Viologen-modified platinum clusters acting as an efficient catalyst in photocatalytic hydrogen evolution.
Viologen-modified platinum clusters acting as an efficient catalyst in photocatalytic hydrogen evolution.
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DOI：
10.1021/jp065215v
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发表时间：
2006-11
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影响因子：
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通讯作者：
Hiroaki Kotani;K. Ohkubo;Y. Takai;S. Fukuzumi
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文献类型：
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作者：
Hiroaki Kotani;K. Ohkubo;Y. Takai;S. Fukuzumi
以甲基紫精-烷基乙醇胺（MVA ~（2+））功能化的水溶性铂团簇和简单的电子给体Acr ~（+）-Mes（9-mesityl-10-methylacridinium ion，Acr ~（+）-Mes）为载体，构建了一个以二氢烟酰胺辅酶（NADH）为牺牲剂的高效光催化体系.通过透射电子显微镜（TEM）测定铂核的平均直径为R（CORE）= 1.9 nm，标准偏差σ = 0.5 nm。结果表明，在其它条件相同的情况下，MVA ~（2+）修饰的铂簇（MVA ~（2+）-PtC）光催化体系的析氢速率比MVA ~（2+）-PtC光催化体系的析氢速率快10倍。用激光闪光光解实验成功地探测到了NADH自由基阳离子。由NAD* 引起的吸光度的衰减（由NADH*+的去质子化产生）与由Acr*-Mes引起的吸收带的出现一致。这表明从NAD* 到Acr+-Mes的电子转移得到Acr*-Mes，其经历MVA 2 +-PtC的电子转移还原，导致有效的析氢。
A highly efficient photocatalytic system for hydrogen evolution with dihydronicotinamide coenzyme (NADH) as a sacrificial agent in an aqueous solution has been constructed by using water-soluble platinum clusters functionalized with methyl viologen-alkanethiol (MVA2+) and a simple electron-donor dyad, 9-mesityl-10-methylacridinium ion (Acr+-Mes), which is capable of fast photoinduced electron transfer but extremely slow back electron transfer. The mean diameter of the platinum core was determined as R(CORE) = 1.9 nm with a standard deviation sigma = 0.5 nm by transmission electron microscopy (TEM). As a result, the hydrogen-evolution rate of the photocatalytic system with MVA2+-modified platinum clusters (MVA2+-PtC) is 10 times faster than the photocatalytic system with the mixture of the same amount of MVA2+ and platinum clusters as that of MVA2+-PtC under otherwise the same experimental conditions. The radical cation of NADH has been successfully detected by laser flash photolysis experiments. The decay of the absorbance due to NAD*, produced by the deprotonation from NADH*+, coincides with the appearance of the absorption band due to Acr*-Mes. This indicates electron transfer from NAD* to Acr+-Mes to give Acr*-Mes, which undergoes the electron-transfer reduction of MVA2+-PtC, leading to the efficient hydrogen evolution.