In-plane electric field induced by cyano groups and graphitic carbon structure for enhancing photocatalytic hydrogen production of carbon nitride

Abstract

Inducing an intrinsic driving force into a two-dimensional semiconductor plane to boost the separation and transfer of photoexcited electrons and holes near the photoexcited sites is an effective way of suppressing the recombination of photogenerated carriers. In this work, a photocatalyst (CN-g-C3N4-C) with in-plane continuous π-conjugated bonds was developed by introducing cyano groups (abbreviated as CN) and graphitic carbon (abbreviated as C) in the in-plane structure of carbon nitride (g-C3N4). Different from traditional interface modulation approaches based on the van der Waals forces or hydrogen bonds, chemical bonds are formed between the cyano groups and graphitic carbon component in the CN-g-C3N4-C atomic junction, which facilitate the efficient migration of photogenerated carriers. The ultra-thin porous lamellar structure of CN-g-C3N4-C not only shortens the carrier transfer distance, but also effectively increases the specific surface area. In the CN-g-C3N4-C plane, the strong in-plane electric field can drive the orderly transfer of photoexcited electrons and holes to the graphitic carbon end and the cyano group end, respectively, resulting in enhanced separation and transfer of the electrons and holes near the photoexcited sites. Due to its high charge carrier separation efficiency, CN-g-C3N4-C possesses excellent photocatalytic activity, and its hydrogen production rate is 14.8 times higher than that of pristine g-C3N4. This work provides an atomic-level strategy for designing efficient and economical photocatalysts.