Extensive enhancement in power conversion efficiency of dye-sensitized solar cell by using Mo-doped TiO2 photoanode

Journal of Solid State Electrochemistry - In this work, we have synthesized Mo-doped TiO2 nanoparticles by sol–gel method and used them as photoanode in dye-sensitized solar cells (DSSCs). Mo...     

Porphyrin-sensitized nanoparticulate TiO2 as the photoanode of a hybrid photoelectrochemical biofuel cell

Porphyrin-sensitized nanoparticulate TiO(2) on conducting glass has been investigated as a photoanode material for a new cell that converts light energy into electricity. The cell is a hybrid of a dye-sensitized nanoparticulate semiconductor photoelectrochemical solar cell, and a biofuel cell that oxidizes glucose. Porphyrin molecules excited by light inject electrons into the photoanode, from where they enter the external circuit. The resulting porphyrin radical cations are reduced by NADH in aqueous buffer, ultimately regenerating the photoanode and producing NAD(+). Glucose dehydrogenase oxidizes glucose, and in the process recycles NAD(+) back to NADH. The photoanode is coupled with a suitable cathode to make a functioning cell (Hg/Hg(2)SO(4) was employed for evaluation purposes). The cell produces 1.1 V at open circuit and has a fill factor of 0.61. These values are both significantly higher than those for a previously reported cell of a similar type based on an SnO(2) electrode.     

Improving the performance of a membraneless and mediatorless glucose-air biofuel cell with a TiO2 nanotube photoanode

A new light-driven, membraneless and mediatorless glucose-air biofuel cell combining a TiO(2) nanotube photoanode with an enzyme-modified biocathode has been successfully constructed. Upon UV light illumination, the open-circuit voltage and the maximum power density of the cell reach 1.00 V and 47 μW cm(-2), respectively.     

Rose bengal-sensitized ZrO2 photoanode for dye-sensitized solar cell

Journal of Solid State Electrochemistry - The present work reports the first demonstration of zirconium oxide (ZrO2) as a photoanode and rose bengal (RB) as a sensitizer. ZrO2 photoanode films were...     

Dual-photoelectrode photoelectrochemical cell exploiting a photoanode based on cadmium sulfide and anatase TiO2 photocatalysts for tannic acid detection

Journal of Solid State Electrochemistry - Photoelectrochemical systems based on half-photoelectrochemical cells have been widely exploited in the development of analytical methods. However, the...     

Reduction of TiO2 with Hydrogen Plasma

Experiments were performed in a thermal plasma furnace to examine the reduction of TiO₂ by hydrogen plasma. The plasma gas composition was 50% hydrogen–50% argon, the plasma torch input power was 13 kW, the TiO₂ initial mass was 10 g and the processing time was varied from 10 to 90 min. The reaction product contained between 67% and 73% titanium by mass for all tests. This level of reduction was consistent with chemical equilibrium modeling. There was no detectable enhancement of reduction due to the presence of atomic hydrogen. The Ti-O microstructures produced were characterized using quantitative SEM analysis. The microstructures showed a number of similarities with structures described by previous researchers.     

静电喷雾法制备高效染料敏化太阳能电池的二氧化钛光阳极

TiO2光阳极膜是染料敏化太阳能电池（DSSC）的核心部件之一,它对电池的光电转换效率起决定性作用．TiO2电极一般采用刮涂法和丝网印刷法制备．近3年,通过静电喷雾制备光阳极的方法得到国内外学者的关注．静电喷雾制备光阳极会受到多种因素的影响,如电压、流速、悬浮液浓度、喷雾距离以及喷雾时间等．但这些因素对成膜和DSSC器件性能的影响却没有得到全面的研究或者报道．本文使用静电喷雾法制备了多孔TiO2纳米膜,并研究了以其为电极的电池器件特性．经过超声充分分散的稳定TiO2乙醇悬浮液在高电压下喷雾到导电玻璃上成膜．通过改变电喷雾距离,得到了具有不同形貌的TiO：光阳极膜,并解释了其形成的机理及其对电池性能的影响．研究还表明,光阳极膜的TiC14处理能够很好地改善电池性能．通过优化,基于流速为0．8mL／h、电喷雾距离和时间分别为2．2cm和8min条件下制备的光阳极,结合TiC14处理,组装的电池在模拟太阳光源AM1．5G下光电转化效率达6．24％．     

A diketopyrrolopyrrole dye-based dyad on a porous TiO2 photoanode for solar-driven water oxidation

Dye-sensitised photoanodes modified with a water oxidation catalyst allow for solar-driven O₂ evolution in photoelectrochemical cells. However, organic chromophores are generally considered unsuitable to drive the thermodynamically demanding water oxidation reaction, mainly due to their lack of stability upon photoexcitation. Here, the synthesis of a dyad photocatalyst (DPP-Ru) consisting of a diketopyrrolopyrrole chromophore (DPPdye) and ruthenium-based water oxidation catalyst (RuWOC) is described. The DPP-Ru dyad features a cyanoacrylic acid anchoring group for immobilisation on metal oxides, strong absorption in the visible region of the electromagnetic spectrum, and photoinduced hole transfer from the dye to the catalyst unit. Immobilisation of the dyad on a mesoporous TiO₂ scaffold was optimised, including the use of a TiCl₄ pretreatment method as well as employing chenodeoxycholic acid as a co-adsorbent, and the assembled dyad-sensitised photoanode achieved O₂ evolution using visible light (100 mW cm⁻², AM 1.5G, λ > 420 nm). An initial photocurrent of 140 μA cm⁻² was generated in aqueous electrolyte solution (pH 5.6) under an applied potential of +0.2 V vs. NHE. The production of O₂ has been confirmed by controlled potential electrolysis with a faradaic efficiency of 44%. This study demonstrates that metal-free dyes are suitable light absorbers in dyadic systems for the assembly of water oxidising photoanodes.

Construction of a water oxidising photoanode with an organic chromophore-catalyst dyad.     

Pt/TiO2光催化分解四硼酸钾水溶液制氢

研究了以四硼酸钾溶液作反应体系，在1%Pt／TiO2光催化剂的作用下光催化分解水制氢的反应，发现该体系能使放氢速率明显提高．放氢速率还随B4O7^2-浓度的增大而增大．在此基础上，还对B4O7^2-的作用机理进行了探讨，BRO7^2-在该反应体系中主要是通过物理作用有效的阻止了逆反应的发生，从而使放氢速率得以提高．     

Effect of titanium isopropoxide addition in low-temperature cured TiO2 photoanode for a flexible DSSC

In this study, titanium isopropoxide (TIPP) was employed as a binder for low-temperature processed photoanode of a flexible dye sensitized solar cell. The coating paste for dip-coating method was prepared comprising commercially available TiO₂ nanoparticles, TIPP and small amount of water. Effect of binder addition was compared at three different TIPP to TiO₂ nanoparticle molar ratios; 0.05, 0.1 and 0.3. By adding TIPP molecules directly to the coating paste, flexible photoanodes were successfully prepared. An optimum TIPP to TiO₂ particle ratio was selected considering the particle dispersion stability in the paste and the microstructure of prepared photoanode. The photoanode prepared using the paste with optimized composition showed highest photoconversion efficiency of 1.96 % from a unit cell.     

Porous Si/TiO2 nanowire photoanode for photoelectric catalysis under simulated solar light irradiation

Porous Si/TiO₂ nanowire photoanodes were prepared by a combination of hydrothermal synthesis and metal‐assisted chemical etching. Characterization of samples was conducted using scanning electron microscopy and X‐ray diffraction, the results showing that a porous Si/TiO₂ heterojunction structure was synthesized. Diffuse reflection spectra show that the porous Si/TiO₂ nanowire photoanodes have a strong absorption. Photocurrent measurement shows that the photocurrent of the porous Si/TiO₂ nanowire photoanodes at 6 h is higher than that of others in the measuring region. The photoelectric catalysis (PEC) activities of porous Si/TiO₂ nanowire photoanodes were evaluated in degradation experiments of methylene blue under simulated solar light irradiation, and the sample at 6 h shows the highest PEC activity. Meanwhile, the PEC activity of the porous Si/TiO₂ nanowire photoanode is higher than that of the single direct photocatalysis process or electric catalysis. The mechanism of the PEC of the porous Si/TiO₂ nanowire photoanodes has been explained.     

Mesoporous Foam TiO2 Nanomaterials for Effective Hydrogen Production

Hydrolysis of TiCl₄ in a diether‐functionalized imidazolium ionic liquid (IL), namely 1‐methyl‐3‐[2‐(2‐methoxy(ethoxy)ethyl]imidazolium methane sulfonate (M(MEE)I ? CH₃SO₃), results in a heterostructured organic/inorganic and sponge‐like porous TiO₂ material. The thermal treatment (300 °C) followed by calcination (500 °C) affords highly porous TiO₂. The characterization of the obtained samples (with and without IL, before and after calcination) by XRD, SEM, and TEM reveals TiO₂ anatase crystalline phases and irregular‐shaped particles with different porous structures. These hierarchical‐structured mesoporous TiO₂ nanomaterials were employed as efficient photocatalysts in the water‐splitting process, yielding up to 1304 μmol g^?1 on hydrogen production.     

Hydrogen photoevolution from water-methanol on Ru/TiO2

Summary In situ ruthenium photodeposition on anatase TiO₂ was found to be an efficient method of obtaining Ru/TiO₂ powders highly active in hydrogen photoevolution from water-methanol. The efficiency of the catalyst was higher when the TiO₂ powder was subjected to a cation exchange prior to illumination in water-methanol. Reaction conditions were optimized; it was found that the most active sample was TiO₂ covered with 0.75 wt% Ru. Anatase TiO₂ itself was found to be porous with an average cylindrical pore radius of 37 Å. SEM and electron microprobe analysis showed that the photodeposition of ruthenium on the porous substrate resulted in a nonhomogeneous distribution on the TiO₂ surface. The size of ruthenium islets seems to influence the stability of Ru/TiO₂ catalysts in hydrogen photoevolution from water-methanol.

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Photoevolution von Wasserstoff aus Wasser-Methanol auf Ru/TiO₂

Zusammenfassung Es wurde festgestellt, daß diein situ Photodepositierung von Ruthenium auf Anatas-TiO₂ eine effiziente Methode darstellt, um Ru/TiO₂-Pulver herzustellen, das eine hohe Aktivität bei der Photoevolution von Wasserstoff aus Wasser-Methanol besitzt. Die Effizienz des Katalysators war höher, wenn das TiO₂-Pulver vor der Bestrahlung einem Kationenaustausch unterworfen wurde. Die Reaktionsbedingungen wurden optimiert; TiO₂, bedeckt mit 0.76 Gew% Ru, zeigte sich als aktivster Katalysator. Anatas-TiO₂ selbst erwies sich als porös mit einem mittleren zylindrischen Porenradius von 37 Å. Mittels SEM und Mikrosondenanalyse wurde festgestellt, daß die Photodepositierung von Ruthenium auf dem porösen Substrat eine nichthomogene Verteilung auf der TiO₂-Oberfläche ergibt. Das Ausmaß und die Größe der Ruthenium-Anhäufungen scheinen die Stabilität von Ru/TiO₂-Katalysatoren bei der Photoevolution von Wasserstoff aus Wasser-Methanol zu beeinflussen.

     

Enhanced electron collection in photoanode based on ultrafine TiO2 nanotubes by a rapid anodization process

The separated and ultrafine TiO₂ nanotubes are fabricated by a modified rapid anodization method, which cannot be achieved through conventional anodization. Then, model dye-sensitized solar cells based on the prepared TiO₂ nanotubes and commercial TiO₂ nanoparticles (P25) are investigated, and a discrepancy is discovered between the light-harvesting capability and the power conversion efficiency. The charge transport and recombination are studied by the electrochemical impedance spectroscopy and the open-circuit voltage decay technique. Results show that the nanotube photoanode owns a longer electron diffusion length and a larger electron lifetime than the nanoparticle one, which can compensate for the loss of light absorption. The enhanced electron collection efficiency observed is attributed to the facilitated charge carrier pathways in the photoanode composed by the separated TiO₂ nanotubes fabricated in this work. Therefore, the TiO₂ nanotubes synthesized by this method are verified to have good electronic properties, which might find applications not only in photovoltaic, but also in catalysis, sensors, and other areas.     

ZnO nanowire arrays coating on TiO2 nanoparticles as a composite photoanode for a high efficiency DSSC

A novel composite photoanode with ZnO nanowire arrays coating on the top of TiO(2) nanoparticles is fabricated, and an efficiency of 4.52% is achieved for the composite cell, far higher than both 0.90% of the ZnO nanowire cell and 3.56% of the TiO(2) nanoparticle cell. The improved efficiency is resulted from the high surface area of nanoparticles, as well as fast electron transport and light scattering effect of nanowires.     

TiO2光催化分解水制氢研究进展

综述了近几年改善TiO2光催化分解水制氢的方法措施.向水中添加供电子物质可减少光生电子与空穴的复合,添加碳酸盐或碘化物有利于光生电子与空穴分离;TiO2表面沉积适量的金属颗粒也有利于实现电子和空穴分离,但沉积太多的金属颗粒不但降低TiO2对光的吸收而且还可能成为光生电荷复合的中心;掺杂合适的金属离子通过形成杂质能级可把TiO2的吸光范围至拓宽可见光,掺杂非金属元素使TiO2的带隙(Eg)变窄,从而使TiO2的吸光红移更明显,但掺杂离子有可能成为光生电荷复合的中心;染料敏化或半导体复合有利于实现电荷分离,提高光电转换效率.将多种修饰方法有机结合起来制取氢足目前的一个研究方向,最后分析了未来的研究重点.     

利用甘油废水Pt/TiO2光催化制氢

研究了以甘油为电子给体在Pt/TiO2上光催化生成氢的反应.结果表明甘油能显著地提高光催化放氢效率,并且其自身的降解活性也很好.研究了反应时间、甘油起始浓度、溶液pH值、甘油废水中共存物对光催化放氢的影响.甘油光催化降解最终产物是H2O和CO2,检测到了甘油醛、羟基乙醛、羟基乙酸、甲醛等中间产物.探讨了可能的反应机理.     

Pt/TiO2光诱导催化重整乙醇制氢

对无氧条件下Pt/TiO2光诱导催化重整乙醇制氢进行了系统的研究，结果表明，乙醇的光催化重整制氢反应受催化剂表面化学状态，反应体系的pH值，浓度的影响较大，而受反应体系温度的影响较小，在运动XRD，XPS，HNMR等技术手段对催化剂和反应产物进行表征，分析的基础上，提出了无氧条件下乙醇光催化重整制氢可能的反应机理。