Increasing hydrogen and oxygen evolution rates using a directly connected composite photocatalyst, zinc rhodium oxide and silver vanadium oxide, by changing water-splitting reaction conditions

Abstract The effects of reaction vessel scale and argon (Ar) gas pressure on the overall water splitting catalyzed by directly connected silver vanadate (Ag2V4O11) and zinc rhodium oxide (ZnRh2O4), i.e., Ag2V4O11/ZnRh2O4, were systematically investigated. Scaling up the reaction vessel 10-fold resulted in marked 30-fold increases in hydrogen (H2) and oxygen (O2) evolution rates, which were attributed to improved light utilization. Lowering the base Ar pressure to 10 kPa further boosted kinetics, achieving an apparent quantum efficiency (AQE) of 0.12% at 850 nm. These results demonstrate that optimizing reactor scale and gas pressure is an effective strategy for enhancing the photocatalytic water-splitting performance.