Lightly dispersed palladium: Catalysts made from atomically dispersed metal atoms on oxide supports can exhibit very high per atom activity. However, the low loadings needed to prevent metal particle formation can limit overall performance. Liu et al. stably decorated titanium oxide nanosheets with relatively high loadings of single palladium atoms by reducing the ions with ultraviolet light and ethylene glycol. These catalysts cleaved H ₂ into atoms and were highly effective for hydrogenating alkenes and aldehydes. Science , this issue p. 797

Plasmonic metal/semiconductor heterostructures show promise for visible-light-driven photocatalysis. Gold nanorods (AuNRs) semi-coated with TiO₂ are expected to be ideally structured systems for hydrogen evolution. Synthesizing such structures by wet-chemistry methods, however, has proved challenging. Here we report the bottom-up synthesis of AuNR/TiO₂ nanodumbbells (NDs) with spatially separated Au/TiO₂ regions, whose structures are governed by the NRs’ diameter, and the higher curvature and lower density of C_nTAB surfactant at the NRs’ tips than on their lateral surfaces, as well as the morphology’s dependence on concentration, and alkyl chain length of C_nTAB. The NDs show plasmon-enhanced H₂ evolution under visible and near-infrared light.