(83a) Single-Atom Plasmonic Alloys for Alkane Dehydroaromatization with Visible Light

Developing materials that convert visible light into chemical energy is essential for enabling low-carbon pathways in producing fuels and commodity chemicals. This presentation will dilute copper–platinum (CuPt) plasmonic alloy catalysts in which platinum atoms are dispersed within a copper nanoparticle host at the single-atom level. These materials exhibit significantly enhanced activity for nonoxidative propane dehydrogenation (PDH) and alkane dehydroaromatization when illuminated at the localized surface plasmon resonance (LSPR) of Cu (~585 nm) and effectively coupling photonic excitation into chemical transformation.

Through operando spectroscopy, kinetic analysis, and isotope labeling, we demonstrate that single-atom Pt dopants (CuPtSA) are preferential localization sites for plasmon-generated hot holes. These energetic carriers facilitate C–H bond activation—the rate-limiting step in PDH—resulting in propylene formation rates that are substantially higher under illumination compared to dark conditions. Once the olefin is formed, the Cu host can perform a bimolecular cyclization to form benzene and other aromatics. By systematically increasing the degree of hydrocarbon saturation for C₃ (i.e., propane, propylene, propyne) and C₂ (ethane, ethylene, acetylene) reactants in the feed, we demonstrate that plasmon-driven aromatization of unsaturated hydrocarbon is a generalized phenomenon on copper nanoparticle surfaces. In mixed alkane feeds (i.e., a co-flow of propane and butane), we demonstrate light-enhanced photosynthetic formation of toluene and xylenes over CuPt single-atom alloys. This work demonstrates the significance of bifunctional photocatalyst design where dual chemical functions of C-H activation (on isolated Pt sites) and aromatization (on the Cu host) can work together for designer outcomes, and the design principles established here are broadly applicable to the development of materials for photocatalytic energy generation and commodity chemicals.