Enhanced charge separation in dual Z-scheme Au decorated LaFeO3-g-C3N4-BiFeO3 system for efficient H2 production

Abstract

The artificial Z-scheme system that mimics natural photosynthesis is encompassed of two semiconductors which generates two sets of charge carriers at different locations under solar irradiation. Researchers are trying to improve the efficacy of these systems by engineering highly stable redox couples, enhancing their light absorption capability, and discovering new cocatalysts. Herein, we report the fabrication of Au decorated LaFeO3-g-C3N4-BiFeO3 (Au/LFO-CN-BFO) catalyst as dual Z-scheme system for photocatalytic water splitting reactions. The photocatalytic performances of Au/LFO-CN-BFO, LFO-CN-BFO, LaFeO3, g-C3N4 and BiFeO3 were compared and the mechanism on the symmetric double Z-scheme Au/LFO-CN-BFO photocatalytic system was proposed. The results display that Au/LFO-CN-BFO has more superior photocatalytic performance compared to its counter parts (LaFeO3, g-C3N4 and BiFeO3), which is due to the symmetric double Z-scheme nature of photocatalyst. The as-fabricated Au/LFO-CN-BFO photocatalyst reveals high performance for photocatalytic water reduction to evolve H2 (i.e., 698.4 µmol h-1g−1) under visible light irradiation (λ ≥ 420 nm), which is far greater compared to that of its counterparts. As confirmed from various observations, the improved H2 evolution performance of the dual Z-scheme system is accredited to the improved light absorption and significantly promoted charge carrier’s separation. The design of this highly efficient dual Z-scheme composite photocatalyst would trigger the development of new artificial Z-scheme scheme systems that will solve the energy and associated environmental issues.