Assembling Bi2MoO6/Ru/g-C3N4 for Highly Effective Oxygen Generation from Water Splitting under Visible-Light Irradiation

Water oxidation is a kinetically challenging reaction for photocatalytic overall water splitting. Producing one molecule of O2 will consume four electrons, so it is an extremely difficult obstacle for researchers. Here, a Bi2MoO6/Ru/g-C3N4 composite was obtained by a gentle hydrothermal method, which could oxidize water into O2 highly efficiently. The optimal O2 production reached 328.34 μmol·g–1·h–1 under visible light irradiation. Moreover, the catalyst presented excellent stability, as shown by a still sustentative 91.4% photocatalytic activity and invariant textural structure after seven recycling tests. The ternary material had the smallest resistance, which indicated that it has a good photoelectron conductive tunnel, and a rapid transfer route is proposed through Bi2MoO6 → Ru → g-C3N4 → NaIO3 (electron acceptor). The massive holes (h+) with high oxidative potential are surely enriched due to the quick electron migration, being fit for a large promotion of the multiple-electron water oxidative proceedings. Therefore, the metallic Ru provided a powerful bridge for efficient transfer of the interface electrons which could be beneficial to spatial separation of photoexcited carriers without the loss of the high redox capacity. Finally, it is proposed that the Ru-assisted electron transport and constituent synergy in Bi2MoO6/Ru/g-C3N4 composite play crucial roles to its enhanced light utilization, efficient photoelectric conversion property, and high-producing oxygen capability.