Cryo-induced closely bonded heterostructure for effective CO2 conversion: The case of ultrathin BP nanosheets/g-C3N4

• The cryo-induced closely bonded 2D BP/2D g-C 3 N 4 heterostructure exhibits higher activity than pure g-C 3 N 4 . • The 2D BP/2D g-C 3 N 4 heterostructure is for the first time applied to the CO 2 photoreduction. • The introduction of 2D BP can enhance the absorbance of light and accelerate the transfer of the photogenerated carriers. Black phosphorus (BP), an interesting and multi-functional non-metal material, has attracted widespread attention. In this work, 2D BP/2D g-C 3 N 4 heterostructure had been fabricated at extremely low temperature, which was used to reduce CO 2 for the first time. With introduction of 2D BP, the separation of photogenerated holes and electrons was extremely boosted, and composites showed excellent photocatalytic performance (CO 2 to CO). Meanwhile, the targeted composite could keep high selectivity for CO generation and CO generation rate can be up to 187.7 μmol g −1 h −1 . The formation process of the unique heterostructure and the key factor affecting the photocatalytic performance were also discussed. This work provides a new approach for designing metal free photocatalyst, which is used for CO 2 reduction. Cryo-induced closely bonded 2D BP/2D g-C 3 N 4 heterostructure had been prepared. For the first time, it was used to capture CO 2 , which can effectively convert CO 2 to CO with long-term stability.