Covalent Organic Framework Constructed By Clicking Azido Porphyrin With Perpropargyloxy-Cucurbit[6]Uril For Electrocatalytic Hydrogen Generation From Water Splitting

In the present study, we describe the synthesis and characterization of a new covalent organic framework (COF-TPP-CB[6]) which was assembled together by clicking perpropargyloxy cucurbit[6]uril (CB[6]) to the azido-functionalized tetraphenylporphyrin (TPP-4N(3)) through a copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC). Perpropargyloxy CB[6] was synthesized through the direct oxidation of CB[6] to afford perhydroxy CB[6] followed by subsequent O-propargylation using NaH. We also demonstrated that the resulting framework (COF-TPP-CB[6]) can be employed as an efficient and stable electrocatalyst for hydrogen evolution reaction (HER) in alkaline medium upon loading it with a nickel cocatalyst. The effect of TiO2 and different loadings of Ni on the HER performance of TPP-CB[6] was also studied. Herein, 12%Ni@ TPP-CB[6] as the optimum catalyst showed an impressive H2 production rate of 18.7 mmol h(-1 )g(-1) with a low onset potential of -250 mV.