Carbohydrate-regulated synthesis of ultrathin porous nitrogen-vacancy polymeric carbon nitride for highly efficient Visible-light hydrogen evolution

• Construction of ultrathin porous N-vacancy PCN from carbohydrate. • The N-vacancy and pore volume of the photocatalyst can be adjusted. • The specific surface area of PCN-G was 17.7 times that of PCN. • PCN-G exhibited an excellent H 2 production rate under visible light. Morphologies and electronic structures of the photocatalysts play a critical role in governing their photocatalytic actives via providing large specific surface area (more active sites) and suitable band structure. To achieve high visible-light photocatalytic activity, herein, an ultrathin porous nitrogen-vacancy polymeric carbon nitride (PCN) was synthesized by high-temperature thermal polymerization using melamine with a biomass derived carbohydrate aqueous solution, offering a flexible nature to finely tune the vacant and porous structures through properly changing the carbohydrate. The ultrathin porous structure could significantly enhance the specific surface area of PCN and improve the mobility of charges. Moreover, the induced vacancies structures could largely expand the light absorption range and reduce the recombination rate of photogenerated carriers. These led to an excellent photocatalytic activity for H 2 production, with the optimal hydrogen evolution rate 17.2 times (5.5 mmol h -1 g -1 , 1 wt.% Pt as a co-catalyst) higher than that of the unmodified PCN (0.32 mmol h -1 g -1 ). These results provide a simple, effective, and cost-effective strategy for the synthesis of novel photocatalysts using biomass-based raw materials to obtain a highly active photocatalyst with simultaneous adjusting the vacancies and porous structures.