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首页> 外文期刊>Advanced Functional Materials >A Cocatalytic Electron-Transfer Cascade Site-Selectively Placed on TiO2 Nanotubes Yields Enhanced Photocatalytic H-2 Evolution
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A Cocatalytic Electron-Transfer Cascade Site-Selectively Placed on TiO2 Nanotubes Yields Enhanced Photocatalytic H-2 Evolution

机译：选择性地放置在TiO2纳米管上的共催化电子转移级联产生增强的光催化H-2演化

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摘要

Separation and transfer of photogenerated charge carriers are key elements in designing photocatalysts. TiO2 in numerous geometries has been for many years the most studied photocatalyst. To overcome kinetic limitations and achieve swift charge transfer, TiO2 has been widely investigated with cocatalysts that are commonly randomly placed nanoparticles on a TiO2 surface. The poor control over cocatalyst placement in powder technology approaches can drastically hamper the photocatalytic efficiencies. Here in contrast it is shown that the site-selective placement of suitable charge-separation and charge-transfer cocatalysts on a defined TiO2 nanotube morphology can provide an enhancement of the photocatalytic reactivity. A TiO2-WO3-Au electron-transfer cascade photocatalyst is designed with nanoscale precision for H-2 production on TiO2 nanotube arrays. Key aspects in the construction are the placement of the WO3/Au element at the nanotube top by site-selective deposition and self-ordered thermal dewetting of Au. In the ideal configuration, WO3 acts as a buffer layer for TiO2 conduction band electrons, allowing for their efficient transfer to the Au nanoparticles and then to a suitable environment for H-2 generation, while TiO2 holes due to intrinsic upward band bending in the nanotube walls and short diffusion length undergo a facilitated transfer to the electrolyte where oxidation of hole-scavenger molecules takes place. These photocatalytic structures can achieve H-2 generation rates significantly higher than any individual cocatalyst-TiO2 combination, including a classic noble metal-TiO2 configuration.
机译：光生载流子的分离和转移是设计光催化剂的关键要素。多年来，在许多几何形状中的TiO2一直是研究最多的光催化剂。为了克服动力学限制并实现快速的电荷转移，已经广泛地使用助催化剂对TiO2进行了研究，助催化剂通常是将纳米颗粒随机放置在TiO2表面上。在粉末技术方法中对助催化剂放置的控制不力会严重阻碍光催化效率。相比之下，这里显示出合适的电荷分离和电荷转移助催化剂在确定的TiO2纳米管形态上的位点选择性放置可以提高光催化反应活性。设计了具有纳米级精度的TiO2-WO3-Au电子转移级联光催化剂，用于在TiO2纳米管阵列上生产H-2。构造中的关键方面是通过定点沉积和Au的自序热去湿将WO3 / Au元素放置在纳米管顶部。在理想的配置中，WO3充当TiO2导带电子的缓冲层，使其有效转移至Au纳米粒子，然后转移至H-2生成的合适环境，而TiO2则由于纳米管中固有的向上能带弯曲而产生孔壁和短扩散长度易于转移到电解质中，在该电解质中发生空穴清除剂分子的氧化。这些光催化结构可实现的H-2生成速率明显高于任何单独的助催化剂-TiO2组合，包括经典的贵金属-TiO2构型。

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