Enhanced Production of Solar-Fuels By Plasmonic Metal/Semiconductor Photocatalyst Heterostructures

Earth’s dependence on fossil fuels for providing the majority of the world’s energy is problematic due to the finite nature of fossil fuels and the release of greenhouse gases and other pollutants during their combustion. As such, sustainable, carbon-neutral fuels are needed as a long-term replacement for fossil fuels. One promising approach is direct solar energy-to-chemical fuel conversion by photocatalysis. Examples of fuels produced include H₂ from photocatalytic water splitting or photocatalytic reduction of CO₂ to methanol or methane. However, current photocatalyst materials suffer from a combination of problems such as poor charge carrier lifetimes and mobility, poor photostability in water, wide bandgaps that allow only UV light absorption, and/or an inactive surface for carrying out redox reactions. Forming heterostructures made of plasmonic metals (i.e. Au, Ag, or Cu) and semiconductor photocatalyst materials can serve to enhance overall photocatalytic performance versus the photocatalyst alone. This enhancement comes from photonic mechanisms like visible or NIR light absorption or scattering by plasmonic metal nanostructures and plasmonic enhancement mechanisms of direct transfer of “hot” electrons from the plasmonic metal to the photocatalyst and plasmon-induced resonant energy transfer from plasmonic metal to photocatalyst through dipole-dipole interactions. This poster summarizes our latest research on determining the nature of these enhancement mechanisms and progress towards high efficiency photocatalytic production of solar-fuels.