Realization of a Photoelectrochemical Cascade for the Generation of Methanol: A Liquid Solar Fuel.

Biochemical networks use reaction cascades to selectively reduce CO using energy from sunlight, but can similar selectivity be achieved by applying a cascade approach to an engineered system? Here, we report the design and implementation of a two-step photoelectrochemical (PEC) cascade to a liquid solar fuel: reduction of CO to CO and subsequent reduction of CO to methanol. The potentials required to perform the reductions were generated using custom-made III-V-based three-terminal tandem (3TT) solar cells. Cobalt phthalocyanine immobilized on multiwalled carbon nanotubes (CoPc/MWCNT) catalyzed both reactions.