Double duty: Covalently grafting a nickel thiolate molecular catalyst onto a covalent organic framework significantly enhances the photocatalytic hydrogen evolution reaction. p-Aminothiophenol serves not only as a modulating agent to enhance the crystallinity, but also as a ligand to anchor NiII ions.
Covalent organic frameworks (COFs) have recently emerged as prospective photoactive materials with noble Pt as a cocatalyst for photocatalytic hydrogen evolution. In this work, a series of SH-group-functionalized covalent organic frameworks, TpPa-1-SH-X, is prepared by reaction of p-phenylenediamine (Pa) and 1,3,5-triformylphloroglucinol (Tp) with p-NH2C6H4SH as a modulating agent. The reaction of TpPa-1-SH-X with NiII acetylacetonate Ni(acac)2 gave nickel thiolate-immobilized TpPa-1 (TpPa-1-SNi-X). The highest hydrogen evolution rate was 10.87 mmol h−1 g−1, which was an enhancement of 16.47, 3.83, and 1.84 times than that of the parent TpPa-1, covalent-bond-free [(p-NH2C6H4S)2Ni]
/TpPa-1-SH-10, and 3 wt % Pt-deposited TpPa-1, respectively. This enhanced photocatalytic hydrogen evolution is ascribed to enhanced crystallinity, the use of NiII thiolate as a cocatalyst and covalent bonding between the cocatalyst and TpPa-1.Zum Volltext