Enhancement of Photocatalysis by Dielectric Mie Resonances in a‐Se and a‐Se/Ag₂Se Core and Core‐Shell Nanoparticles

Submicron nanoparticles (NPs) of several semiconductors, such as Se or Te, exhibit pronounced dielectric Mie resonances in the visible range, which can be exploited for enhancing the efficiency of heterogeneous photocatalysis at the NP surface. Herein, it is demonstrated for the first time how dielectric Mie resonances in 190 nm amorphous a‐Se NPs and a‐Se/Ag 2 Se hetero‐NPs can enhance the efficiency of the model photocatalytic reactions involving organic (leuco‐methylene blue) and inorganic (K 4 [Fe(CN) 6 ]) redox‐active species. Formation of the local enhanced electromagnetic field near a‐Se NPs surface governs efficient photogeneration of e‐h pairs either in a‐Se core or Ag 2 Se shell. The photoredox activity of a‐Se NPs depends on many factors and can be altered via formation of the secondary semiconductor shell. Particularly, formation of several nm thick Ag 2 Se shell on the surface of a‐Se NPs increases photocatalytic activity governed by dielectric Mie resonances in a‐Se/Ag 2 Se core‐shell NPs as compared to bare a‐Se NPs. It is believed that submicron a‐Se/M x Se y ( M = Ag, Cu, etc.) core‐shell NPs can be a promising platform for advanced semiconductor photocatalysts with enhanced activity in vis–NIR range and tunable redox properties.