Enhancing Solar Water Splitting of Textured BiVO₄by Dual Effect of a Plasmonic Silver Nanoshell: Plasmon-Induced Light Absorption and Enhanced Hole Transport

Herein, we demonstrate high-efficiency photoelectrochemical (PEC) water oxidation by combining a textured BiVO4 (t-BVO) photoanode with double-deck structured SiO2@Ag nanoparticles (NPs) with a Ag nanoshell. The SiO2@Ag NPs, composed of a SiO2 core with a diameter of ∼90 nm and a Ag shell with a thickness of ∼20 nm, induce the strong localized surface plasmon resonance (LSPR). This LSPR effect amplifies the electric fields on the near surface of t-BVO, resulting in efficient light harvesting and charge separation performance. Furthermore, the direct contact of the Ag shell with the surface of t-BVO promotes the efficient charge transfer and subsequent water oxidation under visible light. Consequently, the high photocurrent density values of 5.8 mA/cm2 for SiO2@Ag/t-BVO photoanodes at 1.23 V versus a reversible hydrogen electrode are obtained, which is 49% improvement compared to the pristine t-BVO photoanode (3.9 mA/cm2). The effect of plasmonic nanoparticles on the PEC of t-BVO is explained from the viewpoint of the light confinement (near-field effect), the plasma-induced energy transfer, and the improved catalytic efficiency. Building up such a synergistic nanostructured photoelectrode system is a promising approach for achieving high efficiency in PEC water splitting.