The photoinduced water-splitting reaction is a promising approach for converting sustainable sunlight into chemical energy. However, the high overpotential for traditional metal catalysts to drive oxygen evolution limits the conversion efficiency. Plasmonic metal–semiconductor systems can potentially overcome this problem, as hot electrons generated by localized surface plasmon resonance are rapidly injected into the semiconductor and hot holes are concentrated to oxidize water. The intermediates and pathways of such plasmon-induced water oxidation are currently unknown. Herein, taking Au-nanostructured TiO₂ as a prototype, we investigated distinct spectral characteristics of water oxidation intermediates at electrochemical potentials close to the flat-band potential of TiO₂ using in situ electrochemical surface-enhanced Raman spectroscopy. Au–O stretching vibrations are attributed to the initial oxidized-state intermediate Au(OH)₃ at pH 0 or 13 and the highest-energy intermediate AuOOH at pH 7. The existence of AuOOH provides the first robust experimental evidence for the accelerated four-electron multistep reaction via plasmon-assisted water oxidation.

中文翻译：

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TiO ₂单晶上Au纳米二聚体结构上等离子诱导水氧化中的活性中间体

光诱导的水分解反应是将可持续的阳光转化为化学能的一种有前途的方法。然而，传统金属催化剂驱动氧释放的高过电位限制了转化效率。等离子体金属-半导体系统可以潜在地解决该问题，因为局部表面等离子体激元共振产生的热电子会迅速注入半导体中，并且热空穴会集中以氧化水。这种等离激元诱导的水氧化的中间体和途径目前尚不清楚。在此，以Au的纳米结构的TiO ₂作为原型，我们在电化学电势研究水氧化中间体的不同的光谱特性接近TiO 2的平带电位₂使用原位电化学表面增强拉曼光谱。Au–O拉伸振动归因于pH值为0或13时的初始氧化态中间体Au（OH）₃和pH值为7时能量最高的中间体AuOOH。AuOOH的存在为加速四价氢的转化提供了第一个有力的实验证据。等离子体激元辅助水氧化的电子多步反应。