Upscaling of Temperature-Sensitive Particle Photocatalyst Electrodes: Fully Ambient and Scalable Roll-Press Fabrication of Ta₃N₅ Photoelectrodes on Metal Substrate

The purity of semiconductor films on conductive substrates is proved to be significant in the production of efficient photoelectrodes for water splitting. We apply a scalable roll-press fabrication method to fabricate Ta 3 N 5 /Ti electrodes as a test case under ambient atmosphere. The purity of the Ta 3 N 5 layer can be easily controlled by controlling the purity of the prepared particles. The photoelectrode with a Ta 3 N 5 loading of 2.0 mg cm –2, roll-press force of 10 kN, and Co-Pi cocatalyst generated an onset potential of ca. 0.6 V RHE and a photoanodic current of ca. 3.0 ± 0.2 mA cm –2 (1.23 V RHE ) under artificial sunlight. The results indicate that compaction density and thickness of films are two of the main factors affecting the performance and can be controlled by roll pressing. In addition, the Faradic efficiency of oxygen generation on roll-press fabricated photoanode reached 83% (0.9 V RHE ). Upon further upscaling to an electrode size of 3 × 20 cm 2, the Ta 3 N 5 /Ti photoanode continued to present repeatable performance. The roll-press fabrication method may open an avenue to fabricate large-scale electrodes from temperature-sensitive photocatalysts in solar energy conversion systems because of its high performance and low energy consumption.