Towards Artificial Thylakoids: Charge Transfer in Polydopamine Nanosheets for Photocatalytic Hydrogen Production

Artificial leaves emulate biological leaves by converting photonic energy into chemical energy, yet replicating photosynthetic functionalities at the molecular level remains a challenge. Key limitations of current artificial leaves include recombination in photosensitizers (1) and photooxidation of the photosensitizers (2), inefficient electron and proton transfer to reaction centers (3), and limited scalability of the illuminated surface area (4). Herein, we address these challenges by mimicking the thylakoid membrane, nature's photosynthetic machinery, using an electropolymerized ultrathin polydopamine (PDA) nanosheet embedded with CdSe@CdS nanorods (NRs) as photosensitizers and cobaloximes as hydrogen evolution catalysts. The PDA nanosheet provides essential functions of the thylakoid membrane: it suppresses recombination through rapid electron acceptance, facilitates efficient electron transfer and mitigates photooxidation of photosensitizers within an ultrathin layer, as demonstrated by transient absorption spectroscopy, scanning electrochemical microscopy, and photoelectrochemical analysis. These findings lay the groundwork for designing artificial thylakoid membranes, advancing the development of next-generation materials for efficient energy conversion and addressing some of the fundamental limitations of current artificial leaf systems.