Scaling Up Electrodes for Photoelectrochemical Water Splitting: Fabrication Process and Performance of 40 cm²LaTiO₂N Photoanodes

Abstract

A scalable process for fabrication of particle‐based photoanodes is developed. The electrodes are versatilely made of photocatalytically active semiconductor particles, in this case LaTiO 2 N, and optionally coated with cocatalysts and protecting components, all immobilized on a conducting substrate. The involved fabrication steps are restricted to scalable processes such as electrophoretic deposition, annealing in air, and dip coating. Special care is taken to ensure efficient charge transport in‐between particles and to the substrate by incorporating conducting connectors. By adapting the fabrication steps, the electrode geometrical dimension is increased from the size of a typical lab electrode of 1 to 40 cm 2 . The quality of the scale‐up process is characterized by comparing the photoanodes in terms of thickness, light‐absorption properties, and morphology. For several compositions, the electrochemical performance of both electrode sizes is assessed by measuring the photocurrents and faradaic efficiencies. The comparison revealed a complex upscaling behavior and showed that the photoelectrode size affects performance already on the 0.1 m scale.

Emergent Degradation Phenomena Demonstrated on Resilient, Flexible, and Scalable Integrated Photoelectrochemical Cells

“…The good stability is in part enabled by feeding pure water, instead of the strongly acidic or basic electrolytes commonly used in (I)PEC devices. [ 15,16,19,30–35 ] While PEC devices often suffer from significant performance losses during scale‐up (Table S2, Supporting Information), [ 33,35–41 ] our initial assessments suggest that this IPEC device design is scalable without large performance losses and that the results are reproducible. Furthermore, we analyze the material costs of the device, indicating that light concentration may be necessary to offset today's high costs of low‐volume III–V PVs and to achieve the DOE cost target (Tables S3 and S4, Supporting Information).…”

Mitigating voltage losses in photoelectrochemical cell scale-up

“…Finally, we note that our simulation results, which show non-linearity dependence between the electrode area and the total scale-up associated losses, qualitatively agree with experimental results reported in the literature. 21,23,55 Further experiments usingfor examplein situ pH monitoring 56,57 and particle image velocimetry 58 are needed to quantitatively validate our ndings.…”

“…Most reported devices have an area of smaller than 1 cm 2 , and only a handful demonstrated areas larger than 10 cm 2 . 2,[19][20][21][22][23] Moreover, these large-area devices tend to deliver much lower STH efficiency (by up to a factor of $5) as compared to their small-area equivalent. 2 For example, it was recently reported that while small-area (0.24 cm 2 ) BiVO 4 -based tandem device delivers STH efficiency of $6%, the large-area (50 cm 2 ) equivalent is only capable of delivering an STH efficiency of $2%.…”

Demonstration of a 50 cm2 BiVO4 tandem photoelectrochemical-photovoltaic water splitting device

“…31 These types of losses have been observed elsewhere in the scale up of metal oxide photoanodes. 32 However, no detailed analysis of the underlying reasons for the lower photocurrent densities for the large area photoanodes (25 and 300 cm 2 ) as compared to the smaller area (1 cm 2 ) was made.…”