A high-cyano groups-content amorphous-crystalline carbon nitride isotype heterojunction photocatalyst for high-quantum-yield H2 production and enhanced CO2 reduction

Polymeric carbon nitride suffers terrible recombination of photo-generated carriers and thus usually results in limited photocatalytic activity. Improving crystallinity and creating novel structure can effectively alleviate the aforementioned problem. Herein, a high-cyano groups-content and amorphous-crystalline carbon nitride isotype heterojunction (BCN-NaK) was obtain via a post treatment strategy in eutectic salt. The cyano groups acted as electron acceptors, and the intimate isotype heterojunction constructed by amorphous carbon nitride and crystalline poly-heptazine-imide built interfacial electric field. Both synergistically enabled BCN-NaK more efficient charge transfer than other amorphous and crystalline carbon nitrides. Comprehensive and systematic analysis demonstrated that the promoted charge transfer made the predominant contribution to the ultrahigh photocatalytic H2-production activity of BCN-NaK with an excellent apparent quantum yield of 68.9 % at 405 nm. In addition, BCN-NaK exhibited a good photocatalytic CO2-to-CO conversion rate of 22.8 μmol h−1 gcat−1 without adding sacrificial agent or loading metal under visible light.