Supramolecular Catalyst with [FeCl4] Unit Boosting Photoelectrochemical Seawater Splitting via Water Nucleophilic Attack Pathway

Abstract

Abstract Propelled by the structure of water oxidation co-catalysts in natural photosynthesis, molecular co-catalysts have been believed for a long time to possess the developable potential in artificial photosynthesis. However, the interfacial complexity between a light absorber and the molecular co-catalyst limits its structure stability against pH value and charge transfer efficiency. To overcome the challenge, a supramolecular scaffold with the catalytic unit instead of the molecular structure is, for the first time, reported. It is found that the [FeCl4] catalytic sites in the supramolecular matrix (polythiophene, polyaniline, or polypyrrole) undergo a water-nucleophilic attack defining the rate-limiting step of the water oxidation reaction, while the supramolecular matrix can be in situ grown on the surface of photoelectrode to enable a strongly coupled interface. A well-defined BiVO4 photoanode surface hybridized with [FeCl4] catalytic sites in polythiophene matrix reaches 4.72 mA cm− 2 at 1.23 V vs reversible hydrogen electrode under AM 1.5 G illumination, which also exhibits great stability for photoelectrochemical seawater splitting due to the restraint on chlorine evolution reaction by [FeCl4] unit, the anti-corrosion ability of polythiophene as well as the strongly coupled interface. This work provides a novel solution to the challenge of the interface charge transfer of molecular co-catalyst hybridized photoelectrode.