration of Hg(II) ions can be precisely detected. With the advantages of less time, cost consumption and easier manipulations, this device would have a great potential in micro-scale sample assays and real-time chemical reaction studies.