A scale-up-led approach to photoelectrochemical water splitting: from nanomaterials optimisation to field testing

George H. Creasey^a^,^b, Arend W. Moelich^c, Craig McGregor^c, Katie Shanks^d, Andreas Kafizas^b, Anna Hankin^a

^aDepartment of Chemical Engineering, Imperial College London, London SW7 2AZ, UK

^bDepartment of Chemistry, Imperial College London, W12 OBZ, UK

^cDepartment of Mechanical and Mechatronic Engineering, Joubert Street, Stellenbosch, 7602, South Africa

^dEnvironment & Sustainability Institute, University of Exeter, Penryn, Cornwall, TR10 9FE, UK

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

E2 Solar fuels and chemicals: from devices to discoveries in unconventional environments

Palma, Spain, 2026 October 26th - 30th

Organizers: Franky Esteban Bedoya Lora, Katharina Brinkert and Anna Hankin

Oral, George H. Creasey, presentation 155
Publication date: 22nd July 2026

Scaling-up photoelectrochemical (PEC) water splitting requires an end-to-end approach that encompasses photoelectrode fabrication, reactor design, optical coupling and operating strategy, yet few studies address these constraints simultaneously.^[1] Our strategy involves a scale-up-led workflow, from materials optimisation in deployment-relevant conditions to field testing and life cycle assessment (LCA).

We developed up-scalable FTO|WO₃|BiVO₄|NiFeOOH photoanodes, mechanically stable under electrolyte flow, sustaining a photocurrent density of 1.75 mA cm^-2 for 24 hours.^[2] Elevated temperature stability tests revealed that a WO₃ seed layer between the FTO and nanostructured WO₃ improves adhesion and mechanical robustness under flow-induced shear stress.^[3]Next, we developed an up-scaled PV-PEC reactor (30 cm² photoanode + Ni cathode + 30 cm² c-Si PV), characterised outdoors on a dual-axis tracking platform. Sunlight was concentrated (up to 4×) laterally onto the photoanode and PV using linear Fresnel lenses and aluminium lightguides, delivering photocurrents up to 77.5 mA.^[4]Returning to the 1 cm² scale, we integrated wide-angle (± 30°) crossed-compound parabolic concentrators (CCPCs, 3.6× optical concentration) with the PEC reactor. We demonstrated broad-angular light concentration, enhancing photocurrent (up to 3×) and enabling simplified solar tracking or stationary configurations, akin to those deployed for solar photovoltaics.^[5,6] Finally, annual hydrogen production was modelled for a theoretical pilot-scale PEC plant. Cradle-to-gate LCA showed that CCPC integration reduces the global warming potential by 21% (from 50.6 to 40.2 kg CO₂-eq. kg^-1H₂), with further reductions with single-axis tracking.^[5]

I shall present results from materials development to field testing, highlighting operability challenges and how optics-coupled modules can enhance performance with reduced balance-of-system complexity.

References:

[1] Moss, B.; Babacan, O; Kafizas, A; Hankin, A. A Review of Inorganic Photoelectrode Developments and Reactor Scale‐Up Challenges for Solar Hydrogen Production. Adv. Energy Mater. 2021, 11(13),

[2] Creasey, G. H.; McCallum, T. W.; Ai, G.; Tam, B.; Rodriguez Acosta, J. W.; Mohammad Yousuf, A.; Fearn, S.; Eisner, F.; Kafizas, A.; Hankin, A. Mechanically and photoelectrochemically stable WO3|BiVO4|NiFeOOH photoanodes synthesised by a scalable chemical vapour deposition method. J. Mater. Chem. A, 2025,13, 11585-11604.

[3] Creasey, G. H.; Kafizas, A.; Hankin, A. Investigating the beneficial effects of a WO3 seed layer on the mechanical and photoelectrochemical stability of WO3|BiVO4|NiFeOOH photoanodes under operational conditions. MRS Commun. 2025, 15, 721-730.

[4] Creasey, G. H.; Moelich, A. W.; Rodriguez Acosta, J. W.; Videira, J. J. H.; Zhu, J.; Halder, S.; McGregor, C.; Kafizas, A.; Hankin, A. Integrating concentrated solar power with a prototype photoelectrochemical reactor. Research Square. 2025.

[5] Creasey, G. H.; Kafizas, A.; Shanks, K.; Hankin, A. Concentration without complexity: enhancing stationary photoelectrochemical reactor performance with diffuse light concentrating optics. ChemRxiv. 2026.

[6] Creasey, G. H.; Kafizas, A.; Hankin, A.; Shanks, K. Controlled quasi-diffuse light characterisation of photoelectrochemical devices and low concentration photovoltaic optics using an integrating sphere. J. Phys. Energy. 2026, 8(2), 026002.

Acknowledgements:

The authors thank the UKRI-EPSRC Solar Chemicals Network (EP/X035301/1) for a Scientific Exchange/Collaboration Award. A. K. thanks the Grantham Institute for Climate Change and the Environment for a pump-priming grant and the EPSRC for a Programme Grant (EP/W017075/1). K. S. thanks the EPSRC for David Clarke Fellowship (EP/V043617/1). A. H. thanks the Department of Chemical Engineering at Imperial College London for an EPSRC DTP PhD scholarship (EP/W524323/1) for G. H. C. and for a lectureship start-up grant.

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