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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Charge injection into nanostructured TiO2 electrodes from the photogenerated reduced form of a new Ru(II) polypyridine compound: the 'anti-biomimetic' mechanism at work
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Charge injection into nanostructured TiO2 electrodes from the photogenerated reduced form of a new Ru(II) polypyridine compound: the 'anti-biomimetic' mechanism at work

机译：从一种新的Ru（II）聚吡啶化合物的光生还原形式向纳米结构TiO2电极中注入电荷：“抗仿生”机制在起作用

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摘要

The charge transfer dynamics involving a new Ru(II) polypyridine complex (1), developed to generate highly oxidizing photoholes for water oxidation, was studied by electrochemical, photoelectrochemical and spectroscopic means. Mesoporous TiO2 electrodes sensitized with complex 1, under 1 sun illumination (420 nm cut-off filter) and a moderate applied bias (0.3 V vs. SCE), in ACN/0.1 M LiI as a sacrificial electron donor reach an anodic photocurrent of similar to 0.2 mA cm(-2) with 3% photon-to-current conversion efficiency. When 0.1 M aqueous sodium ascorbate (pH 3) is used instead of iodide, the photocurrent increases to similar to 0.7 mA cm(-2) and up to 1 mA cm(-2) if the concentration of ascorbate is increased to 0.5 M, explainable with a modification of the charge injection mechanism. This is the photoelectrochemical evidence, in the heterogeneous phase, of the so-called "anti-biomimetic" pathway, confirmed in transient absorption spectroscopy by a long lived sharp bleaching at 480 nm and a narrow absorption between 500 and 550 nm, characteristic fingerprints of the photogenerated reduced state (1(-)). After the formation of *1/TiO2, reductive quenching by ascorbate occurs, not observed in LiI where the classic oxidative quenching takes place. Due to the modest excited state oxidation potential, electron transfer to TiO2 is thermodynamically more favorable from 1(-) than *1. Lastly, experiments performed with sensitized SnO2 photoanodes, where *1 undergoes the usual oxidative quenching, by charge transfer to the conduction band of the metal oxide allowed us to verify the interaction between 1(+) and IrO2 nanoparticles, grafted onto the surface in order to drive photoinduced water oxidation.
机译：通过电化学，光电化学和光谱学方法研究了涉及一种新的Ru（II）聚吡啶配合物（1）的电荷转移动力学，该复合物被开发用于产生高氧化性的光孔以进行水氧化。以ACN / 0.1 M LiI作为牺牲电子给体的，在1种太阳光照射下（420 nm截止滤光片）和适度施加的偏压（0.3 V vs. SCE），在1号日光照射下以复合物1敏化的介孔TiO2电极，其阳极光电流类似至0.2 mA cm（-2），光子至电流转换效率为3％。当使用0.1 M抗坏血酸钠水溶液（pH 3）代替碘化物时，如果抗坏血酸盐的浓度增加到0.5 M，则光电流将增加到类似于0.7 mA cm（-2）并达到1 mA cm（-2），可以通过修改电荷注入机制来解释。这是所谓“抗仿生”途径在异相阶段的光电化学证据，在瞬态吸收光谱法中通过在480 nm处存在长寿命的尖锐漂白和在500至550 nm之间的窄吸收，光生还原态（1（-））。 * 1 / TiO2形成后，发生了抗坏血酸的还原淬灭，在发生经典氧化淬灭的LiI中没有观察到。由于适度的激发态氧化电势，从1（-）到电子到TiO2的电子转移比* 1更有利。最后，通过对敏化的SnO2光电阳极进行的实验，其中* 1经历了通常的氧化猝灭，通过电荷转移到金属氧化物的导带上，我们可以验证1（+）和IrO2纳米粒子之间的相互作用，依次将其接枝到表面上驱动光致水氧化。

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