domino4chem: Semi-biological Domino Catalysis for Solar Chemical Synthesis

Mitigating CO2 emissions and transitioning to a circular economy are urgent actions to safeguard our prosperous future. Carbon capture and utilisation is a carbon-neutral process to recycle CO2 for the synthesis of valuable molecules and materials powered by renewable energy. The synthesis of fuels from CO2 using sunlight has made significant advances, but major challenges remain: (i) Synthetic approaches using semiconductors are highly efficient in light utilisation but can only produce the simplest of products from CO2; (ii) biological approaches can generate more complex products but are slow in CO2 uptake and inefficient in their use of solar energy.

This proposal will pioneer the controlled synthesis of complex chemicals at high efficiency using sunlight by combining the strength of synthetic and biological technologies. An integrated platform will be developed that incorporates efficient light harvesting by semiconductors to drive a network of synthetic and biological catalysts to convert CO2 to bespoke complex chemical products. Specifically, photoelectrochemical tandem devices and photocatalyst powder sheets will be employed as the light harvesting component. These will drive a series of (bio)catalysts integrated in a bespoke porous architecture to catalyse compartmentalised reactions in sequence ('domino catalysis'). Synthetic catalysts will first reduce CO2 to vectors such as formate and CO with electrons being sourced from the oxidation of water to O2. The vectors will subsequently be used in the same device as feedstocks for microorganisms or enzyme/synthetic cascades to produce the target chemical. This vector-approach enables the efficient use of a wide range of catalysts, including engineered metabolic pathways, to synthesise desired products with a high degree of control.

The proposed direct photon-to-chemical conversion technology will provide a general biohybrid platform to synthesise high value chemicals sustainably from sunlight in the future.