Floatable carbon nitride-plastic composite for paired photocatalysis at the liquid-liquid interface

Floatable photocatalysts have been demonstrated for solar fuel synthesis at the gas-liquid interface but not yet between immiscible solvents for chemical synthesis. Here, we introduce a carbon nitride and low-density plastics composite with tunable density, produced by a sustainable fabrication process for applications in liquid-liquid photocatalysis. This material enables 2D confinement, catalyst recovery, and paired, compartmentalized photocatalysis. Carbon nitride-polypropylene at the 1-butanol|water interface produced 2.7 ± 0.5 mmol L −1 h −1 aqueous H 2 O 2 from O 2 reduction and 1.5 ± 0.4 mmol L −1 h −1 butanal from butanol oxidation at room temperature (λ = 450 nm, 40 mW cm −2 ). Replacing 1-butanol with kraft lignin in ethyl acetate resulted in integrated H 2 O 2 synthesis (0.78 ± 0.01 mmol L −1 h −1 ) and organo-soluble biomass upcycling (0.67 ± 0.01 of veratraldehyde from a model compound). Continuous processing of simultaneously produced H 2 O 2 and valorized lignin was achieved by developing a flow reactor platform utilizing concentrated simulated solar light.