Plasmonic Active "Hot Spots"-Confined Photocatalytic CO 2 Reduction with High Selectivity for CH 4 Production.

Plasmonic nanostructures have tremendous potential to be applied in photocatalytic CO 2 reduction, since their localized surface plasmon resonance can collect low-energy-photons to derive energetic "hot electrons" for reducing the CO 2 activation-barrier. However, the hot electron-driven CO 2 reduction is usually limited by poor efficiency and low selectivity for producing kinetically unfavorable hydrocarbons. Here, a new idea of plasmonic active "hot spot"-confined photocatalysis is proposed to overcome this drawback. W 18 O 49 nanowires on the outer surface of Au nanoparticles-embedded TiO 2 electrospun nanofibers are assembled to obtain lots of Au/TiO 2 /W 18 O 49 sandwich-like substructures in the formed plasmonic heterostructure. The short distance (< 10 nm) between Au and adjacent W 18 O 49 can induce an intense plasmon-coupling to form the active "hot spots" in the substructures. These active "hot spots" are capable of not only gathering the incident light to enhance "hot electrons" generation and migration, but also capturing protons and CO through the dual-hetero-active-sites (Au-O-Ti and W-O-Ti) at the Au/TiO 2 /W 18 O 49 interface, as evidenced by systematic experiments and simulation analyses. Thus, during photocatalytic CO 2 reduction at 43± 2 °C, these active "hot spots" enriched in the well-designed Au/TiO 2 /W 18 O 49 plasmonic heterostructure can synergistically confine the hot-electron, proton, and CO intermediates for resulting in the CH 4 and CO production-rates at ≈35.55 and ≈2.57 µmol g -1 h -1 , respectively, and the CH 4 -product selectivity at ≈93.3%.