Photochemical deposition of cobalt-based oxygen evolving catalyst on a semiconductor photoanode for solar oxygen production
Photochemical deposition of cobalt-based oxygen evolving catalyst on a semiconductor photoanode for solar oxygen production
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DOI：
10.1073/pnas.0910203106
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发表时间：
2009-12-08
影响因子：
11.1
通讯作者：
Choi, Kyoung-Shin
中科院分区：
文献类型：
--
作者：
Steinmiller, Ellen M. P.;Choi, Kyoung-Shin
本研究描述了用于太阳能析氧的半导体光阳极上的钴基析氧催化剂的光化学沉积。在光沉积过程中，在照射时在半导体中产生电子-空穴对，并且光生空穴用于将Co2+离子氧化成Co 3+离子，导致基于Co 3+的催化剂沉淀在半导体表面上。催化剂的光沉积和太阳光释放O-2都是利用光生空穴的光氧化反应。因此，光沉积提供了一种将析氧催化剂与光阳极偶联的有效方式，其通过将催化剂自然地放置在空穴最容易用于太阳能O-2析出的位置处。在这项研究中，钴基催化剂的光化学沉积为10-30 nm的纳米粒子的ZnO表面上。的ZnO电极的光电流-电压特性与不存在的Co基催化剂的比较表明，催化剂通常增强了ZnO电极的阳极光电流，其效果更显着时，带弯曲是不太显着。在ZnO光阳极上的Co基催化剂的存在下，光电流的起始电势也向负方向移动了0.23 V，更接近平带电势。这些结果表明，钴基催化剂可以有效地利用ZnO中的光生空穴来增强太阳能O-2的释放。在这项研究中所描述的光沉积方法可以被用作一般的路线，存款的钴基催化剂上的任何半导体电极的价带边缘位于一个更积极的电位比钴离子的氧化电位。
This study describes the photochemical deposition of Co-based oxygen evolution catalysts on a semiconductor photoanode for use in solar oxygen evolution. In the photodeposition process, electron-hole pairs are generated in a semiconductor upon illumination and the photogenerated holes are used to oxidize Co2+ ions to Co3+ ions, resulting in the precipitation of Co3+-based catalysts on the semiconductor surface. Both photodeposition of the catalyst and solar O-2 evolution are photo-oxidation reactions using the photogenerated holes. Therefore, photodeposition provides an efficient way to couple oxygen evolution catalysts with photoanodes by naturally placing catalysts at the locations where the holes are most readily available for solar O-2 evolution. In this study Co-based catalysts were photochemically deposited as 10-30 nm nanoparticles on the ZnO surface. The comparison of the photocurrent-voltage characteristics of the ZnO electrodes with and without the presence of the Co-based catalyst demonstrated that the catalyst generally enhanced the anodic photocurrent of the ZnO electrode with its effect more pronounced when the band bending is less significant. The presence of Co-based catalyst on the ZnO photoanode also shifted the onset potential of the photocurrent by 0.23 V to the negative direction, closer to the flat band potential. These results demonstrated that the cobalt-based catalyst can efficiently use the photogenerated holes in ZnO to enhance solar O-2 evolution. The photodeposition method described in this study can be used as a general route to deposit the Co-based catalysts on any semiconductor electrode with a valence band edge located at a more positive potential than the oxidation potential of Co2+ ions.