Guided re-design of 3D porous electrodes for biophotoelectrochemical systems: a simulation-informed approach Linying Shang 1 , Sing Teng Chua 1,2 , Joshua Lawrence 1 , Laura Wey 3 , Silvia Vignolini 1,4 , Christopher Howe 1 , Jenny Zhang 1 1 University of Cambridge, UK, 2 University of Copenhagen, Denmark, 3 University of Turku, Finland, 4 Max Planck Institute of Colloids and Interfaces, Germany Living biophotoelectrochemical systems integrate photosynthetic microorganisms—sustainable and scalable biocatalysts—with abiotic materials to drive solar-powered electricity generation or fuel production. 1 A critical component of these systems is the three-dimensional (3D) electrode, which facilitates energy and electron transfer across the biotic–abiotic interface. These electrodes must meet multiple design criteria: biocompatibility to support microorganisms, optical accessibility for effective light harvesting, electrical conductivity for efficient electron transfer and stability for long-term operation. State-of-the-art electrodes in this field include micropillar (MP) and inverse opal (IO) structures, both composed of indium tin oxide (ITO) nanoparticles. MP-ITO electrodes deliver benchmark photocurrent outputs but require specialised 3D printing for fabrication. 2 In contrast, IO-ITO electrodes can be produced using standard benchtop techniques after optimisation. 3-5 Despite their high surface area, IO-ITO structures often underperform due to inefficient light management. 2 To address this, we systematically varied pore size (10–100 μm) and thickness to optimise light distribution, guided by Monte Carlo-based light simulations, which also reduced the fabrication optimisation workload. We evaluated the resulting structures in terms of electroactive surface area, biocatalyst- loading and overall biophotoelectrochemical performance. Our results show that increasing the thickness of 10 μm pore-sized IO-ITO electrodes alone did not lead to proportionally higher biocatalyst-loading or photocurrent output. In contrast, IO-ITO electrodes with larger pore sizes achieved a better balance between light penetration and biocatalyst accessibility, resulting in the highest photocurrent output under non-light-limiting conditions. However, under light-limiting conditions, optimised light management became more crucial. IO-ITO electrodes with improved light accessibility outperformed others when normalised by biocatalyst-loading, but their overall photocurrent remained constrained by reduced biocatalyst- loading, revealing an inherent trade-off between light availability and biocatalyst-loading capacity. Under these conditions, MP-ITO electrodes delivered a more balanced performance. In conclusion, presented is the most comprehensive systematic study in the structure-activity relationship of electrode architecture to living biophotoelectrochemcial output to our knowledge. References 1. Lawrence, J. M. et al. Rewiring photosynthetic electron transport chains for solar energy conversion. Nature Reviews Bioengineering 1 , 887-905, doi:10.1038/s44222-023-00093-x (2023). 2. Chen, X. et al. 3D-printed hierarchical pillar array electrodes for high-performance semi-artificial photosynthesis. Nat Mater , doi:10.1038/s41563-022-01205-5 (2022). 3. Zhang, J. Z. et al. Photoelectrochemistry of Photosystem II in Vitro vs in Vivo. J Am Chem Soc 140 , 6-9, doi:10.1021/ jacs.7b08563 (2018). 4. Ciornii, D., Kölsch, A., Zouni, A. & Lisdat, F. A precursor-approach in constructing 3D ITO electrodes for the improved performance of photosystem I-cyt c photobioelectrodes. Nanoscale 11 , 15862-15870, doi:10.1039/C9NR04344F (2019). 5. Fang, X. et al. Structure–Activity Relationships of Hierarchical Three-Dimensional Electrodes with Photosystem II for Semiartificial Photosynthesis. Nano Letters 19, 1844-1850, doi:10.1021/acs.nanolett.8b04935 (2019).
P86
© The Author(s), 2025
Made with FlippingBook Learn more on our blog