IR-Driven strong plasmonic-coupling on Ag nanorices/W18O49 nanowires heterostructures for photo/thermal synergistic enhancement of H2 evolution from ammonia borane

Abstract

Plasmonic coupling between two or more metal nanostructures has attracted significant interest, since this fascinating near-field interaction is more effective for the aggregation/magnification of the incident light intensity compared to normal surface-plasmon-resonance (SPR) of single nanostructures. Herein, we report, for the first time, an IR-driven strong plasmonic coupling in an unusual metal/non-metal heterostructure system. This system is fabricated through random assemblage of Ag nanorices (NRs) onto W18O49 nanowires (NWs) film with F-doped SnO2 glass as substrate. Through the 3D-finite element simulation, we demonstrate that the plasmonic coupling between Ag NRs and W18O49 NWs significantly enhances the localized electric fields at the “hot spots”. This achieved magnitudes of 101-104 times of that of incident light, thus leading to the promoted generation of plasmonic “hot-electrons”. Moreover, the resonance excitation of plasmonic coupling on the heterostructures not only induces ultrafast electron transfer from W18O49 to Ag hetero-components, but also the photothermal effect to increase the localized temperature. Upon SPR-coupling excitation, the Ag/W18O49 heterostructures film exhibits a remarkable enhancement of the photo/thermal catalytic activity for H2 evolution from ammonia borane compared to that of either the Ag NRs (˜8.2 ×) or W18O49 NWs (˜9.0 ×) films. Notably, we observed an obvious H2 evolution over the Ag/W18O49 heterostructures film under natural sunlight irradiation.