Plasmonic enhancement of the optical absorption and catalytic efficiency of BiVO4 photoanodes decorated with Ag@SiO2 core–shell nanoparticles

Abstract

Recent progress in the development of bismuth vanadate (BiVO₄) photoanodes has firmly established it as a promising material for solar water splitting applications. Performance limitations due to intrinsically poor catalytic activity and slow electron transport have been successfully addressed through the application of water oxidation co-catalysts and novel doping strategies. The next bottleneck to tackle is the modest optical absorption in BiVO₄, particularly close to its absorption edge of 2.4 eV. Here, we explore the modification of the BiVO₄ surface with Ag@SiO₂ core–shell plasmonic nanoparticles. A photocurrent enhancement by a factor of ∼2.5 is found under 1 sun illumination (AM1.5). We show that this enhancement consists of two contributions: optical absorption and catalysis. The optical absorption enhancement is induced by the excitation of localized surface plasmon resonances in the Ag nanoparticles, and agrees well with our full-field electromagnetic simulations. Far-field effects (scattering) are found to be dominant, with a smaller contribution from near-field plasmonic enhancement. In addition, a significant catalytic enhancement is observed, which is tentatively attributed to the electrocatalytic activity of the Ag@SiO₂ nanoparticles.