Self-assembled Plasmonic nanoOptics for sustainable Chemistry

The energy sector currently accounts for 55% of anthropomorphic greenhouse gas (GHG) emissions, and while concerted efforts are employed to introduce renewables, the inability of solar cells, wind turbines and bioenergy to produce fuels limits the growth of their contribution beyond 10%. The remaining 45% of anthropomorphic GHG emissions are linked to industrial scale goods production and agriculture. These sectors are essential for our current way of life and allow us to sustain an ever-growing population. Yet despite an impending climate crisis, these industries still have to predominantly rely on fossil fuels as transitions to sustainable alternatives have proven challenging.

These problems are further exacerbated by our current linear 'take-make-waste' model of resource utilisation, with many products being used once and promptly disposed of. The resulting waste is either incinerated, contributing to GHG emissions, or piles up in landfills or our oceans. Therefore, these sectors (Energy, Production, Agriculture) require immediate and disruptive innovations to curb ballooning contributions to climate change. For a sustainable future, it is imperative we learn how to efficiently use resources which are abundant and replenish in our direct environments such as bio-waste from food production, plastic, CO2, water, and sunlight. To this end, many photocatalytic technologies are being developed which, if successful, would be truly transformative as they would allow us to use sunlight to turn otherwise unwanted waste into fuels and useful valorised organics. But for such artificial photosynthesis to be successful, there are three major properties of catalysts that need to be improved:
1. Photon efficiency with respect to the solar spectrum.
2. Catalytic activity: the rate at which a catalyst converts a feedstock.
3. Catalytic selectivity: the effectiveness of a catalyst in producing only the desired product.

To address these issues, this proposal aims to employ plasmonic nanoreactors, formed by self-assembling faceted metal nanoparticles to create a narrow (~1nm) inter-particle separation. The narrow gaps enable optical coupling between the nanoparticles, forming intense plasmonic hotspots which can be employed, using molecular catalysts, for enhanced plasmon assisted catalysis whilst allowing reactants and products to flow in and out of the nanogap, forming a nanoscale photocatalytic flow-reactor.