2-D Study of Near-field Generated by Surface Plasmon Resonance of Short Axis of Gold Nano-rods on SiO₂ and CeO₂/SiO₂ Substrates for Optimisation of Water Splitting Reaction

Abstract

Distinguishing near-field intensity distribution and plasmon resonance peak wavelength of surface plasmon resonance of gold nano-rods (AuNRs) can provide information for the optimisation of localised surface plasmon and gap plasmon resonances of gold nano-rods. This work, shows the influence of how refractive indexes of the surrounding medium and adjacent surface, as well as, AuNRs pair inter-particle gap contributes to the generation of surface plasmon resonances. The simulation model presented consists of AuNRs pair situated on silicon dioxide (SiO2) and cerium dioxide/silicon dioxide (CeO2/SiO2) substrates with air and water as the surrounding media. The results show high near-field intensities at AuNRs/CeO2 interfaces with CeO2 refractive index (n = 2.38), and the near-field intensities contributed by the gap resonance is minimal between the AuNRs of inter-particle gap of 10 nm, however, the near-field intensities become significant near to the AuNRs/CeO2 interfaces because of reduced near-field interference. The simulation set-up provides the conditions for water splitting in thermochemical redox reaction of CeO2/CeO2-x resulting in the production of hydrogen. AuNRs pair with inter-particle gap of 5 nm situated on 10 nm thick CeO2 of CeO2/SiO2 substrate shows the most favorable conditions for water splitting.