Dual-Defect Abundant Graphitic Carbon Nitride for Efficient Photocatalytic Nicotinamide Cofactor Regeneration

Photocatalyticregeneration of valuable cofactors by using sunlighthas emerged as a promising strategy for biosynthesis and pharmaceuticalmanufacturing. Graphitic carbon nitride (g-C3N4) is very suitable for photocatalytic nicotinamide cofactor regenerationsince it is metal-free, visible-light responsive and has strong bindingwith nicotinamide cofactor. However, its great potential is hinderedby some intrinsic drawbacks such as low visible absorption, fast electron/holerecombination, and limited active sites. Here, we demonstrate dual-defectg-C3N4 (DDCN) with controllable defects of nitrogenvacancies and cyano groups for efficient photocatalytic cofactor regenerationvia a KOH-assisted thermal polymerization by using urea as a precursor.Although DDCN is widely used for other photocatalytic applicationssuch as organic degradation and hydrogen peroxide production, thiswork is original in its application to photocatalytic cofactor regeneration.Material characterizations confirm the successful introduction ofnitrogen vacancies and cyano groups. Measurements of nicotinamide-cofactorgeneration show that the DDCN samples assisted with 0.1 g and 0.01g KOH are 3.0 and 2.5 times that of pristine g-C3N4 in terms of nicotinamide cofactor yield, respectively. Thehigh yields are attributed to the synergetic effect of both enhancedlight absorption and improved charge separation, achieved throughthe introduction of energy levels and trap states via dual defects.This work provides a green, energy-saving, and promising strategyfor nicotinamide cofactor regeneration and would promote its applicationin biosynthesis and drug manufacturing. Nonmetalgraphitic carbon nitride with abundant dual defectsenables photocatalytic regeneration of nicotinamide cofactors withfacile synthesis and high efficiency.