Construction of Double S-Scheme ZIF-67@GDY/CuI Heterojunction by Graphdiyne (g-CnH2n-2) Nanosheets-Coated ZIF-67 on Synergized Charge Transfer for Enhanced Photocatalytic Hydrogen Evolution

Graphdiyne (GDY) is a carbon allotrope material composed of sp and sp(2) hybrid carbon atoms, which has been proven to be a good carrier for anchoring metal catalysts due to its abundant alkyne bonds. Herein, a double S-scheme ZIF-67@GDY/CuI heterojunction with graphdiyne (g-CnH2n-2) nanosheets-coated ZIF-67 is prepared by a simple mixing method. The ZIF-67 dodecahedron coated with GDY nanosheets constructed S-scheme heterojunction by matching valence and conduction bands. The double S-scheme heterojunction can maintain the strong redox ability of photogenerated electron-hole pairs well and promote more efficient charge transport. The excellent charge transport path is also attributed to the unique double S-scheme heterojunction, which is confirmed by in situ X-ray photoelectron spectroscopy. Moreover, the electron migration from ZIF-67 to GDY generates an internal electric field (IEF), which improves the light energy utilization and charges separation efficiency under the condition of the IEF, band edge bending, and coulomb interaction. The optimal hydrogen production rate of ZIF-67@GDY/CuI-20 is 7.27 mmol g(-1) h(-1) under visible light irradiation, which is significantly increased by 4.75 times compared with the unmodified ZIF-67. Herein, a new possibility for the construction of double S-scheme heterojunction based on graphdiyne to improve photocatalytic performance is provided.

Automated summary

A double S-scheme ZIF-67@GDY/CuI heterojunction is prepared, which shows improved photocatalytic performance. The optimized ZIF-67@GDY/CuI-20 exhibits a hydrogen production rate 4.75 times higher than the unmodified ZIF-67 under visible light irradiation.