A photosynthetic photoelectrochemical cell using phenazine methosulfate and phenazine ethosulfate as electron acceptors

Several recent studies have demonstrated that photosystem I (PSI), one of the two light-active complexes of photosynthesis, can be used as a light transducer in a biological photoelectrochemical cell. This paper examines the results of using phenazine methosulfate (PMS) and phenazine ethosulfate (PES) as an electron acceptor in such a cell. The PMS and PES have relatively high formal potentials compared to flavin mononucleotide (FMN) and other acceptors used in the past, yet the PMS and PES resulted in power outputs and conversion efficiencies second only to the use of FMN as an acceptor. The mechanism of action has been interpreted in terms of electroactive products of parent compounds formed during the normal function of the cell under illuminated conditions. For example, photolysis and cyclic voltammetry data demonstrate that pyocyanin (Py) [formal potential = -0.37 vs saturated calomel electrode (SCE) at pH 8.5], the photoproduct of PMS, is the electroactive species in cells containing PMS (formal potential = -0.19 vs SCE at pH 8.5). Similar phenomena were observed for PES and FMN. The power output of the cell results from about equal contributions from a cyclic photosynthetic component and a component caused by the direct photoreduction of the acceptor and reoxidation by sacrificial donors in the buffer. Future research directions are discussed in terms of designing cells that function purely in the photosynthetic or photochemical modes.     

Silafluorene‐based polymers for electrochromic and polymer solar cell applications

In this study, four novel silafluorene (SiF) and benzotriazole (Btz) bearing conjugated polymers are synthesized. In the context of electrochemical and optical studies, these polymers are promising materials both for electrochromic device (ECD) and polymer solar cell (PSC) applications. All of the polymers are ambipolar (both p‐ and n‐dopable) and multichromic. Electrochemistry experiments indicate that incorporation of selenophene instead of thiophene unit increases the HOMO energy level of the polymers. Power conversion efficiency of the PSCs reached 1.75% for PTBTSiF, 1.55% for PSBSSiF, 2.57% for PBTBTSiF, and 1.82% for PBSBSSiF. The hole mobilities of the polymers are estimated through space charge limited current (SCLC) model. PBTBTSiF has the highest hole mobility as 2.44 × 10^?3 cm² V s^?1. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1541–1547     

Improved photoelectrochemical hydrogen production over decorated titania with copper and nickel oxides by optimizing the photoanode and reaction characteristics

We optimized photocatalytic hydrogen production over TiO₂-based photocatalyst by varying the dopant (nickel and copper oxide), thin film active area, nature and concentration of sacrificial agents, and light intensity in a photoelectrochemical (PEC) cell/dye-sensitized solar cell (DSSC). Various characterization techniques have been used to investigate the structural, morphological, optical, and PEC behavior of single and codoped TiO₂. The TiO₂ decorated with both Cu and Ni oxides with active area of 1 cm² in a mixture of 5 vol % glycerol and 1 M KOH under light intensity of 100 mWcm^?2 produced the maximum hydrogen of 338.4 μmol cm^?2 for 2 h. The superior photocatalyst performance of this photocatalyst is attributed to its small crystallite size and large pore size, as confirmed by X-ray diffractometer, Transmission electron microscopy (TEM), and surface area of Brunauer-Emmet-Teller (S_BET). The absorption edges of this photocatalyst had the highest red shift compared with single doped and pure TiO₂ because of more indirect transitions of the photoexcited electrons, greater charge carrier separation, and lower recombination rate. The photoanode active area of 1 cm² with better photocatalytic performance correlated with the number of defects and grain boundaries. Glycerol shifted the conduction band of the photocatalyst to more negative flat potential compared with others. Increasing the concentration of glycerol further than 5 vol% saturated the photocatalyst active sites, increased photooxidation intermediates of glycerol, and reduced the hydrogen production. The light intensity had the maximum impact on the hydrogen production and could strongly control the number of charge carriers in both the PEC cell and the DSSC.     

Local studies of photoelectrochemical reactions at nanostructured oxides

The conversion of photon energy to chemical energy and vice versa requires the close arrangement of absorber/emitters and (electro)chemical reactions sites. This review considers local measurement techniques aiding in the design of efficient oxide systems for the utilization of light as energy source and as efficient detection principle. Artificial photoelectrochemical systems are often build on oxides as they are abundant and have semiconducting properties. However, no single oxide fulfills all requirements for an efficient conversion of sunlight to chemical energy and thus complex oxides are explored. These oxides might be obtained by doping oxides with other metal cations or by combining different oxides for absorbance and catalyzing the desired reaction, mainly water splitting. Due to the enormous amount of possible combinations combinatorial search for new material systems has been pursued and accelerated around the world making use of local photoelectrochemical characterization techniques in the screening step. Local detection schemes based on scanning electrochemical microscopy and scanning electrochemical cell microscopy also provide details about the kinetics for heterogeneous charge transfer and the release of soluble reaction products. During the recent years the scanning probe methods have been complemented by local detection of fluorescent reaction products that are formed by heterogeneous electron transfer reactions from and non-fluorescent precursor molecules. Such detection is possible with single molecule sensitivity and spatial resolution exceeding the diffraction limit (superresolution). Such approaches enabled the discovery of population within ensembles of metal oxide nanoparticles that are distinguished by the location and reactivity of their reaction sites. Optical techniques for measuring Faradaic currents hold great promise for the measurement of very low currents beyond the study of photoelectrochemistry of metal oxides.     

CdS quantum dot sensitized p-type NiO as photocathode with integrated cobaloxime in photoelectrochemical cell for water splitting

CdS sensitized NiO electrode was used as the photoactive cathode in a photoelectrochemical cell for water splitting,avoiding the use of a sacrificial electron donor.Photocurrent increment under visible light irradiation was observed after integration of[Co（dmgH）₂（4-Me-py）Cl]（1） to the photocathode,suggesting 1 could accept electrons from photoexcited CdS for water reduction and NiO could move the holes in the valence band of CdS to anode for water oxidation.     

The preparation and characterization of nanostructured TiO2-ZrO2 mixed oxide electrode for efficient dye-sensitized solar cells

The preparation of nanostructured mixed metal oxide based on a sol-gel method with surfactant-assisted mechanism, and its application for dye-sensitized solar cell (DSSC) are reported. The mixed zirconia (ZrO₂) and titania (TiO₂) mesoporous powder possessed larger surface area than the corresponding titania. For the UV action spectra of unsensitized photochemical cell, the mixed zirconia/titania electrode can absorb UV light below 380 nm, corresponding to band gap (E_g) around 3.27 eV, which is higher than that of pure component of titania (). Both of these improved properties, i.e., BET surface area and band gap, contributed to the improvement on a short-circuit photocurrent up to 11%, an open-circuit voltage up to 4%, and a solar energy conversion efficiency up to 17%, for the DSSC fabricated by mesoporous zirconia/titania mixed system when compared to the cell that was fabricated only by nanostructured TiO₂. The cell fabricated by 5 μm thick mixed TiO₂-ZrO₂ electrode gave the short-circuit photocurrent about 13 mA/cm², open-circuit voltage about 600 mV and the conversion efficiency 5.4%.     

An all-solid photoelectrochemical cell for the photooxidation of organic vapours under ultraviolet and visible light illumination

An all-solid photoelectrochemical cell has been tested in the photooxidation of methanol vapours as a proof-of-concept for the application of electrochemically enhanced photocatalysis in air treatment. The cell was based on a Nafion^®-impregnated microporous membrane that served as the solid polymer electrolyte. The working and reference electrodes (a TiO₂/WO₃-coated stainless steel mesh and AgCl-coated Ag wire, respectively) were adhered with the addition of a Nafion^® solution onto one face of the membrane, while the counter electrode (a plain stainless steel mesh) was attached to its opposite face. The use of an electrosynthesized TiO₂/WO₃ photoelectrode allowed the utilization of both UV and visible light. The device was tested by constant potential photoamperometry in air streams saturated with water or water–methanol vapours and the obtained photocurrent increased with increasing methanol levels, confirming the photoelectrochemical oxidation of methanol vapours under UV and visible light illumination.     

Effect of platinum on the photoelectrochemical behavior of lead oxide thin film

The effect of Pt on the photoelectrochemical behavior of lead oxide prepared from anodization of Pb-Pt alloy containing various concentrations of Pt has been studied. It is observed that, while Pt reduces the resistivity of the oxide film, it also reduces the photoconversion efficiency of the photoelectrochemical cell prepared from this material. The reason for this low efficiency is discussed. Received: 19 November 1997 / Accepted: 9 March 1998     

Nanostructured black cobalt coatings for solar absorbers

Nanocrystalline black cobalt electrically deposited onto a steel substrate from aqueous solution was investigated. The influence of electrolyte composition and operating parameters on the appearance and optical properties of the coat was studied. The deposition conditions that ensure the highest solar absorptance were optimized. The chemical composition of fabricated thin films before and after annealing at 400 °C was determined by energy dispersive X‐ray analysis (EDS) and XPS technique. The crystal structure analysis showed that the bulk composition of the films was mainly cobalt oxide. The surface analysis reveals that the topmost surface layers of the films are made of different cobalt compounds confirming the multivalence state of Co on the surface with an oxidation state of ≥ + 2. Scanning electron microscope (SEM) observation indicated that the surface morphology was changed from dendritic structure to lamellar at higher current density. The black cobalt film showed soft magnetic characteristicsand excellent optical properties to transform solar energy into thermal energy. Copyright © 2008 John Wiley & Sons, Ltd.     

Applicability of silanol to sensitizing dye for dye-sensitized solar cell

Applicability of silanols to dye-sensitized solar cells was investigated for the first time with bis(4-azobenzene)silanediol as a model compound. The silanol dye showed high adsorption ability on the surface of TiO₂ electrode and effective electron transfer from the light-excited dye to the electrode was confirmed, exhibiting the effectiveness of the silanol dyes for the sensitizers.     

方酸菁染料掺杂聚对苯乙炔太阳电池研究

本文把方酸菁染料掺杂在聚[2-甲氧基-5(2-乙基己氧基)对苯乙炔](MEH-PPV)共轭聚合物中,利用方酸菁染料在可见光的良好吸收以提高器件对光谱的利用。用Ti(OC3H7)4作为纳米TiO2前驱物直接和MEH-PPV、方酸菁染料(Hydroxy Squaraine,Sq)混合旋涂来制作连续的互穿网络器件。通过紫外-可见光吸收光谱得到掺杂后体系在650nm左右吸收得到加强,通过荧光测试发现体系MEH-PPV(5mg/mL)∶Sq(0.1mg/1mL)为4∶1(v∶v)掺杂Ti(OC3H7)4(80μL/mL)体积为50%时,荧光几乎被完全淬灭。测试了器件ITO/MEH-PPV/∶Sq∶TiO2/A,ITO/TiO2/MEH-PPV∶Squaraine∶TiO2/A l的光电性能,在AM=1.5,1000W/m2白光下单层器件的FF为0.31,Voc=54Mv,Isc=1.4mA,能量转换效率为0.008%。在同样条件下双层器件FF为0.12,Voc=203mV,Isc=0.048mA,能量转换效率为0.009%。     

High-performance silicon nanowire array photoelectrochemical solar cells through surface passivation and modification

Nanowire solar cells: Pt nanoparticle (PtNP) decorated C/Si core/shell nanowire photoelectrochemical solar cells show high conversion efficiency of 10.86 % and excellent stability in aggressive electrolytes under 1-sun AM 1.5 G illumination. Superior device performance is achieved by improved surface passivation of the nanowires by carbon coating and enhanced interfacial charge transfer by PtNPs.     

Thiochalcone substituted phthalocyanines for dye-sensitized solar cells: Relation of optical and electrochemical properties for cell performance

The new peripherally tetra-substituted metallophthalocyanines (MPcs, M=Zn, Co, Ni) bearing the chalcone, (E)-3-(4-hydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one, for dye-sensitized solar cells (DSSCs) were synthesized. FT-IR, ¹H NMR, ¹³C NMR, and UV–Vis spectroscopy techniques were utilized for characterization of all the MPcs. Electrochemical, optical and photovoltaic properties of all the MPcs as sensitizers were examined. Electrochemical studies reveal that while the ZnPc (4) and NiPc (6) give only Pc ring-based redox reactions, the CoPc (5) shows redox reactions based on both the central metal and the ring due to the metal 3d orbitals lying between the Pc HOMO and LUMO. The DSSC based on 5 gave the lowest power conversion efficiency (0.51%), perhaps due to the presence of a redox active central metal ion in the core of the complex, which results in a decrease electron transfer in the device. However, cells based on the other complexes including redox inactive central metal ions, which cannot reduce electron transfer, showed reasonable power conversion efficiencies of 1.27% and 1.11% for 4 and 6, respectively. The slight difference between the efficiencies can be attributed to higher molar extinction coefficient and narrower band gap of 4 than 6, which ensure a higher photocurrent and broader light absorption in the visible region.     

固态TiO2纳米太阳电池研究进展

本文介绍了固态TiO2纳米太阳电池的结构和工作有理，对近年来全固态纳米太阳电池，纳米TiO2膜、染料敏化剂的研究进展进行了综述。     

Dye-sensitized solar cell utilizing organic dyads containing triarylene conjugates

A series of organic dipolar compounds containing a donor (D), a bridge (B), and an acceptor (A), forming a D-B-A type of dyads, were synthesized by convenient methods and were utilized successfully on dye-sensitized solar cells. The central bridges were made of three linearly connected arylene groups, i.e., phenylenes or thiophenylenes. The donor groups were aromatic amines, i.e., either a diphenylamine or a naphthylphenylamine group. The acceptor group was a cyanoacrylic acid, which can be anchored onto the surface of TiO₂ in a photovoltaic device. These devices performed remarkably well, with a typical quantum efficiency of 5-7%, and optimal incident photon to current conversion efficiency (IPCE) exceeding 80%. The devices made with a naphthylphenylamine donor group performed slightly better than those made with a diphenylamine donor group. Compounds containing a phenylene-thiophenylene-phenylene bridge group performed better than those with other kinds of triarylene linkages. Their photochemical behaviors were analyzed by using time-dependent density functional theory (TDDFT) models with the B3LYP functional.     

Molecular engineering of organic dyes containing N-aryl carbazole moiety for solar cell

Organic dyes containing N-aryl carbazole moiety are designed and synthesized. Under standard global AM 1.5 solar condition, the JK-25 sensitized cell gave a short circuit photocurrent density (J_sc) of 11.50 mA cm⁻², an open circuit voltage (V_oc) of 0.68 V, a fill factor of 0.66, corresponding to an overall conversion efficiency η of 5.15%, and the maximum incident monochromatic photon-to-current conversion efficiency (IPCE) of 77% at 430 nm.