Bifunctional Polydopamine Layer Enables Two-Dimensional Conjugated Polymer Thin Films on Solid Substrates for High-Efficiency Photo(electro)catalysis

Developing stable, effective photo(electro)catalytic devices is important for solar fuels production. However, the challenge in robust and controllable growth of 2D conjugated polymers, especially sp2 carbon-conjugated covalent organic frameworks (sp2 C-COFs), on solid substrates imposes limitations on their advanced photo(electro)catalysis. Here, we pioneer a polydopamine (PDA) mediated strategy for synthesizing thin films of sp2 C-COFs. The PDA layer not only provides binding sites for self-catalyzed Schiff-base reaction initiation and strong adhesion but also facilitates efficient charge separation via a phenol-quinone redox shuttle. Time/spatial-resolved spectroscopic techniques reveal that the favored interfacial charge separation is realized by fast photogenerated hole transfer from sp2 C-COFs to PDA. Benefiting from the bifunctional role of PDA, the PSTMP-TFPT film shows outstanding photocatalytic H2 production activity of ∼120 mmol m–2 h–1 and a remarkable increase in photocurrent density at low loading of the photocatalyst, highlighting its potential for highly efficient and material-economic photo(electro)catalytic devices.