Hollow Covalent Organic Framework Cages with Zn Ion-Implantation Promoting Photocatalytic H2 Evolution

Covalent organic frameworks (COFs) are emerging as a class of photocatalyst for solar energy utilization. The separation of photogenerated excitons in COFs is crucial for their photocatalytic performance. Herein, we report a strategy to tune the electronic structure of COFs by implanting Zn ions within the framework to facilitate the separation and utilization of the photoinduced charges. Zn ions are incorporated within the shell of hollow COF cages (Zn@H-TpPa) by a sacrificial template method with a formation of hollow cages. The implantation of Zn ions within the framework results in a redistribution of electron density and an increment of the polarity of the COF, as evidenced by experimental and computational analyses, and thus contributes to the separation and transport of charge carries. The Zn@H-TpPa shows enhanced photocatalytic H-2 production efficiency as compared to TpPa. The results demonstrate a new way to optimize the electronic structure of COFs for photocatalysis.