Plasmon-Enhanced Layered Double Hydroxide Composite BiVO4 Photoanodes: Layering-Dependent Modulation of the Water-Oxidation Reaction

Photo-electrochemical (PEC) generation of hydrogen from sunlight and water is a promising pathway to carbon-neutral energy. We describe a highly efficient three-layer photoanode, which consists of plasmonic Au-SiO2 core–shell nanoparticles (Au@SiO2 NPs), a layered double hydroxide (LDH), and semiconducting BiVO4. To understand the spatial dependence of water oxidation by the composite photoanode, we examined two configurations, LDH/Au@SiO2/BiVO4 (photoanode I) and Au@SiO2/LDH/BiVO4 (photoanode II), which differed in the order in which the LDH nanosheets and Au@SiO2 layers were grown on BiVO4. In a PEC water-splitting cell under back-side illumination, at E0′(H2O/O2) = 1.23 V versus RHE, the photocurrent density of photoanode I reached 1.92 mA·cm–2, showing a 52% increase compared to that of photoanode II; the efficiency toward water oxidation of photoanode I was 69%, 1.3 times higher than that of photoanode II. This is because light absorption by Au@SiO2 in photoanode I excites a strong localized surface ...