Boskovic, DanijelTerrett, RichardLonghurst, MatthewBasheer, SabeelAriafard, AlirezaWagner, PawelPace, Ronald J.Stranger, RobSwiegers, Gerhard F.2025-05-232025-05-231477-9226PubMed:39495212ORCID:/0000-0003-2383-6380/work/184103493http://www.scopus.com/inward/record.url?scp=85208816179&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733752064The activity and stability of a heterogeneous water oxidation catalyst inspired by the Photosystem II - Oxygen Evolving Center (PSII-OEC) is reported. Ca-doped birnessite MnOx supported on a liquid crystalline reduced graphene oxide (LCrGO) substrate exhibited unprecedented performance for an abiological catalyst at pH 7, including an exceedingly low onset overpotential of 0.52 V (vs. 0.48 V reported for the PSII-OEC, 0.75 V for Pt, and 0.72 V for birnesite MnOx) and remarkably high activity per unit area at 0.56 V overpotential (∼10% that of a hypothetical, closely-packed monolayer of OEC sites at their optimum density of 1014 sites per cm2).This work was financially supported by the Australian Renewable Energy Agency (ARENA), contract number 2018/RND004. This activity received funding from ARENA as part of ARENA's Research and Development Program-Renewable Hydrogen for Export. SMB thanks the Australian Government for an Endeavour Fellowship. The authors thank: Rouhollah Jalili for the LCGO, Attila Mozer for use of a gas chromatograph, and George Tsekouras for advice. The authors acknowledge support from: the Australian National Fabrication Facility (ANFF) Materials Node, the Australian Research Council (Project Numbers CE140100012, and LE160100063).6enPublisher Copyright: © 2024 The Royal Society of Chemistry.2024-10-2910.1039/d4dt02336f85208816179