Weakness-complementing Z-scheme black phosphorus/TiO₂ heterojunction with efficient charge separation and...

The photocatalytic efficiency of Black P is limited by its rapid carrier recombination and poor oxidation ability. In contrast, the photocatalytic efficiency of TiO₂ is limited by its rapid carrier recombination and poor visible light absorption capability. Given this, coupling Black P with TiO₂ to construct a heterojunction achieves complementary weaknesses. With an effective photocatalytic water splitting activity, Black P/TiO₂ produces hydrogen at a rate of 139.50 μmol h^-1 g^-1 under visible light, which is 4.73 times more than Black P's. The main reason for the big increase in photocatalytic activity is that a Z-scheme heterojunction forms between Black P and TiO₂. The internal built-in electric field promotes the recombination of electrons with low reduction potential and holes with low oxidation potential, achieving spatial separation of photogenerated electrons with high reduction potential and holes with high oxidation potential. This spatial separation endows the heterojunction photocatalyst with excellent redox capabilities.