Effect of plasmonic gold nanoparticles morphology and silica layer on efficient light induced carbon dioxide photo-conversion to formic acid in whole solar spectrum region

Plasmonic nanoparticles have unique optical properties such as scattering, absorption, enhanced electro-magnetic field, fluorescence quenching, and hot-electron generation because of the localized surface plasmon resonance... [ view full abstract ]

Plasmonic nanoparticles have unique optical properties such as scattering, absorption, enhanced electro-magnetic field, fluorescence quenching, and hot-electron generation because of the localized surface plasmon resonance [1]. These properties were extensively explored for their use in numerous photochemical and biological applications.

Here, we have highlighted the preparation of silica coated plasmonic hybrid gold nanoparticles with different morphologies and their application for light induced photoreduction of carbon dioxide to formic acid. We have used Xe lamp (visible light), NIR laser and solar simulator as the light source in order to examine the feasibility of using whole solar spectrum region for carbon dixode photoconversion. Silica coated gold nanorods (AuNR), nanostars (AuNS) and spherical nanoparticles (AuNP) were prepared by utilizing simple solution-based synthetic strategies. The hot electron generation, which is excited plasmon with higher energy than fermi-level after light absorption in the nanostructures and LSPR excitation, is useful to increase the catalytic activity of plasmonic nanomaterials efficiently [2]. Silica coated AuNS, AuNP and AuNR have shown chemical yield of 1.14%, 0.92% and 0.44% in visible light, 0.3%, 0.2% and 0.64% in NIR light and 0.22%, 0.15% and 0.11% in sun light for formic acid formation when irradiated for 5 h, respectively. Silica coated AuNS shown better efficiency in visible light irradiation and there was more than 100 fold increases in the conversion efficiency after AuNS coated with silica. Surface plasmon resonance band and efficient water oxidation ability of silica layer played vital role in the conversion efficiency of CO₂ to HCOOH.

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