Metal-Free Light-Driven 1,4-NADH Regeneration System from Nitrogen and Sulfur Codoped Carbon Dots

Light-driven regeneration of nicotinamide cofactors, primarily NADH, is of great significance for enzyme-photocoupled artificial photosynthesis, which strongly relies on the utilization of noble metal-based cocatalysts to ensure high selectivity of 1,4-NADH. Herein, we report a metal-free photocatalytic NADH regeneration system enabled by nitrogen and sulfur codoped carbon dots (N,S-CDs). The temporary occupation of the S element during catalyst synthesis increased the proportion of pyrrolic N by 2.05 times. The high proportion (88.44%) of pyrrolic N in N,S-CDs affords appropriate adsorption energy toward #4 carbon of the NAD+ pyridine ring. As a result, N,S-CDs exhibited a selectivity of 82.00 ± 5.64% toward 1,4-NADH, the highest value in the existing metal-free systems, which also showed a size-dependent 1,4-NADH regeneration yield with an optimal value of 42.92 ± 2.24%.