Tuning Light-Driven Propane Dehydrogenation Pathways via Dopant Identity in a Dilute Plasmonic Copper-Based Alloy

Dopant identity in metal alloys provides a powerful handle to tune catalytic mechanisms, yet its role in modifying photocatalytic pathways in reactions such as nonoxidative propane dehydrogenation (PDH) remains poorly understood. Here, we investigate dilute CuRh alloys to determine whether rhodium dopants favor hot-carrier or photothermal pathways under illumination. Kinetic measurements show that CuRh operates via a photothermal mechanism: the apparent activation energy remains nearly unchanged between light and dark conditions, while reaction rates increase exponentially with light power density. Real-time time-dependent density functional theory confirms the absence of persistent charge transfer from CuRh to propane, in contrast to the hot-carrier behavior previously observed in CuPt alloys. Extended illumination does not measurably affect coking or sintering in CuRh, indicating that localized photothermal heating has a minimal impact on catalyst stability. These findings demonstrate that dopant identity governs the dissipation of plasmonic energy in dilute alloys and provide design principles for light-assisted alkane dehydrogenation and other photothermal catalytic transformations.