We describe the incorporation of plasmonic copper (Cu) nanoparticles in titania (TiO2) aerogels and demonstrate surface plasmon resonance (SPR)–driven photochemistry as well as small molecule oxidation. Copper is appealing as a more abundant, less expensive alternative to precious metals for plasmonic and catalytic applications, however, the ease with which Cu to oxidizes at the expense of its plasmonic character greatly limits its potential applications. Whereas most reports of supported, plasmonic Cu nanoparticles describe the necessity of preventing Cu oxidation by relying on surface-obscuring chemical stabilizers, we demonstrate that plasmonic properties of Cu can be preserved by offering an extended interfacial contact with a reducing metal oxide support – an interfacial design motif characteristic of aerogels. The extended three dimenstional interface between photodeposited 2–3 nm Cu nanoparticles and the networked ~10 nm TiO2 particulates of the aerogel support preserves plasmonic behavior of Cu nanoparticles even after long-term exposure to ambient air. In contrast, plasmonic behavior is not seen for Cu photodeposited at a non-networked TiO2 nanopowder in which the primary particle size is ~10× greater than the size of the supported Cu particle and the interface is limited to a single one dimensional junction. The wavelength dependence of photoelectrochemical methanol oxidation at Cu/TiO2 aerogel photoanodes verifies the plasmonic origin of the photoelectrochemistry. Small molecule oxidation reactions dependent upon Cu oxidation state are characterized at the composite catalysts.

Oxidation-stable plasmonic copper nanoparticles in catalytic TiO2 aerogels

255th National Meeting (2018)

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