Photoactive PDI–Cobalt Complex Immobilized on Reduced Graphene Oxide for Photoelectrochemical Water Splitting

We report the synthesis of a perylene derivative (perylene tetracarboxylic di(propyl imidazole), abbreviated as PDI) that is coordinated with Co(II) ions to form a coordination polymer [PDI-Co(Cl)2(H2O)2]n (abbreviated as PDI-Co). The PDI-Co complex combines the photoactivity of the perylene dye with the electrocatalytic activity of the "Co(II)" center for photoelectrochemical hydrogen evolution reaction (HER). To improve charge transfer interactions, the PDI-Co complex is immobilized on reduced graphene oxide (rGO) via noncovalent interactions to form the rGO-PDI-Co complex. The composite shows good performance in multiple cycle testing and the turnover number (TON vs Co(II)) of this hybrid material for hydrogen evolution reaction (754 after 5 h) is considerably higher than previously reported dye-sensitized cobalt-based catalysts.