Influence of O–O formation pathways and charge transfer mediator on lipid bilayer membrane-like photoanodes for water oxidation

Through the lipid bilayer membrane-like photoanodes and Ru-bda catalysts with different O-O bond formation pathways, the rate determine step of the dye-sensitized photoelectrochemical was determined to be the electron transfer rather than the water oxidation reaction. The electron transfer can be promoted by ICZ as the charge transfer mediator. [Display omitted] Inspired by the function of crucial components in photosystem II (PSII), electrochemical and dye-sensitized photoelectrochemical (DSPEC) water oxidation devices were constructed by the self-assembly of well-designed amphipathic Ru(bda)-based catalysts (bda = 2,2ʹ-bipyrdine-6,6ʹ-dicarbonoxyl acid) and aliphatic chain decorated electrode surfaces, forming lipid bilayer membrane (LBM)-like structures. The Ru(bda) catalysts on electrode-supported LBM films demonstrated remarkable water oxidation performance with different O–O formation mechanisms. However, compared to the slow charge transfer process, the O–O formation pathways did not determine the PEC water oxidation efficiency of the dye-sensitized photoanodes, and the different reaction rates for similar catalysts with different catalytic paths did not determine the PEC performance of the DSPECs. Instead, charge transfer plays a decisive role in the PEC water oxidation rate. When an indolo[3,2-b] carbazole derivative was introduced between the Ru(bda) catalysts and aliphatic chain-modified photosensitizer in LBM films, serving as a charge transfer mediator for the tyrosine-histidine pair in PSII, the PEC water oxidation performance of the corresponding photoanodes was dramatically enhanced.