Room-temperature in situ fabrication and enhanced photocatalytic activity of direct Z-scheme BiOI/g-C3N4 photocatalyst

The direct Z-scheme configuration is particularly beneficial for improving the activity of a photocatalyst by fully exploring the superior oxidation or reduction capability of both coupled components of a heterojunction. Herein, a composite of BiOI quantum dots (QDs) and g-C₃N₄ was fabricated through a precursor in situ transformation method at ambient temperature using a Bi₂O₃/g-C₃N₄ composite as the precursor. By reducing the size of the BiOI to the quantum scale, full and intimate contact between the BiOI and g-C₃N₄ was achieved. In the photocatalytic activity test under visible light, the as-prepared BiOI/g-C₃N₄ composite outperformed the individual BiOI and g-C₃N₄. The Z-scheme electron migration played a key role in the performance enhancement of the composite, because carriers with stronger redox capacity were maintained, while the holes and electrons with weaker redox capacity recombined. This research may also help to elucidate the design of photocatalysts.