Regeneration of NAD(P)H and its Analogues by Photocatalysis with Ionized Carbon Nitride

The regeneration of NAD(P)H and its analogues is crucial for biocatalytic processes. However, despite the efficiency of enzymatic catalysis in regenerating NAD(P)H, the sustainability of enzymes is often compromised, particularly under extreme catalytic conditions. Moreover, artificial cofactors may present advantages in certain reactions due to their stability and versatility, yet the substrate specificity of enzymes poses significant challenges to their regeneration through the enzymatic method. Therefore, it is imperative to develop a highly stable regeneration method that can be adapted to both natural and artificial cofactors. In this work, employing potassium-ion-doped carbon nitride (ionCN-0.2) as a catalyst not only achieves high-efficiency photocatalytic regeneration of NAD(P)H, comparable to that of glucose dehydrogenase (GDH), but also a remarkable ability to regenerate nicotinamide analogues. This enhanced performance stems from the tunable negative ζ-potential, which effectively adsorbs the positively charged [Cp*Rh(bpy)H2O]2+ mediator, resulting in enhanced regeneration kinetics of the nicotinamide moiety. The catalyst demonstrates superior performance compared to the reported systems; the optimal regeneration rate reaches 0.55 mmol L–1 gcat–1 min–1 and approaches enzymatic regeneration efficiency. Expanding the reaction conditions to a wider temperature and pH range also confirms the effectiveness and sufficient stability of this photocatalytic system, offering a promising strategy for stable cofactor regeneration in biocatalytic processes.