TiO2 Nanoparticles Produced by Electric-Discharge-Nanofluid-Process as Photoelectrode of DSSC

Self-made TiO₂ nanoparticles were used as photoelectrode material of dye sensitized solar cell. The TiO₂ thin film coats through spreading nanoparticles evenly onto the ITO glass via self-made spin-heat platform, and then TiO₂ thin film is soaked in the dye N-719 more than 12 h to prepare the photoelectrode device. The TiO₂ nanoparticles produced by electric-discharge-nanofluid-process have premium anatase crystal property, and its diameter can be controlled within a range of 20-50 nm. The surface energy zeta potential of nanofluid is from -22 mV to -28.8 mV, it is a stable particle suspension in the deionized water. A trace of surfactant Triton X-100 put upon the surface of ITO glass can produce a uniform and dense TiO₂ thin film and heating up the spin platform to 200 oC is able to eliminate mixed surfac-tant. Self-made TiO₂ film presents excellent dye absorption performance and even doesn't need heat treatment procedure to enhance essential property. Results of energy analysis show the thicker film structure will increase the short-circuit current density that causes higher conversion efficiency. But, as the film structure is large and thick, both the open-circuit voltage and fill factor will decline gradually to lead bad efficiency of dye-sensitized solar cell.     

硫化氧化两步法提高(110)取向ZnO纳米片比表面及其光电极应用

以硫代乙酰胺为硫源, 通过一种较温和的溶剂热法先将生长于氟掺杂的SnO₂ (FTO)导电玻璃上的ZnO纳米片硫化, 再将其在空气中高温焙烧氧化,利用ZnO/ZnS晶格的膨胀收缩效应使ZnO纳米片表面粗糙化,达到提高其比表面积的目的. 系统研究了该硫化氧化两步法中ZnO纳米片、硫化后的ZnS纳米片、硫化氧化后的ZnO纳米片薄膜的形貌、物相、比表面积及孔径分布的变化. 并将硫化氧化前后两种ZnO纳米片阵列薄膜制成染料敏化太阳电池的光电极, 分别对电池的电流密度-电压(J-V)特性进行了表征. 实验结果表明, 经过硫化氧化后的ZnO纳米片的比表面积大约是未经该处理的ZnO纳米片的2倍, 同时前者的太阳电池光电转换效率(IPCE)相对于后者提高33%.     

Mixed-phase WO3 Cocatalysts on Hierarchical Si-based Photocathode for Efficient Photoelectrochemical Li Extraction

Photoelectrochemical lithium (Li) extraction can be expected to provide a useful recycle of Li⁺ from waste Li-containing battery, but the process is limited by the photocathodes with poor Li⁺ absorption and low yield rate. Here, we have designed a hierarchical silicon (Si)-based photocathode with mixed-phase tungsten oxide (WO₃) cocatalysts for photoelectrochemical Li extraction under 1 sun illumination, achieving a high Li yield rate of ≈223.0 μg cm⁻² h⁻¹ and an excellent faradaic efficiency of 91.9 % at 0.0817 V versus Li^0/+ redox couple. The WO₃ cocatalysts with the mixture of amorphous and crystalline phase accelerates the Li⁺ insertion and precipitation and enriches the concentration of Li⁺ at the photocathode surface. This robust photoelectrochemical Li extraction system provides a new insight on designing green and efficient route for cyclic utilization of Li resources in the sustainable energy field.     

光电催化用于高附加值化学品合成

化石燃料的过度消耗导致了能源短缺和环境破坏,因此可再生清洁能源的开发已成为当务之急.在众多可再生能源中,太阳能因其环境友好,储量巨大且分布广泛等特点而引起了研究者们的兴趣.光电催化(PEC)是一种能够将可再生太阳能转化为化学能的方法,而最受关注的是通过PEC水分解来获得高附加值的氢能源.欲使PEC系统实现水分解,理论上...     

Synthesis and photoelectrochemical behavior of CdS quantum dots-sensitized indium-tin-oxide mesoporous film

In this paper, we reported an investigation on a new photoelectrode of quantum dots-sensitized solar cell (QDSC) combining indium-tin-oxide (ITO) mesoporous film and CdS quantum dots (QDs). The ITO mesoporous film was prepared by doctor-blade technique and CdS QDs attached on ITO mesoporous film were synthesized by successive ionic layer adsorption and reaction method. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscope, X-ray spectroscopy and UV-vis spectroscopy were used to characterize the samples. The results indicated that the ITO mesoporous film was uniform, crack-free and highly porous. And absorbance in visible region was enhanced after the deposition of CdS QDs on ITO mesoporous film. The photoelectrochemical property of the CdS QDs-sensitized ITO mesoporous film photoelectrode was investigated by forming a photoelectrochemical cell. Photocurrent-voltage measurement showed that the photoelectrode was efficient in the cell as working electrode.     

A review on metal-organic frameworks for photoelectrocatalytic applications

Semiconductor-based photoelectrocatalytic processes have attracted considerable research interest for solar energy collection and storage. Photoelectrocatalysis is a heterogeneous photocatalytic process in which a bias potential is applied to a photoelectrode, and thus the photoelectrocatalytic performance is closely related to the photoelectrode prepared by semiconductors. Among various semiconductors, metal-organic frameworks (MOFs) have attracted more and more attention because of their unique properties such as optical properties and adjustable structure. Herein, a comprehensive review on different MOFs (Ti-based, Zn-based, Co-based, Fe-based, Cu-based, and mixed metal-based MOFs) for heterogeneous photoelectrocatalysis is carried out and, in particular, the application of this technique for CO₂ conversion and water splitting is discussed. In addition, the challenges and development prospects of MOFs in photoelectrocatalysis are also presented.     

金属-有机框架材料在光电催化水分解领域的研究进展

光催化分解水是将太阳能转化为化学能的有效手段之一. 相比于粉末光催化, 采用H型电解池的光 电催化方法具有材料选择范围大、 载流子迁移和分离效率高、 电极易于回收等优点. 近年来, 金属有机框架 材料(MOFs)在光电催化水分解领域得到越来越多的应用. 相比于传统无机催化剂, MOFs光电极具有比表面积大、 结构易于调控等独特优势. 本文按照MOFs的应用形式分为纯MOFs、 MOFs与其它催化剂的复合结构和MOFs衍生物3类, 总结了近年来MOFs在光电催化水分解领域的研究现状和进展, 介绍了光催化/电催化领域的部分典型研究成果, 最后讨论了MOFs在光电催化水分解领域研究的重点和热点, 并对其未来发展做出了展望.     

Synthesis of nano-TiO2 assisted by diethylene glycol for use in high efficiency dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSSCs) consisting of anatase TiO_2 nanoparticles that were synthesized via a hydrothermal method was studied.The synthesized TiO_2 nanoparticles were characterized by X-ray diffraction(XRD),nitrogen sorption analysis,scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),and UV-vis spectroscopy.Then the J-Vcurve,electrochemical impedance spectroscopy(EIS),and open-circuit voltage decay(OCVD) measurement were applied to evaluate the photovoltaic performance of DSSCs.Compared with the commercial TiO_2nanoparticles(P25),the synthesized-TiO_2 nanoparticles showed better performance.By adding diethylene glycol(DEG) before the hydrothermal process,the synthesized TiO_2 nanoparticles(hereafter referred to as TiO_2-DEG particles) shows narrower size distribution,larger specific surface area,higher crystallinity,and less surface defects than TiO_2(DEG free) particles.The analysis of photovoltaic properties of DSSCs based on TiO_2-DEG particles showed that the recombination of electron-hole pairs was decreased and the trapping of carries in grain boundaries restrained.It was believed that the photoelectrode fabricated with the as-prepared TiO_2 nanoparticles improved the loading amount of dye sensitizers(N719).and enhanced the photocurrent of the DSSCs.As a result,the TiO_2-DEG particle based cells achieved a photo-to-electricity conversion efficiency(η) of 7.90%,which is higher than 7.53%for the cell based on TiO2(DEG free) and 6.59%for the one fabricated with P25.     

Photoelectrode characteristics of an organic bilayer in water phase containing a redox molecule

We have recently reported that the organic bilayer of 3,4,9,10-perylenetetracarboxyl-bisbenzimidazole (PTCBI, n-type semiconductor) and 29H,31H-phthalocyanine (H₂Pc, p-type semiconductor), which is a part of a photovoltaic cell, acts as a photoanode in the water phase (Abe et al., ChemPhysChem 5:716, [2004]); in that case, the generation of the photocurrent involving an irreversible thiol oxidation at the H₂Pc/water interface took place to be coupled with hole conduction through the H₂Pc layer, based on the photophysical character of the bilayer. In the present work, the photoelectrode characteristics of the bilayer were investigated in the water phase containing a redox molecule , where the photo-induced oxidation and reduction for the couple were found to take place at the bilayer. The photoanodic current involving the oxidation efficiently occurred at the interface of H₂Pc/water, similar to the previous example. In the view of the voltammograms obtained, it was noted that there are pin-holes in the H₂Pc layer of the bilayer, leading to a cathodic reaction with at the PTCBI surface especially in the dark; that is, the band bending at the PTCBI/water interface can essentially be reduced by applying a negative potential [e.g., < ∼ 0 V (vs Ag/AgCl)] to the PTCBI, when the cathodic reaction may take place through the conduction band of the PTCBI. Moreover, under that applied potential condition of irradiation, the photogenerated electron carrier part can move to the PTCBI surface, thus enhancing the reduction of .     

Chromium-doped titanium dioxide thin-film photoanodes in visible-light-induced water cleavage

A new method for the synthesis of nanocrystalline anatase Cr-doped TiO₂ colloids from nanotubes utilizing the hydrothermal ion-intercalation (HII) method has been devised using hydrothermal treatment in an acidic environment. To investigate the photoelectrochemical reaction that occurs when water is split into H₂ and O₂ under visible light, a Cr-doped TiO₂ thin film served as a model photoelectrode. The photoelectrochemical activity of Cr-doped TiO₂ was higher than that of the undoped sample. The photoelectrochemical activity of photoelectrodes increased drastically with increased chromium doping. A red shift in the band gap was induced by Cr doping of TiO₂. It was revealed that the Cr-doped TiO₂ photoelectrode was able to utilize a wide range of light in the visible region of the spectrum. At high Cr concentrations, the lower photoelectrochemical activity is attributed to the effect of Cr³⁺ ion recombination and excess Cr³⁺ ions forming secondary phase Cr₂O₃.