(Invited) Nanoscale Design and Modification of Plasmonic Aerogels for Photocatalytic Hydrogen Generation

Abstract

Composite catalytic aerogels comprise a highly-flexible design motif for the creation of solar fuels photocatalysts. We exploit the compositional and interfacial design flexibility of catalytic aerogels to couple surface plasmon resonant (SPR) guests to nanometric oxidation and reduction catalysts in one hierarchical photocatalytic composite architecture. In our composite aerogels, the nanoscale TiO2 aerogel acts as a 3D-interconnected network of nanowires that couples all of the functional elements required to photogenerate molecular hydrogen from visible light and water: visible light sensitization, electron and ion transport, and oxidation and reduction catalysis. We investigate the effects of synthetically modifying the TiO2 aerogel network and the nanoparticulate Au||TiO2 interfaces in plasmonic Au–TiO2 aerogels on light sensitization, carrier (electron–hole pair) generation, and photocatalytic H2 evolution under both broadband (i.e., UV + visible) and visible excitation. We also introduce oxidation and reduction co-catalyst nanoparticles into the plasmonic aerogels, creating composite aerogels that perform visible light SPR–driven photocatalytic reduction of water to generate H2. The nanostructured high surface–area network in the aerogel spatially and effectively separates charge while electrochemically connecting plasmonic nanoparticle sensitizers and metal nanoparticle all in one mesoscale architecture and at length scales compatible with the kinetics of each reaction. Reference: "Plasmonic aerogels as a 3D nanoscale platform for solar fuels photocatalysis.” P. A. DeSario, J. J. Pietron, A. Dunkelburger, T.H. Brintlinger, O. Baturina, R. M. Stroud, J. C. Owrutsky, and D. R. Rolison, Langmuir, 2017, 33, 9444–9454; doi: 10.1021/acs.langmuir.7b01117 This work is supported by the U.S. Office of Naval Research.