Atomic carbon chain-linked polymeric carbon nitride: Roles of the carbon chain in enhancing the photocatalytic hydrogen evolution performance

Atomic carbon chain insertion into polymeric carbon nitride introduces an impurity level in the bandgap that induces enhancement in visible light absorption, charge separation, and photocatalytic H2 evolution under visible light irradiation, however, with reduction of amino groups unfavorable for the photoactivity improvement. [Display omitted] •Atomic carbon chain linked polymeric carbon nitride (ACC-CN) was prepared.•ACC insertion introduces an impurity level in the bandgap of ACC-CN.•ACC-CN exhibits enhanced visible light absorption and charge separation.•ACC-CN exhibits enhanced visible-light photocatalytic H2 evolution.•ACC-CN possesses reduced active sites for H2 evolution. The atomic carbon chain (ACC) insertion is an effective strategy to enhance the photocatalytic H2 evolution of polymeric carbon nitride (CN), a photocatalyst with great potential for practical application, but the roles of ACCs need be deeper researched to distinctly clarify the structure-activity relationship. Herein, an ACC linked CN (ACC-CN) was simply synthesized by using benzoquinone as the linking agent, and exhibits the H2 evolution rates of ∼5.9 times and ∼50 % that of the bulk CN at wavelengths (λ) of 480 and 420 nm, respectively, i.e., a λ-dependent photoactivity enhancement. The photoactivity improvement of ACC-CN benefits from its considerably extended visible light absorption and enhanced charge separation, caused by the ACC introduced impurity level in the bandgap of ACC-CN. This work provides deep insight into the roles of ACCs in ACC-CN, favorable for future development of carbon chain modified CN photocatalysts.