Gaoyi Han

Synthesis and characterization of water-insoluble and water-soluble dibutyltin(IV) porphinate complexes based on the tris(pyridinyl)porphyrin moiety, their anti-tumor activity in vitro and interaction with DNA

The water-insoluble and water-soluble organotin(IV)porphinate complexes based on the tris-(4-pyridinyl)porphyrin and tris(N-methyl-4-pyridiniumyl)porphyrin moieties were synthesized and characterized by elemental analysis, (1)H NMR, IR and electrospray ionization mass spectra. The in vitro activity of the compounds against P388 leukemia and A-549 was determined. The results show that the anti-tumor activities of organotin(IV)porphinate is related to the water solubility of the compounds and the central ion in the porphyrin ring. The interaction between the water-soluble dibutyltin(IV) porphinate (7 and 10) complexes and DNA has been investigated. The result shows that compounds 7 and 10 cause DNA hypochromism measured by A(260), a slight increase in the viscosity of the DNA, and an increase in the melting point of DNA by 2.9 and 1.6 degrees C, respectively at DNA(base)/Drug(Por) ratios of 60. The binding constants to DNA were 1.35+/-0.16 x 10(7) M(-1) (7) and 1.45+/-0.12 x 10(6) M(-1) (10) determined using EB competition method based on the porphyrin concentration, which is 20 and five times greater than that of precursor porphyrins [5-p,o-(carboxy)methoxyphenyl-10,15,20-tris(N-methyl-4-pyridiniumyl)] porphyrin (p,o-tMPyPac) to DNA. Electrophoresis test shows that the compounds cannot cleave the DNA. According to the electrophoresis test result and all the above results, the cytotoxic activity against P388 and A-549 tumor cells appears not to come from the cleavage of DNA caused by the compounds but from the high affinity of compounds to DNA.

High performance of Pt-free dye-sensitized solar cells based on two-step electropolymerized polyaniline counter electrodes

A two-step cyclic voltammetry (CV) approach is employed in a quick and controllable electropolymerization of polyaniline (PANI) nanofibers with a short-branched structure onto fluorinated tin oxide (FTO) glass substrates as counter electrodes (CEs) for Pt-free dye-sensitized solar cells (DSSCs). In the two-step CV method, a small quantity of PANI as a function of the crystal nucleus in the crystal growth, is pre-electropolymerized under a suitably high potential for one cycle at the first-step, then subjected to the second-step for PANI electropolymerization at a low potential for a small number of scans. The well-controlled PANI nanofibers with high performance can be electropolymerized quickly using the two-step mode. The extensive CVs demonstrate the two-step PANI CE has superior electrocatalytic activity for the I3− reduction. Moreover, electrochemical impedance spectroscopy shows that the two-step PANI CE has a lower series resistance and charge-transfer resistance than the PANI CE prepared by conventional one-step CV electropolymerization. Therefore, the DSSC assembled with the two-step PANI CE exhibits an enhanced photovoltaic conversion efficiency of 6.21% (compared to 5.01% for the DSSC with the one-step PANI CE), up to ∼97% of the level of the DSSC using Pt CE. As the result, the two-step CV electropolymerized PANI CE can be considered as a promising alternative CE for Pt-free DSSCs.

Electrospun lead-doped titanium dioxide nanofibers and the in situ preparation of perovskite-sensitized photoanodes for use in high performance perovskite solar cells

Lead-doped TiO2 nanofibers (TNFs) are fabricated by using an electrospun method, followed by the in situ preparation of perovskite-sensitized photoanode for use in perovskite solar cells (PSC). The electrospun TNFs can provide direct pathways for the rapid collection and transmission of photogenerated electrons. The photoanode based on the in situ method shows not only excellent contacting between the TNF and perovskite, but also abundant perovskite filling in it. These can be conducive not only to the separation and transmission of the electron and hole, but also to the absorption and utilization of sunlight. Finally, a high performance PSC with the cell efficiency of 9.03% is obtained without any hole transporting materials.

Preparation of high performance perovskite-sensitized nanoporous titanium dioxide photoanodes by in situ method for use in perovskite solar cells

Perovskite-sensitized nanoporous TiO2 photoanode of several micrometers thickness was prepared for the first time by an in situ technique. The excellent contact between the TiO2 and perovskite could be beneficial to the separation and transmission of the electron and hole while the sufficient filling and abundant CH3NH3PbI3 could enhance the absorption and utilization of sunlight to finally obtain an efficient perovskite solar cell. Note that 10.03% of cell efficiency was achieved without adding hole transporting material into the device.

An Interconnected Ternary MIn2S4 (M=Fe, Co, Ni) Thiospinel Nanosheet Array: A Type of Efficient Platinum‐Free Counter Electrode for Dye‐Sensitized Solar Cells

The ternary iron-group thiospinels of metal diindium sulfides (MIn2 S4 , M=Fe, Co, Ni) with a vertically aligned nanosheet array structure are fabricated through an in situ solvothermal method on F-doped tin oxide (FTO) substrates, which are employed as one type of platinum (Pt)-free counter electrodes (CEs) in structure-dependent dye-sensitized solar cells (DSSCs). A DSSC assembled with ternary CoIn2 S4 CE achieves an photoelectric conversion efficiency (PCE) of 8.83 %, outperforming than that of FeIn2 S4 (7.18 %) and NiIn2 S4 (8.27 %) CEs under full sunlight illumination (100 mW cm-2 , AM 1.5 G), which is also comparable with that of the Pt CE (8.19 %). Putting aside that the interconnected nanosheet array provides fast electron transfer and electrolyte diffusion channels, the highest PCE of CoIn2 S4 based DSSC results from its largest specific surface area (144.07 m2  g-1 ), providing abundant active sites and the largest electron injection efficiency from CE to electrolyte.

An efficient titanium foil based perovskite solar cell: using a titanium dioxide nanowire array anode and transparent poly(3,4-ethylenedioxythiophene) electrode

A titanium (Ti) foil based perovskite solar cell (PSC) is devised and prepared by employing titanium dioxide nanowire (TNW) arrays and titanium dioxide nanoparticles (TNPs) on Ti foil substrates as the electron transporting layer (ETL). The TNW array is desirable for the PSC, since it can provide direct pathways for the rapid collection and transmission of photo-generated electrons. The Ti foil substrate has many advantages such as flexibility, low sheet resistance, and excellent mechanical stability. The sunlight illuminates through the highly transparent poly(3,4-ethylenedioxythiophene) (PEDOT) film on the indium doped tin oxide/polyethylene naphthalate (ITO/PEN) substrate. The transparent PEDOT electrode can be used as the hole transporting layer (HTL) due to the well matched band positions for charge separation and transport. As a result, the Ti foil based light-weight PSC with TNW arrays yields an efficiency of 13.07% with an active area of 1.00 cm2, which is higher than that of the PSC with TNPs (9.93%). These promising results highlight the potential application of the PEDOT and Ti foil in cost-effective, large-area, and flexible PSCs.

Interconnected ternary MIn2S4 (M = Fe, Co, Ni) thiospinels nanosheets array: a type of efficient Pt-free counter electrodes for the dye-sensitized solar cells

The ternary iron group thiospinels of metal diindium sulfides (MIn2S4, M = Fe, Co, Ni) with the vertically aligned nanosheets array structure are fabricated through in situ solvothermal method on F-doped tin oxide substrates, which are employed as one type of platinum (Pt) free counter electrodes (CEs) in the structure-dependent dye-sensitized solar cells (DSSCs). DSSC assembled with ternary CoIn2S4 CE achieves an photoelectric conversion efficiency (PCE) of 8.83%, outperforming than that of FeIn2S4 (7.18%) and NiIn2S4 (8.27%) CEs under full sunlight illumination (100 mW cm−2, AM 1.5 G), which is also comparable with that of Pt CE (8.19%). Putting aside that the interconnected nanosheets array provides fast electron transfer and electrolyte diffusion channels, the highest PCE of CoIn2S4 based DSSC results from its largest specific surface area (144.07 m2 g−1) provides abundant active sites and the largest electron injection efficiency from CE to electrolyte.

Acetylcholinesterase biosensor based on electrochemically inducing 3D graphene oxide network/multi-walled carbon nanotube composites for detection of pesticides

A sensitive electrochemical biosensor for determining organophosphates (OPs) and carbamate pesticides has been achieved by immobilizing acetylcholinesterase (AChE) on electrochemically inducing 3D graphene oxide network/multi-walled carbon nanotube composites (e-GON–MWCNTs). The nanocomposites of e-GON–MWCNTs can provide a favorable environment for the immobilized AChE and improve the electron transfer speed between the analyte and electrode surface. The fabricated AChE biosensors show a favorable affinity to acetylthiocholine chloride (ATCl) with a Michaelis–Menten constant of 0.43 mmol L−1. In the optimal conditions, the biosensor exhibits a linear range of 0.03–0.81 ng mL−1 for detecting carbofuran, and two linear ranges of 0.05–1 ng mL−1 and 1–104 ng mL−1 for detecting paraoxon. Furthermore, the detection limits for carbofuran and paraoxon can reach 0.015 and 0.025 ng mL−1, respectively. The AChE biosensor exhibits good reproducibility and high stability, which demonstrates good efficiency in real sample analysis.

Honeycomb-like polypyrrole/multi-wall carbon nanotube films as an effective counter electrode in bifacial dye-sensitized solar cells

AbstractHoneycomb-like polypyrrole/multi-wall carbon nanotube (PPy/MWCNT) film demonstrates as an efficient and semitransparent counter electrode (CE) in bifacial dye-sensitized solar cell (DSSC), which is first fabricated on fluorine-doped tin oxide glass by a facile method using a sacrificial template of poly(methyl methacrylate) (PMMA). The results from ultraviolet–visible spectrophotometer and cyclic voltammetry measurements testify that the honeycomb-like PPy/MWCNT film possesses high transparency for the backside illumination and wonderful electrocatalytic activity for the reduction of triiodide (I3−) to iodide (I−) in the bifacial DSSC. Electrochemical impedance spectroscopy results indicate that the honeycomb-like nanostructure combining with the MWCNT decreases the resistance of the PPy/MWCNT film for the transfer of electrons from the external circuit back to the redox electrolyte. The bifacial DSSC based on the honeycomb-like PPy/MWCNT CE achieves 7.07 and 4.11% of the front and rear efficiencies, respectively, which are higher than those of the bifacial DSSC based on the flat PPy CE (5.78 and 3.07%, respectively).

Phenanthroimidazole derivatives as emitters for non-doped deep-blue organic light emitting devices

A series of phenanthroimidazole derivatives with N-1 and C-2 position modification have been synthesized, characterized and applied as non-doped emitters in organic light-emitting devices (OLEDs). The compounds show high fluorescence quantum yields high up to 87.51% in solid powder state as well as good thermal and film-forming properties. Crystal structures of 2N-PI, 1N-BPI and 2N-API were determined by X-ray crystallography. Correlations between optoelectronic properties, energy levels and molecular structures of the materials were investigated. It was found that the fluorescence properties of the materials were related to the dihedral angles and moiety replacement position. N-1-imidazole modification (e.g.: 2N-API) favours deep-blue emission, although with a relatively lower quantum yield, it shows comparable device efficiency towards the C-2-imidazole derivative (e.g.: 2N-BPI).