Decoupling the role of thermoplasmonics effect and hot electron injection of metallic nanoparticles in photoelectrochemical system

There has been an increasing interest in using thermoplasmonics effect of metallic nanoparticles to increase the rate of chemical reactions. However, it remains a challenge to separate out the role of thermoplasmonics effect from the localized surface plasmon resonance (LSPR). In this work, Au@SiO2/TiO2 with different SiO2 shell thicknesses (2, 3, 4, and 5 nm) are prepared as plasmonic composite photoanodes for photoelectrochemical (PEC) water splitting. Their electric and temperature field distributions are calculated by coupling the wave optics and the heat transfer modules in the COMSOL software. The decoupling of the LSPR relaxation mechanism of hot electron injection and thermoplasmonics effect is achieved by adjusting the SiO2 shell thickness. When the SiO2 thickness reaches 4 nm, the transmission process of the hot electrons produced by Au nanoparticles to TiO2 is completely hindered, and the thermoplasmonics effect is retained. By comparing the activities of Au@SiO2-4/ TiO2 with Au/TiO2, the relative contribution of thermoplasmonics effect can be estimated to be 36 % in PEC water splitting.