苯基磷酸联吡啶钌络合物敏化纳晶多孔TiO2薄膜电极光电性能研究

用有机光敏染料敏化半导体,通过染料分子的吸附功能基团与半导体相互作用,使染料分子与半导体表面之间建立电性耦合,进行有效的电荷转移,可以形成有机-半导体复合新型光电功能材料。联吡啶钌络合物有较强的可见光吸收、氧化还原性能可逆、氧化态稳定性高,是一类性能优越的有机光敏染料。近来许多研究发现,羧酸联吡啶钌的强吸附与TiO₂纳晶薄膜的大比表面相结合,导致光生电荷快速注入TiO₂导带达到有效的电荷分离,得到了接近100%的单色光光电流效率^[1]。为研究联吡啶钌分子的不同吸附功能基团与TiO₂纳晶薄膜表面的相互作用对提高光电性能的影响,本文报道苯基磷酸取代的联吡啶钌络合物敏化纳晶多孔TiO₂薄膜的光电性能。     

有机染料敏化网状二氧化钛纳米纤维微孔膜太阳能电池研究

利用静电纺丝技术, 在TiO₂纳米粒子上电纺一层网状TiO₂纳米纤维微孔膜作为光散射层, 并在TiO₂纳米粒子中掺杂少量MgO以抑制电子和空穴的复合, 得到TiO₂纳米纤维/纳米粒子复合光阳极用于染料敏化太阳能电池. 将这种光阳极分别与有机三苯胺染料SD2, SD3或钌染料N719及鹅脱氧胆酸(CDCA)共敏化时, 在AM 1.5 (100 mW/cm²)的模拟太阳光照射下, 染料敏化太阳能电池的光电转换效率达到6.35%～8.85%. 同时, 使用半固态电解质可以达到液态电解质90%的光电转换效率.     

电沉积表面修饰对染料敏化太阳电池微观性能影响机理研究

为了改善染料敏化太阳电池内电子的传输复合过程, 研究者尝试不同方法制备或改性TiO₂薄膜. 对TiO₂薄膜进行后处理, 在其表面引入一层小颗粒层, 是一种有效的方法并被广泛研究. 通过对TiO₂薄膜不同时间的电沉积表面修饰, 细致研究了表面修饰后染料敏化太阳电池微观性能的变化机制. 采用阳极氧化法在TiCl₃水溶液中对TiO₂薄膜进行电沉积后处理, 将溶液pH值调至2.2, 装置的反应速率由恒电位仪控制. 不同沉积时间电池带边移动以及电子传输复合的动力学过程, 借助强度调制光电流谱(IMPS)/强度调制光电压谱(IMVS)和电化学阻抗谱(EIS)等探测技术表征. 研究表明, 电沉积在TiO₂薄膜表面引入了大量浅能级陷阱态, 以致电势较高时电容随沉积时间延长增加明显. 不同时间的电沉积表面修饰在TiO₂薄膜表面形成了新的小颗粒层并改善了TiO₂颗粒间接触, 在改善电子注入及收集过程的同时, 也有效抑制了内部电子复合. IMPS/IMVS结果表明, 电沉积对动力学过程改善的效果受光强影响明显, 弱光下作用更为突出. 此外, 电池开路电压主要受带边移动及内部复合变化影响, 随沉积时间延长, 表面电荷的增多使TiO₂薄膜带边逐渐正移, 有效改善了光电流却限制了开路电压的提升. 在适合的电沉积时间下, 电沉积表面修饰可以同时改善光电流和光电压.     

染料敏化太阳能电池掺杂TiO2纳晶光阳极

染料敏化太阳能电池（dye-sensitized solar cells, DSC）效率高、制作简单、成本低,因此被认为是最有希望的第三代太阳能电池。DSC光阳极的主要作用是吸附染料、传输电子和提供电解质扩散通道,因此对DSC光电性能具有决定性作用。近年来,通过掺杂调控TiO₂光阳极的电子特性,从而提高DSC的光电效率受到广泛关注。本文对掺杂TiO₂光阳极的研究现状进行了综述,重点分析了非金属元素、过渡金属元素及主族元素的掺杂对TiO₂光阳极的能带结构、光吸收特性、染料吸附量、电子传输和界面复合过程以及所组装DSC光电性能的影响,分析了非金属元素共掺杂的协同效应。同时,对稀土元素掺杂TiO₂作为光谱转换材料提高DSC光吸收效率和光电转换效率进行了探讨,最后论文对掺杂TiO₂光阳极今后的研究重点和研究方向进行了展望。     

Y2O3/TiO2 "核-壳"结构在染料敏化太阳电池中的应用

在纳米TiO₂多孔薄膜表面包覆超薄绝缘体,形成"核-壳"结构的势垒层,是目前染料敏化太阳电池（DSC）光阳极改性的研究热点之一.本文选取氧化钇（Y₂O₃）作为包覆层材料,采用浸渍法对纳米TiO₂多孔薄膜进行修饰,研究Y₂O₃包覆处理对TiO₂薄膜微观结构及能带结构的影响;将浸渍法制备得到的Y₂O₃/TiO₂"核-壳"结构光阳极应用于DSC中,研究了饣覆层对电子传输复合以及DSC光电转换性能的影响.结果表明,Y₂O₃包覆处理后,薄膜的平带电势负移,且电子复合得到有效抑制,电子寿命增大,电池的开路电压明显提高.研究表明,适量引入Y₂O₃可以达改善电池性能的目的.     

通过扫描光电化学显微镜研究超分子光敏剂-二氧化钛薄膜系统的光诱导电子转移（英文）

在基于TiO₂的光阳极上枝接电荷转移通道仍然是太阳能到化学转换技术的一个迫切瓶颈。尽管进行了大量的尝试,但TiO₂作为有前途的光阳极材料仍然受到电荷传输动力学迟缓的影响。因此,一种组装策略涉及将金属卟啉基光敏剂分子(MP)轴向配位嫁接到表面改性的TiO₂纳米棒(TiO₂NRs)光阳极上,形成复合MP/TiO₂ NRs光电极。正如预期的那样,与单独的TiO₂NR和MPA/TiO₂NRs光电极相比,所得到的独特的MPB/TiO₂ NRs光电极具有明显提高的光电流密度。采用扫描光电化学显微镜(SPECM)和强度调制光电流光谱(IMPS)系统地评估了MP/TiO₂ NRs光电极的连续光激发电子转移(PET)动力学信息。通过数据拟合发现,在光照条件下,MPB/TiO₂ NRs的光电子转移速率(k_eff)常数比纯TiO₂ NRs高2.6倍...     

氧气氛烧结电极对染料敏化太阳电池微观性能影响机理研究

为了改善染料敏化太阳电池内电子的传输复合过程, 研究者尝试不同方法制备或改性TiO₂薄膜. 不同烧结气氛可以改变TiO₂薄膜的表面特性, 是一种有效的方法并被广泛研究. 采用两步烧结法制备氧气氛烧结TiO₂电极并应用于染料敏化太阳电池:第一步将电极在空气或氧气氛中510℃保温30 min以清除TiO₂薄膜中有机物; 第二步将电极进一步在氮气氛中510℃保温10 min以移除电极表面吸附的多余氧原子. 通过与空气烧结电池宏观性能及微观性能的对比, 细致研究了氧气氛烧结电极表面特性对染料敏化太阳电池传输复合微观动力学过程的影响机制. TiO₂薄膜表面特性及带边移动、电子传输复合过程的表征分别借助XPS能谱仪和强度调制光电流谱(IMPS)/强度调制光电压谱(IMVS)等探测技术完成. 结果表明, 氧气烧结电极Ti³⁺复合中心减少, 使电池内部电子复合得到有效抑制. 同时, 氧气烧结电极染料吸附量增加且导带边正移, 使得光生电子浓度升高, 膜内电子传输过程加快. 最终, 氧气烧结电极有效改善了电池光吸收效率、电子收集效率以及注入效率, 使电池效率由6.90%提升至7.53%.     

共吸附剂修饰TiO2电极及其在染料敏化太阳电池中的应用

在染料敏化太阳电池中, 引入共吸附剂通常有抑制染料聚集和提高电池性能的作用. 通过光谱电化学、线性伏安扫描和电化学阻抗谱(EIS)研究了几种以单羧酸基为吸附基团的共吸附剂对纳米TiO₂薄膜的修饰作用. 结果表明本实验中的共吸附剂均能使TiO₂平带电势负移, 并抑制TiO₂导带电子的复合, 其中胆酸类共吸附剂表现出较好的暗电流抑制性能. 适当浓度共吸附剂的引入能够提高N719染料敏化太阳电池的开路电压、填充因子和光电转换效率.     

新型含有多氰基受体单元的近红外敏化染料的合成及其光伏性能研究

本文分别以三苯胺、二甲基苯胺和吲哚啉单元为电子给体,设计并合成了3个新型D-π-A体系近红外敏化染料分子5C-1、5C-2和5C-3,并对其结构进行了表征,详细研究了在溶液中以及吸附到电极上的吸收光谱.该系列敏化染料在550—850 nm之间具有较强的吸收,尤其5C-3的吸收边带已达到954 nm.当该系列敏化染料吸附到TiO₂上时,吸收边带大幅红移,显示有利于染料捕获长波段区域的太阳光.通过循环伏安法,测定了染料的电化学性质,发现该系列敏化染料的最低未占有轨道(LUMO)能级与TiO₂导带并不匹配,因此选用导带能级更正的SnO₂作为阳极半导体材料进一步测试了该系列染料的光电性能,以发展具有优良性能的长波段响应的近红外敏化剂.     

纳米结构TiO2/3-甲基噻吩和2-噻吩甲酸共聚物复合膜电极光电化学性能

用光电流作用谱、光电流-电势图等光电化学方法研究了ITO/3-甲基噻吩和2-噻吩甲酸共聚物(CTCMT)膜电极和ITO/TiO₂/CTCMT复合膜电极的光电转换性质.结果表明,CTCMT膜为p型半导体,禁带宽度为2.36eV,价带位置为-5.52eV.在ITO/TiO₂/CTCMT复合膜电极中存在p-n异质结,在一定条件下异质结的存在有利于光生电子-空穴对的分离.CTCMT膜修饰ITO/TiO₂电极可使光电流增强,光电流起始波长红移至600nm以上,使宽禁带半导体电极的光电转换效率得到改善.     

Protonation effect on catalytic water oxidation activity of a mononuclear Ru catalyst containing a free pyridine unit

Two efficient single-site Ru water oxidation catalysts [Ru(bda)(pic)(Ln)](bda = 2,2'-bipyridine-6,6'-dicarboxylic acid, pic = picoline, L1 = 4,5-bipyridine-2,7-di-tert-butyl-9,9-dimethylxanthene, L2 = 4-pyridine-5-phenyl-2,7-di-tert-butyl-9,9-dimethylxanthene) were only synthesized containing different xanthene ligands at the axial site. These complexes have been thoroughly characterized by spectroscopic(UV-vis, NMR) and electrochemical(CV and DPV) techniques. Kinetic analysis proved that the mechanism of water oxidation comprises the water nucleophilic attack process on high-valence ruthenium species.It is found that the catalyst 1 displayed higher activity than catalyst 2 on water oxidation, caused by the protonation of the axial ligand L1 with a free pyridine.     

含1,3,4-噁二唑的联吡啶钌(Ⅱ)配合物的合成及光电性质研究(英文)

合成了2个新的含1,3,4-噁二唑官能团的联吡啶配体及其相应的钌髤配合物Ru(CPOD)(dcbpy)(NCS)2(Ru-1)和Ru(DPOD)(dcbpy)(NCS)2(Ru-2)(CPOD=4-羧基-4′-[2-(4-壬氧基苯基)-5-苯基-1,3,4-噁二唑]-2,2′-二联吡啶,DPOD=4,4′-二[2-(4-壬氧基苯基)-5-苯基-1,3,4-噁二唑]-2,2′-二联吡啶,dcbpy=4,4′-二羧基-2,2′-二联吡啶),并通过红外光谱、循环伏安、紫外可见吸收光谱、元素分析和光电流-光电压曲线实验对其结构和光电转化性质进行了表征。这些配合物的最大MLCT态吸收位于555nm,摩尔消光系数可达1.43×104L·mol-1·cm-1。它们的光化学和电化学性质表明:激发态能级与TiO2导带底能级匹配,电子能够注入到TiO2导带中。将它们敏化到纳米晶TiO2电极上,光电转化效率为2.4%。     

Light‐Driven Water Splitting Mediated by Photogenerated Bromine

Light‐driven water splitting was achieved using a dye‐sensitized mesoporous oxide film and the oxidation of bromide (Br^?) to bromine (Br₂) or tribromide (Br₃^?). The chemical oxidant (Br₂ or Br₃^?) is formed during illumination at the photoanode and used as a sacrificial oxidant to drive a water oxidation catalyst (WOC), here demonstrated using [Ru(bda)(pic)₂], ( 1 ; pic=picoline, bda=2,2′‐bipyridine‐6,6′‐dicarboxylate). The photochemical oxidation of bromide produces a chemical oxidant with a potential of 1.09 V vs. NHE for the Br₂/Br^? couple or 1.05 V vs. NHE for the Br₃^?/Br^? couple, which is sufficient to drive water oxidation at 1 (Ru^V/IV≈1.0 V vs. NHE at pH 5.6). At pH 5.6, using a 0.2 m acetate buffer containing 40 mm LiBr and the [Ru(4,4′‐PO₃H₂‐bpy)(bpy)₂]²⁺ ( RuP ²⁺, bpy=2,2′‐bipyridine) chromophore dye on a SnO₂/TiO₂ core–shell electrode resulted in a photocurrent density of around 1.2 mA cm^?2 under approximately 1 Sun illumination and a Faradaic efficiency upon addition of 1 of 77 % for oxygen evolution.     

Amphiphilic ruthenium sensitizers and their applications in dye-sensitized solar cells

Amphiphilic ligands 4,4'-bis(1-adamantyl-aminocarbonyl)-2,2'-bipyridine (L(1)), 4,4'-bis[5-[N-[2-(3beta-cholest-5-en-3-ylcarbamate-N-yl)ethyl]aminocarbonyl]]-2,2'-bipyridine (L(2)), 4,4'-bis[5-[N-[2-(3beta-cholest-5-en-3-ylcarbamate-N-yl)propyl]aminocarbonyl]]-2,2'-bipyridine (L(3)), and 4,4'-bis(dodecan-12-ol)-2,2'-bipyridine (L(4)) and their heteroleptic ruthenium(II) complexes of the type [Ru(II)LL(1)(NCS)(2)] (5), [Ru(II)LL(2)(NCS)(2)] (6), [Ru(II)LL(3)(NCS)(2)] (7), and [Ru(II)LL(4)(NCS)(2)] (8) (where L = 4,4'-bis(carboxylic acid)-2,2'-bipyridine) have been synthesized starting from dichloro(p-cymene)ruthenium(II) dimer. All the ligands and the complexes were characterized by analytical, spectroscopic, and electrochemical techniques. The performance of these complexes as charge-transfer photosensitizers in nanocrystalline TiO(2)-based solar cells was studied. When complexes 5-8 anchored onto a 12 + 4 microm thick nanocrystalline TiO(2) films, very efficient sensitization was achieved (85 +/- 5% incident photon-to-current efficiencies in the visible region, using an electrolyte consisting of 0.6 M butylmethylimidazolium iodide, 0.05 M I(2), 0.1 M LiI, and 0.5 M tert-butyl pyridine in 1:1 acetonitrile + valeronitrile). Under standard AM 1.5 sunlight, the complex 8 yielded a short-circuit photocurrent density of 17 +/- 0.5 mA/cm(2), the open-circuit voltage was 720 +/- 50 mV, and the fill factor was 0.72 +/- 0.05, corresponding to an overall conversion efficiency of 8.8 +/- 0.5%.     

Self‐Assembled Amphiphilic Water Oxidation Catalysts: Control of O−O Bond Formation Pathways by Different Aggregation Patterns

The oxidation of water to molecular oxygen is the key step to realize water splitting from both biological and chemical perspective. In an effort to understand how water oxidation occurs on a molecular level, a large number of molecular catalysts have been synthesized to find an easy access to higher oxidation states as well as their capacity to make O?O bond. However, most of them function in a mixture of organic solvent and water and the O?O bond formation pathway is still a subject of intense debate. Herein, we design the first amphiphilic Ru‐bda (H₂bda=2,2′‐bipyridine‐6,6′‐dicarboxylic acid) water oxidation catalysts (WOCs) of formula [Ru^II(bda)(4‐OTEG‐pyridine)₂] ( 1 , OTEG=OCH₂CH₂OCH₂CH₂OCH₃) and [Ru^II(bda)(PySO₃Na)₂] ( 2 , PySO₃^?=pyridine‐3‐sulfonate), which possess good solubility in water. Dynamic light scattering (DLS), scanning electron microscope (SEM), critical aggregation concentration (CAC) experiments and product analysis demonstrate that they enable to self‐assemble in water and form the O?O bond through different routes even though they have the same bda^2? backbone. This work illustrates for the first time that the O?O bond formation pathway can be regulated by the interaction of ancillary ligands at supramolecular level.     

Systematic tuning of the reactivity of [RuII(terpy)(N^N)Cl]Cl complexes

Abstract

The substitution behavior of the [Ru^II(terpy)(ampy)Cl]Cl (terpy = 2,2′:6′,2′′-terpyridine, ampy = 2-(aminomethyl)pyridine) complex in water with several bio-relevant ligands such as chloride, thiourea and N,N′-dimethylthiourea, was investigated and compared with the reactivity of the [Ru^II(terpy)(bipy)Cl]Cl and [Ru^II(terpy)(en)Cl]Cl (bipy =2,2′-bipyridine and en?=?ethylenediamine) complexes. Earlier results have shown that the reactivity and pK_a values of Ru(II) complexes can be tuned by a systematic variation of electronic effects provided by bidentate spectator chelates. The reactivity of both the chlorido and aqua derivatives of the studied Ru(II) complexes increases in the order [Ru^II(terpy)(bipy)X]^+/2+?<?[Ru^II(terpy)(ampy)X]^+/2+?<?[Ru^II(terpy)(en)X]^+/2+. This finding can be accounted for in terms of π back-bonding effects provided by the pyridine ligands. The activation parameters for all the studied reactions support an associative interchange substitution mechanism.     

Efficient charge separation in TiO2 films sensitized with ruthenium(II)-polypyridyl complexes: hole stabilization by ligand-localized charge-transfer states

We have studied the interfacial electron-transfer dynamics on TiO(2) film sensitized with synthesized ruthenium(II)-polypyridyl complexes--[Ru(II)(bpy)(2)(L(1))] (1) and [Ru(II)(bpy)(L(1))(L(2))] (2), in which bpy=2,2'-bipyridyl, L(1)=4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol, and L(2)=4-(N,N-dimethylaminophenyl)-2,2'-bipyridine-by using femtosecond transient absorption spectroscopy. The presence of electron-donor L(2) and electron-acceptor L(1) ligands in complex 2 introduces lower energetic ligand-to-ligand charge-transfer (LLCT) excited states in addition to metal-to-ligand (ML) CT manifolds of complex 2. On photoexcitation, a pulse-width-limited (<100 fs) electron injection from populating LLCT and MLCT states are observed on account of strong catecholate binding on the TiO(2) surface. The hole is transferred directly or stepwise to the electron-donor ligand (L(2)) as a consequence of electron injection from LLCT and MLCT states, respectively. This results an increased spatial charge separation between the hole residing at the electron-donor (L(2)) ligand and the electron injected in TiO(2) nanoparticles (NPs). Thus, we observed a significant slow back-electron-transfer (BET) process in the 2/TiO(2) system relative to the 1/TiO(2) system. Our results suggest that Ru(II) -polypyridyl complexes comprising LLCT states can be a better photosensitizer for improved electron injection yield and slow BET processes in comparison with Ru(II)-polypyridyl complexes comprising MLCT states only.     

Ruthenium(II) Complexes with Three Different Diimine Ligands

The synthesis of tri-heteroleptic complex of Ru(II) with diimine ligands is describe. Ten compounds [Ru(R₂bpy) (biq) (L)][PF₆]₂ (R = H, CH₃); L = 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (Me₂bpy), 2,2′-bipyrimidine (bpm), 2,2′-biisoquinoline (biiq), 1,10-phenanthroline (phen), dipyrido[3,2-c:2′,3′-e]pyridazine (taphen), 2,2′-biquinoline (biq), 6,7-dihydrodipyrido[2,3-b:3,2-j][1,10]-phenanthroline (dinapy), 2-(2[pyridyl)quinoline (pq), 1-(2-pyrimidyl)pyrazole] (pzpm), 2,2′-biimidazole (H₂biim) are characterized by elemental analysis, electronic and ¹H-NMR spectroscopy. The relative photosustitution rates of biq in MeCN are given at three temperatures.     

Synthesis of ruthenium and palladium complexes from glycosylated 2,2′-bipyridine and terpyridine ligands

A series of glucosylated mono- and di-(1H-1,2,3-triazol-4-yl)pyridines were prepared from glucosyl azides and 2-ethynyl and 2,6-diethynyl pyridine via Click reaction. Glucosylation of the silver salt of 4-hydroxy-2,2′-bipyridine with acetobromoglucose afforded the corresponding glucosylated 2,2′-bipyridine. Treatment of five examples of the latter pyridine ligands with [cis-Ru(bipy)2Cl₂], [Ru(tpy)Cl₃] or [Pd(COD)Cl₂] gave the corresponding ruthenium(II) and palladium(II) complexes in 62%-quantitative yield.     

TiO2纳米颗粒对钌(II)三联吡啶配合物光损伤小牛胸腺DNA能力的影响

由于极短的激发态寿命, 钌(II)三联吡啶配合物对脱氧核糖核酸(DNA)的光损伤能力低下. 设计合成了三个钌(II)三联吡啶配合物[Ru(ttp)(tpy)]^2＋ (1), [Ru(ttp-COOH)(tpy)]^2＋ (2)和[Ru(ttp-COOH)(tpy-pyr)]^2＋ (3), 其中tpy为2,2':6',2"-三联吡啶, ttp为4′-(4-甲苯基)-2,2':6',2"-三联吡啶, ttp-COOH为4′-(4-羧基苯基)-2,2':6',2"-三联吡啶, tpy-pyr为4'-(1-芘基)-2,2':6',2"-三联吡啶. 比较了TiO₂纳米颗粒对它们光损伤小牛胸腺DNA的影响. 发现TiO₂纳米颗粒在空气和氩气条件下均可显著提高配合物3光损伤DNA的能力. TiO₂纳米颗粒和配合物3间的光诱导电子转移作用及其该作用生成的钌(III)物种可能是促进配合物3对DNA光损伤的主要原因.