Soft-template synthesis of sp2-carbon linked polymeric carbon nitride porous nanotubes with enhanced photocatalytic hydrogen evolution

Abstract

Morphological and structural modifications are effective ways to improve the photocatalytic performance of polymeric carbon nitride (CN), a promising photocatalyst for industrial application, but research on simultaneous morphological control and covalent bond insertion in CN and relevant structure-function relationships are still rare. Herein, sp2-carbon linked CN (C-CN) porous nanotubes were simply synthesized by first using polyethyleneimine as the template and modifying agent, and exhibit an enlarged specific surface area, enhanced visible light absorption and charge separation, originating from the sp2-C introduced impurity level in the bandgap, and thus improved photocatalytic H2 evolution activity under visible light irradiation, compared with the bulk CN. Interestingly, the photoactivity of C-CN at wavelengths of 400 and 420 nm is lower than CN because of the sp2-C insertion induced reduction of amino groups which are active sites for H2 evolution. That is, the photoactivity enhancement of C-CN is λ-dependent. This work elucidates the sp2-C linked structure-performance relationship of C-CN, and may direct future research on atom-linked mesoporous CN-based photocatalysts.