Nanoporous Graphitic Carbon Nitride as Catalysts for Cofactor Regeneration

An efficient nicotinamide adenine dinucleotide (NADH) regeneration system is of great significance for the application of oxidoreductase-catalyzed reactions. Photochemical regeneration has been a research hotspot in recent years. Graphite carbon nitride (g-C3N4) has important application prospects. However, bulk g-C3N4 (BCN) has some disadvantages that lead to a low catalytic efficiency. Herein, nanoporous g-C3N4 (PCN) was prepared using silica nanoparticles as templates, and the effects of the mass ratio of cyanamide to silica and the particle size of the templates on the structure, optical, and catalytic properties of PCN were investigated. Then, cyanamide was separately co-polymerized with two types of thiophene compounds and imidazole-, benzene-, and quinolone-based compounds, and the effects of the structure and number of aromatic rings introduced into PCN on the properties of catalysts were studied. The results show that PCN had much better catalytic performance than BCN, the initial reaction rate of NADH regeneration could be upgraded from 18.01 to 37.14 mmol/(g·min) after PCN was modified with thiophene compound, and the yield of NADH after 20 min increased from 56.8 to 82.7%. When other aromatic compounds were added in the PCN preparation process, a catalytic performance similar to that of thiophene-modified PCN was acquired.