Scaling Up Electrodes for Photoelectrochemical Water Splitting: Fabrication Process and Performance of 40cm2 LaTiO2N Photoanodes

A scalable process for fabrication of particle-based photoanodes is developed. The electrodes are versatilely made of photocatalytically active semiconductor particles, in this case LaTiO2N, 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 40cm(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 0.1m scale.