Granular Polymeric Carbon Nitride with Carbon Vacancies for Enhanced Photocatalytic Hydrogen Evolution

Considering the high charge recombination rate, low optical adsorption intensity and limited active sites greatly constrict the solar-to-chemical conversion efficiency of polymer carbon nitride. Herein, a facile approach is reported to produce defected polymeric carbon nitride (PCN) with abundant granular bulks with fractured boundaries by thermal reduction treatment in CO atmosphere. The photocatalytic hydrogen evolution over defected PCN exhibits a rate of 3281.2 mu mol g(-1) h(-1), 3.5 times higher than the pristine, which is most possibly ascribed to the following factors. The unique defected and porous structure not only provides higher specific surface area, more exposed active edges, abundant charge separation sites, and active centers for hydrogen generation but also is beneficial to rapid mass and charge transfer, interior diffusing of incident light, and shortening carrier transport length, thus enhancing the optical adsorption and accelerating the photocatalytic reaction kinetics. Furthermore, the electron delocalization at carbon vacancies sites on one hand facilitates the separation rate of electron-hole pairs and prolonged the carrier lifetime; on the other hand, the electronic polarization caused by C atoms loss helps increasing the affinity between catalyst and substrate reactant. Moreover, the higher electron donor density and lower conduction band minimum (CBM) potential further enhance the reduction capacity for H-2 evolution.

Automated summary

A facile approach was reported to produce defected polymeric carbon nitride with abundant granular bulks by thermal reduction treatment in CO atmosphere, leading to enhanced photocatalytic hydrogen evolution efficiency. The unique defected and porous structure not only provides more active sites and charge separation sites, but also facilitates rapid mass and charge transfer, accelerating photocatalytic reaction kinetics.