Nitrogen-defective carbon nitride nanorod arrays for continuous-flow photosynthesis of H₂O₂

The surface activity and continuous photosynthesis with easy product separation are two main concerns for practical H₂O₂ photogeneration which calls for integration of efficient photocatalyst with specifically designed reactor. Taking advantage of the intrinsic superior charge separation and electron transfer of the one-dimensional CN, herein, N-vacancy abundant carbon nitride nanorod arrays (CNNRs) were demonstrated as an efficient photocatalyst either in convention photocatalysis or in emerging flow photocatalytic H₂O₂ production. The N-vacancies multifunctionally enhance light harvesting, elevate conduction band, adsorb and activate O₂ molecules. As a result, the N-defective CNNRs delivered 5.2 and 2.1 times higher H₂O₂ yield in its powder form than common CN nanosheets and defect-free CNNRs, reaching 18.8 mmol g^-1 h^-1 with AQY of 13.4 % at 400 nm in ethanol-containing solution. Moreover, the CNNRs on glass, as a photocatalyst panel, exhibits remarkable fixed-bed and continuous flow photocatalytic H₂O₂ production performances, with yield up to 23.6 and 14.2 mmol m^-2 h^-1, respectively. Mechanism investigation discloses the sequential two-step 1e oxygen reduction pathway that accounts for H₂O₂ photogeneration, with further thermal-dynamical confirmation by DFT calculation. This work introduces a new paradigm by combining photocatalyst design with advanced flow reactors to achieve continuous photosynthesis of H₂O₂, which may inspire many other photo-to-chemical conversions as well.