Room-temperature in situ fabrication of Bi 2 O 3 /g-C 3 N 4 direct Z-scheme photocatalyst with enhanced photocatalytic activity

Abstract Constructing direct Z-scheme heterojunction is an effective approach to separating photogenerated charge carriers and improving the activity of semiconductor photocatalysts. Herein, a composite of bismuth(III) oxide (Bi 2 O 3 ) and graphitic carbon nitride (g-C 3 N 4 ) was in situ fabricated at room temperature by photoreductive deposition of Bi 3+ and subsequent air-oxidation of the resultant metallic Bi. Quantum-sized ω-Bi 2 O 3 nanoparticles approximately 6 nm in diameter were uniformly distributed on the surface of mesoporous g-C 3 N 4 . The as-prepared Bi 2 O 3 /g-C 3 N 4 composite exhibited higher photocatalytic activity than pure Bi 2 O 3 and g-C 3 N 4 for photocatalytic degradation of phenol under visible light. Reactive species trapping experiments revealed that superoxide radicals and photogenerated holes played important roles in the photocatalytic degradation of phenol. The enhanced photocatalytic activity, identification of reactive species and higher rate of charge carrier recombination (as indicated by stronger photoluminescence intensity) collectively suggest that the charge migration within the Bi 2 O 3 /g-C 3 N 4 composite followed a Z-scheme mechanism. Photogenerated electrons on the conduction band of Bi 2 O 3 migrate to the valence band of g-C 3 N 4 and combine with photogenerated holes therein. At the cost of these less reactive charge carriers, the Z-scheme heterojunction enables efficient charge separation, while preserving the photogenerated electrons and holes with stronger redox abilities, which is beneficial for enhanced photocatalytic activity.