Bolei Chen

In situ prepared transparent polyaniline electrode and its application in bifacial dye-sensitized solar cells.

Highly uniform and transparent polyaniline (PANI) electrodes that can be used as counter electrodes in dye-sensitized solar cells (DSSCs) were prepared by a facile in situ polymerization method. They were used to fabricate a novel bifacially active transparent DSSC, which showed conversion efficiencies of 6.54 and 4.26% corresponding to front- and rear-side illumination, respectively. Meanwhile, the efficiency of the same photoanode employing a Pt counter electrode was 6.69%. Compared to conventional Pt-based DSSCs, the design of the bifacial DSSC fabricated in this work would help to bring down the cost of energy production due to the lower cost of the materials and the higher power-generating efficiency of such devices for their capabilities of utilizing the light from both sides. These promising results highlight the potential application of PANI in cost-effective, transparent DSSCs.

One-pot synthesis of three-dimensional silver-embedded porous silicon micronparticles for lithium-ion batteries

Three-dimensional silver-embedded porous silicon (3D Ag@porous silicon) micronparticles were synthesized by a facile and low cost method via a metal-assisted chemical etching process for the first time. The electrode based on this 3D Ag@porous silicon anode material reveals a significant improvement in the electrochemical performance that results from its unique interconnected 3D network structure and the existence of high conductive silver nanoparticles encapsulated in the matrix of porous silicon. The battery based on 3D Ag@porous silicon micronparticles still retains a discharge capacity of 784 mA h g−1 after 50 cycles, which is more than two times larger compared with that of graphite (∼372 mA h g−1). These results suggest that this facile and low cost methodology for preparation of a porous silicon anode can be extended to industrial production.

Morphology-Controlled Synthesis of Self-Assembled LiFePO4/C/RGO for High-Performance Li-Ion Batteries

Novel architectured LiFePO4 (LFP) that consisted of ordered LFP nanocubes was prepared through a facile hydrothermal method using polyethylene glycol (PEG) as a surfactant. The micro/nanostructured LFP with various morphologies ranging from cube cluster to rugby-like structure was synthesized via controlling the pH values of the precursor. A reasonable assembly process elucidating the formation of the hierarchical structure is also provided based on the experimental results. After a combination of carbon (C) coating and reduced graphene oxide (RGO) wrapping, the obtained LFP/C/RGO composites exhibit enhanced electrochemical performance compared to that of blank LFP synthesized under the same condition. Among as-synthesized cube-cluster-like, dumbbell-like, rod-like, and rugby-like composites, the rugby-like LFP/C/RGO reveal the best electrochemical properties with the discharge specific capacity of ∼150 mA h g(-1) after 100 cycles and a high reversible specific capacity of 152 mA h g(-1) at 0.1 C. The prepared LFP/C/RGO composite can be a promising cathode material for high energy, low cost, and environmentally friendly lithium-ion batteries.

Capture and Release of Cancer Cells Based on Sacrificeable Transparent MnO2 Nanospheres Thin Film

A CTCs detection assay using transparent MnO2 nanospheres thin films to capture and release of CTCs is reported. The enhanced local topography interaction between extracellular matrix scaffolds and the antibody-coated substrate leads to improved capture efficiency. CTCs captured from artificial blood sample can be cultured and released, represent a new functional material capable of CTCs isolation and culture for subsequent studies.

Optimization of a quasi-solid-state dye-sensitized solar cell employing a nanocrystal?polymer composite electrolyte modified with water and ethanol

A quasi-solid-state dye-sensitized solar cell employing a poly(ethylene oxide)-poly(vinylidene fluoride) (PEO-PVDF)/TiO2 gel electrolyte modified by various concentrations of water and ethanol is described. It is shown that the introduction of water and ethanol prevents the crystallization of the polymer matrix, and enhances the free I(-)/I(3)(-) concentration and the networks for ion transportation in the electrolyte, thus leading to an improvement in conductivity. A high energy conversion efficiency of about 5.8% is achieved by controlling the additive concentration in the electrolyte. Optimization of the additive-modified electrolyte performance has been obtained by studying the cross-linking behavior of water and ethanol with Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and viscosity measurements, and the electrical conduction behavior of the electrolyte with impedance spectra measurements.

Three-Dimensional Branched TiO2 Architectures in Controllable Bloom for Advanced Lithium-Ion Batteries

Three-dimensional branched TiO2 architectures (3D BTA) with controllable morphologies were synthesized via a facile template-free one-pot solvothermal route. The volume ratio of deionized water (DI water) and diethylene glycol in solvothermal process is key to the formation of 3D BTA assembled by nanowire-coated TiO2 dendrites, which combines the advantages of 3D hierarchical structure and 1D nanoscale building blocks. Benefiting from such unique structural features, the BTA in full bloom achieved significantly increased specific surface areas and shortened Li(+) ion/electrons diffusion pathway. The lithium-ion batteries based on BTA in full bloom exhibited remarkably enhanced reversible specific capacity and rate performance, attributing to the high contact area with the electrolyte and the short solid state diffusion pathway for Li(+) ion/electrons promoting lithium insertion and extraction.

Effect of thickness on structural, electrical, and electrochemical properties of platinum/titanium bilayer counterelectrode

To strengthen the adhesion of platinum layer to counterelectrodes of dye sensitized solar cells, titanium thin film has been utilized as adhesion layer between platinum and substrate [Wei et al., Appl. Phys. Lett. 90, 153122 (2007)]. In our study, platinum/titanium bilayer counterelectrodes were fabricated by magnetron sputtering. The structural, electrical, and electrochemical properties of the bilayer counterelectrode were studied by varying the thickness of both platinum and titanium layers. The influence of both electrochemical active surface and crystallite size on charge transfer resistance of the bilayer counterelectrode was explored. From these evaluations, it was found that the as-prepared titanium layer was almost amorphous, and intermetallic phase was formed between platinum and titanium layers. As expected, sheet resistance of the electrode decreased with the increase in deposition time of both platinum and titanium layers. Metal titanium was found to be inert in the catalyzing reduction in tr...

Facile preparation of nanofibrous polyaniline thin film as counter electrodes for dye sensitized solar cells

A fibrous polyaniline (PANI) thin film has been fabricated from prepared PANI nanofiber solution by Marangoni flow. The PANI retained its original fiber morphology after being deposited into films and formed highly interconnected network structures, which leads to an excellent electrochemical catalytic activity. This PANI thin film was applied in dye sensitized solar cell (DSSC) as counter electrode. A power conversion efficiency (PCE) of 3.8% of the DSSC by this PANI counter electrode was obtained without optimization of synthesis conditions, compared with 5.1% PCE by traditional Pt counter electrode. Better performances are attainable by improving the conductivity of PANI with acid doping process to decrease the sheet resistance of this electrode. Facile synthesis process and good performance of these nanofibrous PANI thin films highlight the potential large scale applications for low-cost counter electrode in DSSCs.

A methylene bridged bisimidazolium iodide based low-volatility electrolyte for efficient dye-sensitized solar cells

In this paper, we demonstrate that 1,1′-methylene bis(3-n-methylimidazolium) diiodide (MMIDI) can be used as an excellent alternative iodide source to conventional lithium iodide (LiI) in electrolyte for dye-sensitized solar cell (DSSC). The MMIDI is cheaper and shows much improved physical and chemical stability compared to LiI. Noticeably, smaller charge transfer resistance for the reduction of triiodide and longer electron lifetime are found in the DSSCs based on MMIDI electrolyte, which result in a 23% higher overall conversion efficiency (5.26%) than that based on LiI electrolyte (4.27%). When the initial MMIDI electrolyte is optimized with functional additives, a promising 6.24% conversion efficiency is achieved.