Organic-inorganic photosynthetic interfaces built on intertwined WO 3 nanosheets for enhanced HBr/H 2 O photoanodic oxidations J. Liu a , I. Crea a,b , T. Gobbato a,b , F. Rigodanza a,b , G. A. Rizzi a , E. Benazzi a * and M. Bonchio* a,b a Department of Chemical Sciences, University of Padova, 35131 Padova, Italy, b Istituto per la Tecnologia delle Membrane INSTM-section of Padova, ITM-CNR, University of Padova, Department of Chemical Sciences, University of Padova, 35131 Padova, Italy *E-mail: elisabetta.benazzi@unipd.it, marcella.bonchio@unipd.it Using a sacrificial ZnO template, we report the fabrication of FTO-based photoanodes displaying a porous network of interconnected 3D-tungsten oxide nanosheets (WO 3 3D-NS), with diameter/thickness distribution respectively in the range 0.20 – 0.94 µm and 10 – 40 nm, leading to record aspect ratios (~ 100) with respect to literature benchmarks (~ 10) 1 and dominant {001} facets. WO 3 3D-NS provide an ideal platform for shaping hybrid photosynthetic interfaces by deposition of supramolecular perylenebisimide polymers (PBI n ). The combined WO 3 3D-NS|PBI n are probed for photoelectrochemical HBr splitting using low energy photons (λ> 450 nm), with up to a 200 % increase of the state-of-the-art performance based on WO 3 -analogs (J > 0.3 mA cm -2 at 0.85 V vs RHE). Structure vs reactivity comparison with WO 3 microplates (WO 3 MP) and inverse opal (WO 3 IO) points to a favorable enhanced active surface area of WO 3 3D-NS exposing dominant {001} facets, which promote PBI sensitization and charge transfer at the photoanode|electrolyte interface. Building on this technology, a > 50% improvement of photoanodic water splitting is achieved using the WO 3 3D-NS photoanode as platform for the core-shell self-assembly of the PBI based quantasome architecture (QS), templated around the tetra-ruthenated polyoxometalate as oxygen evolving catalyst ({[PBI] 5 Ru 4 POM} n ). Rendering the bio-inspired QS 2-4 on the WO 3 3D- NS surface yields an incident-photon-to-current-conversion efficiency (IPCE) of 0.67%, using green photons for oxygenic photosynthesis (500 nm at 0.91 V vs RHE) which stems from a multi-heterojunction molecular array for light harvesting and charge transport, representing a significative advancement in the field. References 1. Novak, T. G., Kim, J., DeSario, P. A.,Jeon, S., Synthesis and applications of WO(3) nanosheets: the importance of phase, stoichiometry, and aspect ratio, 2021, Nanoscale Adv, 3, 5166, https://doi.org/10.1039/D1NA00384D 2. Bonchio, M., Syrgiannis, Z., Burian, M. , et al., Hierarchical organization of perylene bisimides and polyoxometalates for photo-assisted water oxidation, 2019, Nat Chem, 11, 146, https://doi.org/10.1038/s41557-018-0172-y 3. Gobbato, T., Rigodanza, F., Benazzi, E. , et al., Enhancing Oxygenic Photosynthesis by Cross-Linked Perylenebisimide "Quantasomes", 2022, J Am Chem Soc, 144, 14021, https://doi.org/10.1021/jacs.2c05857 4. Ranscht, A., Rigodanza, F., Gobbato, T. , et al., Combined Covalent and Supramolecular Polymerization to Reinforce Perylenebisimide Photosynthetic "Quantasomes", 2024, Chemistry, 30, e202303784, https://doi.org/10.1002/ chem.202303784
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