Wu Jihuai

Efficiency improvement of flexible dye-sensitized solar cells by introducing mesoporous TiO 2 microsphere

Mesoporous TiO2 microsphere (MTM) was synthesized via a simple solution route and then mixed with commercial TiO2 (P25) to form highly homogeneous and stable TiO2 colloid by simple hydrothermal treatment. The TiO2 colloid was coated onto the plastic conductive substrate to prepare mesoporous TiO2 film for flexible dye-sensitized solar cells (DSSCs) by low-temperature heat treatment. The influence of MTM content on the physicochemical properties of the flexible TiO2 film was characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectrometer, N2 adsorption-desorption isotherms, UV-vis absorption and diffuse reflectance spectra. It is revealed that with increasing the MTM content, the dye-loading capability of TiO2 film and light-harvesting efficiency of flexible DSSCs are improved due to MTM having high surface area and acting as a light scattering center, respectively, resulting in the enhancement of photocurrent of flexible DSSCs. However, more and larger cracks having negative effect on the performances of flexible DSSCs are formed simultaneously. Under the optimal condition with MTM content of 20%, a flexible DSSC with overall light-to-electric energy conversion efficiency of 2.74% is achieved under a simulated solar light irradiation of 100 mW cm−2 (AM 1.5), with 26% improvement in comparison with DSSCs based on P25 alone.

Solvothermal synthesis of Bi2O3/BiVO4 heterojunction with enhanced visible-light photocatalytic performances*

Novel, three-dimensional, flower-like Bi2O3/BiVO4 heterojunction photocatalysts have been prepared by the combination of homogeneous precipitation and two-step solvothermal method followed by thermal solution of NaOH etching process. The as-obtained samples were fully characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Brunauer-Emmett-Teller surface area, and UV—vis diffuse-reflectance spectroscopy in detail. The crystallinity, microstructure, specific surface area, optical property and photocatalytic activity of samples greatly changed depending on solvothermal reaction time. The photocatalytic activities of samples were evaluated on the degradation of methyl orange (MO) under visible-light irradiation. The Bi2O3/BiVO4 exhibited much higher photocatalytic activities than pure BiVO4 and conventional TiO2 (P25). The result revealed that the three-dimensional heterojunction played a critical role in the separation of the electron and hole pairs and enhancement of the interfacial charge transfer efficiency, which was responsible for the enhanced photocatalytic activity.

Microwave-assisted synthesis of Mo-doped H1–xSr2Nb3–xMoxO10 (x = 0, 0.05, 0.1, 0.15 and 0.2) with high photocatalytic activity

H1–xSr2Nb3–xMoxO10 photocatalysts were synthesized using a microwave-irradiation-assisted ion-exchange reaction. The physicochemical properties of the photocatalysts were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and ultraviolet—visible spectroscopy (UV—vis). The photocatalytic activity of the H1–xSr2Nb3–xMoxO10 was evaluated by degrading methyl orange (MO) dye under light irradiation from a 40-W mercury lamp. The results proved that the Mo doping amount had an important effect on the photocatalytic activity of the catalysts. The highest photocatalytic activity was obtained when the doping amount was 15 mol%. Furthermore, the complex preparation process and lengthy time was simplified and shortened greatly.