[en] Translucent TiO₂ nanowires/nanotubes (TiO₂ NW/NT) film would be a promising candidate in constructing photoelectrochemical solar cells for its advantages in sensitizer loading, charge separation, electronic transport and light harvesting. In this report, translucent TiO₂ NW/NT film was prepared by a two-step anodization method. The formation mechanisms of nanowires originated from nanotubes were explored. The hydrogen ions generated by electrolysis of water were driven by electric field to form ions flow, which altered the interfacial stress of nanotubes, resulting in vertically or spirally splitting the mouth of nanotubes to form nanowires. The CdS, CdSe and CdS/CdSe quantum dots (QDs) sensitized TiO₂ NW/NT solar cells were constructed. Among them, The TiO₂ NW/NT solar cells co-sensitized with CdS/CdSe QDs showed higher efficiencies than ones sensitized with CdS or CdSe QDs. By varying successive ionic layer adsorption and reaction (SILAR) cycles of CdS/CdSe, it was found that CdS(9)/CdSe(6)/TiO₂ NW/NT device reached to a maximum power conversion efficiency of 2.41%, which was 78.5% higher than that of the CdS(9)/CdSe(6)/TiO₂ NT solar cell. The excellent photoelectrochemical properties of our solar cell suggest that the translucent TiO₂ NW/NT films co-sensitized with CdS and CdSe QDs have potential application in photovoltaic cells

[en] Highlights: • Translucent TiO_2 nanotubes were used as substrate for QDSSCs. • CdS_xSe_1_-_x/Mn-CdS QDs were sensitized onto TiO_2 nanotubes by a two-stage strategy. • The photoresponse of CdS_xSe_1_-_x/Mn-CdS/TiO_2 nanotubes could be tuned with S/Se. • Extra CdSe layers can improve the power conversion efficiency to 3.26%. • Electrochemical measurements well evidenced the improved photovoltaic performance. - Abstract: Translucent TiO_2 nanotube (NT) array film has been used as supporter materials for the fabrication of CdS_xSe_1_-_x/Mn-CdS quantum dot sensitized solar cell (QDSSC). The TiO_2 NT array electrodes are sensitized with Mn-CdS and CdS_xSe_1_-_x QDs by employing a two-stage sensitization strategy combining successive ionic layer adsorption and reaction (SILAR) techniques and hydrothermal process. The photoresponse region of CdS_xSe_1_-_x/Mn-CdS/TiO_2 NT electrodes could be controlled by the ratio of S and Se. By systematical investigation the optimal composition of CdS_xSe_1_-_x, a high power conversion efficiency of 2.41% is obtained with CdS_0_._4_7Se_0_._5_3/Mn-CdS/TiO_2 NT QDSSC prepared with feed molar ratio of S:Se = 0:4. After being coated with 3 SILAR cycles of CdSe on the CdS_0_._4_7Se_0_._5_3/Mn-CdS/TiO_2 NT electrode, the power conversion efficiency could be further improved to the highest value of 3.26%. The enhancement of power conversion efficiency is mainly attributed to the significant increase of short-circuit current density (J_s_c) which resulted from the improved light harvesting ability caused by expanded light absorption range and efficient electrons collection caused by mid-gap states created by Mn-CdS. These results are well evidenced with the photovoltaic performance studies (J-V behaviors), incident photon to charge carrier generation efficiency (IPCE), and electrochemical impedance spectroscopy (EIS)

[en] A double-layered TiO₂ film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO₂ nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO₂ flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO₂ nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO₂ flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO₂ flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO₂ flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm²), which is 105.7% higher than that of the CdS/TiO₂ nanorod solar cell (0.53%).

[en] Vertically oriented single-crystalline one-dimensional TiO₂ nanorod arrays was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in CdSe/Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The effect of coating cycles of QDs on the photovoltaic performance was investigated to find the optimal combination is 10 cycles of Mn-doped CdS and 9 cycles of CdSe, the CdSe(9)/Mn-CdS(10)/TiO₂ solar cell exhibited the best performance due to the complementary effect in the light absorption of Mn-doped CdS and CdSe QDs. The power conversion efficiency of CdSe(9)/Mn-CdS(10)/TiO₂ solar cell reached to 2.40% under one sun illumination (AM 1.5 G, 100 mW/cm²), which was 46.34% higher than that of CdSe(9)/CdS(10)/TiO₂ solar cell without doping of Mn (1.64%).

[en] Objective: To study the changes of iodine uptake of the follicular thyroid carcinoma cell line (FTC-133) and nude mice bearing human follicular thyroid carcinoma after the induction with all-trans retinoic acid (ATRA), trichostatin A (TSA) or ATRA combined with TSA. Methods: After the induction with ATRA, TSA, or ATRA combined with TSA in different concentrations for 96 h, the iodine uptake of FTC-133 cells was observed. The concentrations for different groups were as follows: ATRA 1.0 ×10^-6 mol/L(A_low group), ATRA 1.0 × 10^-4 mol/L (A_high group), TSA 1.65 ×10^-7 mol/L (T group), A_low + T group, A_high + T group and ethanol (control group). Cell quantities and morphology were observed by HE staining. FTC-133 cells were subcutaneously injected into nude mice. Twelve nude mice were randomly divided into 4 groups after tumor formation: ATRA group (2 mg/kg, intragastric administration), TSA group (10 mg/kg, intraperitoneal injection), combined therapy group (ATRA + TSA, the same doses as above) and saline control group (10 ml/kg, intragastric and intraperitoneal administration, respectively). Drugs were administered to the tumor-bearing mice according to the mouse body mass daily. At the 22nd day, the tumor-bearing mice were injected with 37 MBq ¹³¹I intraperitoneally. The biodistribution of ¹³¹I and gamma imaging were performed at 4, 6, 12 and 24 h after the injection respectively. Histopathological examinations of the tumor samples were taken after imaging completion. The results were analyzed by analysis of variance (ANOVA) with SPSS 13.0. Results: The cellular iodine uptake were (23 885 ± 616.0) and (13 849 ±728.2) counts · min^-1 · 10^-6 cells in the A_low + T group and A_high + T group respectively, and the data were (985 ± 84.2) - (17 600 ± 782.7) counts · min^-1 · 10^-6 in the other groups (F=600.879, P<0.001). The % ID/g of tumor at 6 h was 6.17 ±0.46 in the combined group and it increased to 9.34 ±0.61 at 12 h and 11.19 ± 0.98 at 24 h. The % ID/g of tumor in the other groups were from (1.97 ± 0.34) to (5.14 ± 0.65). The tumor qualities of the 4 groups were significantly different (F=3.723, P<0.05). Conclusion: The iodine uptake of the tumor could be enhanced in the tumor-bearing mice administered with ATRA combined with TSA, a potential way for treating follicular thyroid carcinoma. (authors)

[en] Nanostructured TiO_2 translucent films with different architectures including TiO_2 nanotube (NT), TiO_2 nanowire (NW), and TiO_2 nanowire/nanotube (NW/NT) have been produced by second electrochemical oxidization of TiO_2 NT with diameter around 90–110 nm via modulation of applied voltage. These TiO_2 architectures are sensitized with CdS_xSe_1_−_x alloyed quantum dots (QDs) in sizes of around 3–5 nm aiming to tune the response of the photoelectrochemical properties in the visible region. One-step hydrothermal method facilitates the deposition of CdS_xSe_1_−_x QDs onto TiO_2 films. These CdS_xSe_1_−_x QDs exhibit a tunable range of light absorption with changing the feed molar ratio of S:Se in precursor solution, and inject electrons into TiO_2 films upon excitation with visible light, enabling their application as photosensitizers in sensitized solar cells. Power conversion efficiency (PCE) of 2.00, 1.72, and 1.06 % are achieved with CdS_xSe_1_−_x (obtained with S:Se = 0:4) alloyed QDs sensitized solar cells based on TiO_2 NW/NT, TiO_2 NW, and TiO_2 NT architectures, respectively. The significant enhancement of power conversion efficiency obtained with the CdS_xSe_1_−_x/TiO_2 NW/NT solar cell can be attributed to the extended absorption of light region tuned by CdS_xSe_1_−_x alloyed QDs and enlarged deposition of QDs and efficient electrons transport provided by TiO_2 NW/NT architecture

[en] In this work, the influences of cationic precursors on the quality of photoelectrode, consequently on the performance of the quantum dot-sensitized solar cells (QDSCs) have been studied. CdS QDSCs have been prepared using successive ionic layer absorption and reaction (SILAR) method. Three cadmium precursors including nitrate (Cd(NO_3)_2), chloride (CdCl_2), and acetate (Cd(Ac)_2) were employed for the synthesis and absorption of CdS nanoparticles on nanostructure TiO_2 film. The loading amount and nanoparticle size of the CdS on mesoporous TiO_2 film showed a significant difference while using various cadmium precursors in the same SILAR cycles. Both the light-harvesting ability and the obtained incident photon-to-current conversion efficiency values show the trend of deposition rate caused by cadmium precursors. Further, it was proposed that an effective cationic precursor could provide a good connection between QD sensitizer and TiO_2 interface by electrochemical impedance spectroscopy analysis. Under AM 1.5 G full one sun illumination, the final power conversion efficiency of CdS QDSC based on Cd(Ac)_2 was 2.10 %, and PCE values of 1.57 and 1.20 % were obtained for solar cells sensitized by CdS QDs prepared by CdCl_2 and Cd(NO_3)_2, respectively. The cationic precursor effect was further applied in PbS/CdS co-sensitized solar cells. The PbS/CdS QDSCs based on acetate cationic precursors provide a photocurrent of 19.24 mA/cm"2 and PCE of 3.23 % in comparison with 11.26 mA and 2.13 % obtained with nitrate acetate salts. Noticeably, the CdS and PbS/CdS QDSCs based on various cationic precursors prepared by SILAR exhibited good photocurrent stability under several light on–off cycles

[en] Recently, carbon dots (CDs) have been among the most promising emerging fluorescent labels for cellular imaging. In this work, a new facile synthesis method was developed for fabricating CDs from polystyrene foam waste and common organic solvents. The CDs obtained have tunable emission from blue to orange and are expected to be of use for labeling different cellular structures simultaneously. Transmission electron microscopy, x-ray diffraction, Raman spectra, Fourier transform infrared spectrometry, UV–vis, and fluorescence spectrophotometry (PL) were employed to investigate the structures and luminescence properties of CDs. The highest quantum yield (QY) achieved was 36%. The mechanisms for the formation and luminescence of the CDs are analyzed. The ability of the solvent to disperse the CDs plays a very important role in the origin of PL. The type of organic solvent has an important influence on the position of emission peaks and the QY. Different emissive traps play the dominant role in the luminescence of carbon materials. Furthermore, a hemolysis assay was performed to evaluate the biocompatibility of these CDs in vitro. The biocompatibility of the CDs, even at very high doses, ensures their potential in biomedical applications. (paper)

[en] The M - graphene catalysts (M = Pt, Cu and PtCu; graphene: pristine, Stone - wales, Single - vacancy graphene) for anti - CO poisoning have been learned by the first principles of density functional theory (DFT). For the pure Pt and Cu adsorbed on the graphene, the adsorption capacity of Pt is stronger and the adsorption structure of Pt - graphene is more stable. When Pt is doped by metal Cu, the stability of PtCu catalyst on graphene is stronger than Pt - graphene. By studying the adsorption structures of M - graphene - CO, it has been found that the metal catalysts with the defect graphene as the supporter are better than the pristine graphene in the anti - CO poisoning, and the Cu doped method will improve the tolerance of PtCu catalyst to CO poisoning. Therefore, we can modify the electrode catalyst in the direct methanol fuel cell (DMFC) by doping the non-noble metal Cu in the pure Pt with defect graphene supporter. The catalysts of PtCu - SW and PtCu - SV not only improve their ability to resist CO poisoning and catalysts stability, but also reduce the cost of Pt catalyst in the DMFC. (authors)

[en] Non-metal catalysis of harmful gases maybe the most promising and important way for solving environmental problems. We applied a density functional theory (DFT) to investigate the CO oxidation by using N₂O as an oxidizing agent over a Si-embedded carbon nanotube (Si-CNT) catalyst. The N₂O molecule is more likely to adsorb on the Si-CNT by linear structure, and yield to N₂ and CNT-SiO intermediate with the activation energy of 2.42 kJ/mol. CNT-SiO is an active intermediate which is easy to react with the CO to form CO₂. According to the analysis, the CNT acts as both the electron withdrawing and donating support to assist the charge transfer between the Si atom and the probe molecules. This may open new avenues in searching for oxidation of CO at an economical cost. (authors)