Gradient Plasmonic Nanogap Homojunctions for Hot-Electron-Driven Photocatalysis

High Resolution Image Download MS PowerPoint Slide Hot electrons (HEs) can help realize chemical reactions that are unachievable by traditional methods, but HE-based chemistry is limited by the low yield and limited scalability of suitable hot-electron sources. We here demonstrate the potential of plasmonic homojunctions, interfaces between plasmonic structures with identical composition but varying electronic properties, to extract HEs with high efficiency and scalability. By engineering the emergence of morphological ordering in top-down fabricated gradient assemblies, a novel plasmonic interaction effect between neighboring particles was achieved. This plasmonic hybridization and the formation of a strong internal electric field facilitate efficient interfacial transfer of HEs. Characterization through ultrafast pump–probe and local photocurrent measurements reveals a 2-fold enhancement in hot electron lifetime and in external quantum efficiency. Our plasmonic homojunctions are applied to photocatalytic CO 2 conversion, outperforming previous approaches with an unprecedented CO product yield of 394.5 μmol g –1 h –1 and near-unity selectivity.