Constructing tightly integrated conductive metal-organic framework/covalent triazine framework heterostructure by coordination bonds for photocatalytic hydrogen evolution

[Display omitted] •Coordinately linked Ni-CAT-1/CTF-1 heterostructure was successfully constructed.•Coordination connection greatly reduces the barrier to charge transfer in the interface.•Conductive Ni-CAT-1 further facilitates the separation of photogenerated carriers from CTF-1.•Ni-CAT-1/CTF-1 shows significantly enhanced photocatalytic hydrogen evolution activity. The construction of tightly integrated heterostructures with metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) has been confirmed to be an effective way for improved hydrogen evolution. However, the reported tightly integrated MOF/COF hybrids were usually limited to the covalent connection of COFs with aldehyde groups and NH2-MOF via Schiff base reaction, restricting the development of MOF/COF hybrids. Herein, a covalent triazine framework (CTF-1), a subtype of crystalline COFs, was integrated with a conductive two-dimensional (2D) MOF (Ni-CAT-1) by a novel coordinating connection mode for significantly enhanced visible-light-driven hydrogen evolution. The terminal amidine groups in the CTF-1 layers offer dual N sites for the coordination of metal ions, which provides the potential of coordinating connection between CTF-1 and Ni-CAT-1. The conductive 2D Ni-CAT-1 in Ni-CAT-1/CTF-1 hybrids effectively facilitates the separation of photogenerated carriers of CTF-1 component, and the resultant hybrid materials show significantly enhanced photocatalytic hydrogen evolution activity. In particular, the Ni-CAT-1/CTF-1 (1:19) sample exhibits the maximum hydrogen evolution rate of 8.03 mmol g−1h−1, which is about four times higher than that of the parent CTF-1 (1.96 mmol g−1h−1). The enhanced photocatalytic activity of Ni-CAT-1/CTF-1 is mainly attributed to the incorporation of conductive MOF which leads to the formation of a Z-Scheme heterostructure, promoting the electron transfer in hybrid materials. The coordinating combination mode of Ni-CAT-1 and CTF-1 in this work provides a novel strategy for constructing tightly integrated MOF/COF hybrid materials.