Surface plasmon-enhanced gas sensing in single gold-peapodded silica nanowires

• Published in: NPG Asia materials Vol. 5; no. 5; p. e49
• Main Authors: Wang, Sheng-Bo, Huang, Yi-Fan, Chattopadhyay, Surojit, Jinn Chang, Shoou, Chen, Ruei-San, Chong, Cheong-Wei, Hu, Ming-Shien, Chen, Li-Chyong, Chen, Kuei-Hsien
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2013; Nature Publishing Group
• Subjects: 639/301/1005/1009; 639/301/357/1016; 639/925/927/1021; Biomaterials; Chemistry and Materials Science; Energy Systems; Materials Science; Optical and Electronic Materials; original-article; Structural Materials; Surface and Interface Science; Thin Films; gas sensor; silica; nanowire; surface plasmon
• ISSN: 1884-4049; 1884-4057
• DOI: 10.1038/am.2013.17

An intriguing system featuring a wide band gap silica nanowire (SiO x NW) that absorbs visible light (532 nm) via the surface plasmons (SPs) of embedded gold nanoparticles (Au NPs) is reported for sensing applications. We report SP resonance-enhanced molecular oxygen sensing by single Au-NPs@SiO x NWs under 532-nm illumination (visible light) at room temperature. Excellent selectivity of the Au-NPs@SiO x NWs to molecular oxygen in air has been demonstrated. Illumination improved the sensing properties in terms of response and fast recovery time, which can be attributed to the photogenerated hole-mediated oxygen desorption. A general strategy of light-modulated sensing, vis-à-vis dark, is demonstrated in a wide band gap single NW system that could potentially open up routes for biosensing, because silica and Au both lack biotoxicity. Gas sensing: Peas in a pod A Taiwan-based team led by Kuei-Hsien Chen has improved the room-temperature gas-sensing properties of silica nanowire-based systems by incorporating gold nanoparticles inside the nanowire in a ‘peas-in-a-pod’ manner. Upon shining light on the device, surface plasmon resonance occurs at gold nanoparticles that absorb the visible light (from a 532 nm laser) at room temperature. Under this irradiation, a gold-embedded silica nanowire undergoes photogeneration of electrons and holes at a higher rate than its plain silica counterpart. As a result, the nanowire's conductivity is enhanced and the sensing of oxygen at the wire's surface is facilitated by the molecule's interaction with photogenerated electrons, while its recovery (desorption) is improved by the presence of the holes. As neither gold nor silica nanoparticles are known to be toxic, the gold-silica nanowire system holds promise for measuring oxygen in biological and medical applications. The gas-sensing performances of the Au NP-embedded silica nanowire can be enhanced by visible light (532 nm) illumination at room temperature, which improves not only sensing response but also recover time.