Fig. 5: Product formation rates and selectivity.

Rates of formation of H₂ (blue bars), O₂ (green bars), and CO (red bars), as well as selectivity toward CO evolution (black diamonds) for various photocatalysts: a Ag@Cr/Ga₂O₃; b Ag@Cr/Ga₂O₃_Ca_1.1; c Ag@Cr/(1.1 mol%CaO/Ga₂O₃), namely Ga₂O₃ physically mixed with 1.1 mol% of CaO by grinding before loading the Ag@Cr cocatalyst; d Ag@Cr/(30 mol%CaO/Ga₂O₃), which is similar to c except for using 30 mol% of CaO; e Ag@Cr/Ga₂O₃ + 30 mol%CaO, namely Ag@Cr/Ga₂O₃ physically mixed with 30 mol% of CaO by grinding; and f Ag@Cr/Ga₂O₃ and 30 mol% of CaO without mixing before adding into the reaction solution. Schematic structures of the photocatalysts are shown at bottom. Photocatalyst powder: 0.5 g, reaction solution volume: 1.0 L, additive: 0.1 M NaHCO₃, CO₂ flow rate: 30 mL min⁻¹, light source: 400 W high-pressure Hg lamp.