光增強甲醇氧化反應為近年來光－燃料電池的重要研究課題。先前技術對於光增強甲醇氧化反應觸媒的研 究多聚焦於金屬－半導體複合材料。本研究提出利用三維金奈米樹枝晶叢林做為光電極，在可見光照射下 增強甲醇氧化反應。此純金屬奈米結構同時具有觸媒及光觸媒之功效。本研究使用氟離子輔助加凡尼取代 反應 (fl uoride assisted galvanic replacement reaction)，於室溫條件下，在矽 (Si) 基材上快速成長了三維金奈 米樹枝晶叢林結構，同時研究其材料特性及光觸媒效果。在 Au 奈米樹枝晶上，甲醇氧化電流在寬頻可見 光照射下 (69 mW·cm-2；λ> 400 nm) 提升了 28%。我們更進一步比較了不同波長入射光對於甲醇氧化電 流增強效果之差異，並且引入局部表面電漿子共振 (localized surface plasmon resonance) 模型解釋此隨波長 改變的光增強現象。此外，本研究提出的低成本、快速且可室溫操作的矽基金屬奈米樹枝晶製造方法，也 為未來製造大面積自站立三維金屬奈米結構提供了新的思維方向。

Photo-enhanced methanol oxidation reaction (PEMOR) is a crucial issue in the development of photo-fuel cells. In the study of catalysts for the PEMOR, efforts have been focused on metal-semiconductor composites in the prior arts. In this study, we utilized metal dendritic nanoforests (DNFs) as the photo-elecrodes to boost methanol oxidation reaction under irradiation. These pure metallic nanostructures can serve as catalysts and photo-catalysts simultaneously. Besides, a facile fl uoride assisted galvanic replacement reaction was developed to prepare threedimensional Au DNFs under ambient conditions. The material characteristics and photo-enhancement toward methanol oxidation reaction were studied. The oxidation current of methanol was boosted by 28% under broadband visible light illumination (69 mW－cm-2；λ＞ 400 nm) .We further compared the photo-enhancements under various irradiation wavelengths. Localized surface plasmon resonance was introduced to explain the wavelengthdependent enhancement. Moreover, the cost-effective and facile process suitable for room-temperature preparation of Si-based metallic DNFs provides a new direction for preparing large-scale free-standing metallic nanostructures.