Photo-excited electroless deposition of semiconducting oxide thin films and their electrocatalytic properties
Photo-excited electroless deposition of semiconducting oxide thin films and their electrocatalytic properties
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DOI：
10.1039/c0jm03577g
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发表时间：
2011-03
影响因子：
--
通讯作者：
K. Kamada;Ayano Moriyasu
中科院分区：
文献类型：
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作者：
K. Kamada;Ayano Moriyasu
本文研究了紫外光照射对从水溶液中化学沉积几种n型半导体氧化物薄膜的有利影响。为了得到CeO2，Ce3+在溶解氧分子存在下被氧化到较高的价态，然后通过局部电池机制以CeO2的形式沉淀在导电衬底上。在反应过程中用紫外光照射衬底会在表面氧化层中产生光载流子(电子和空穴)。由此得到的光载流子能够在预沉积的CeO2核表面和衬底表面发生进一步的电化学反应。结果表明，紫外光照射显著提高了薄膜的沉积速度和结晶度。在铂衬底上制备的CeO2薄膜显示出对甲醇氧化的电催化活性，而不需要后退火，而在黑暗中沉积的薄膜具有较低的活性。根据薄膜的形貌和结晶度对这种差异进行了讨论。此外，还证实了光照射也加速了锡和氢氧化物的化学沉积。本文详细讨论了光化学沉积的机理，并阐明了所提出的技术的优点。
The present study demonstrates the beneficial effects of ultraviolet (UV) light irradiation on the electroless deposition of several n-type semiconducting oxide thin films from an aqueous solution. To obtain ceria (CeO2), Ce3+ was oxidized to a higher valence in the presence of dissolved oxygen molecules and was then precipitated as CeO2 on a conductive substrate through a local cell mechanism. Irradiation of the substrate by UV light during the reaction caused the generation of photocarriers (electron and holes) in the surface oxide layer. The resultant photocarriers enabled further electrochemical reactions on the surfaces of the pre-deposited CeO2 nuclei together with the substrate surface. As a result, the deposition rate and crystallinity of the film were significantly improved by UV light irradiation. CeO2 thin films prepared on a Pt substrate by the proposed photoelectroless deposition method showed electrocatalytic activity for methanol oxidation without post-annealing, in contrast to the lower activity of a film deposited in the dark. This discrepancy is discussed on the basis of film morphology and crystallinity. Furthermore, it was confirmed that the electroless deposition of Sn and Pr oxide (hydroxide) was also accelerated by photoirradiation. In this paper, the photoelectroless deposition mechanism is discussed in detail, and the advantages of the proposed techniques are clarified.