Organic‐Inorganic Photosynthetic Interfaces Built on Intertwined WO3 Nanosheets for Enhanced HBr/H2O Photoanodic Oxidations

Using a sacrificial ZnO template, this study report the fabrication of fluorine-doped tin oxide (FTO)-based photoanodes displaying a porous network of interconnected 3D-tungsten oxide nanosheets (WO3 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) and dominant {001} facets. WO3 3D-NS provide an ideal platform for shaping hybrid photosynthetic interfaces by deposition of supramolecular perylenebisimide polymers (PBIn). The combined WO3 3D-NS|PBIn are probed for photoelectrochemical HBr splitting using low energy photons (λ > 450 nm), with up to a 83% increase of the state-of-the-art performance based on WO3-analogs (J > 0.3 mA cm−2 at 0.85 V vs. reversible hydrogen electrode (RHE)). Structure versus reactivity comparison with WO3 microplates (WO3 MP) and inverse opal (WO3 IO) points to a favorable enhanced active surface area of WO3 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 WO3 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]5Ru4POM}n). Rendering the bio-inspired QS on the WO3 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 multiheterojunction molecular array for light harvesting and charge transport, representing a significative advancement in the field.