Abstract
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 fluoride assisted galvanic replacement reaction was developed to prepare three-dimensional Ag, Pt－Ag, and Au DNFs under ambient conditions. The material characteristics and photo-enhancement toward methanol oxidation reaction were studied. In the Ag and Pt－Ag DNFs, visible- light enhanced methanol oxidation reaction was preliminarily verified. In the Au DNFs, 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 wavelength- dependent enhancement. Moreover, the cost-effective and facile process suitable for room-temperature preparation of Si-based metal DNFs provides a new direction for preparing large-scale free-standing metallic nanostructures.