Mechanochemical Synthesis of Nitrogen-Deficient Mesopore-Rich Polymeric Carbon Nitride with Highly Enhanced Photocatalytic Performance

Creation of defects and mesopores in polymeric carbon nitride (CN), a promising photocatalyst for practical applications, is highly effective in enhancing the photocatalytic performance; however, environmentally friendly physical methods (e.g., mechanical ball-milling) and effective means for the simultaneous formation of defects and mesopores in CN to synergistically enhance the photoactivity are still scarce. Herein, a mechanochemical method was successfully used to synthesize mesopore-rich CN with nitrogen vacancies (mCNv) by mechanical ball-milling of the intermediate (melem) with succedent calcination. The simultaneous formation of nitrogen vacancies and mesopores in mCNv arises from the ball-milling-induced structure distortion and morphological variation of the intermediate with massive rupture of intermolecular hydrogen bonds. The as-prepared mCNv exhibits enlarged specific surface area, considerably thinned nanosheets, extended visible light absorption, enhanced photoexcited charge separation and transfer, and thus similar to 6.3-fold improved photocatalytic H-2 evolution activity under visible light irradiation, compared with the bulk CN. This work provides a novel, universal, and industrializable technique for simultaneous creation of defects and mesopores in CN.