Weakness-complementing Z-scheme black phosphorus/TiO2 heterojunction with efficient charge separation and photocatalytic overall water splitting activity

The photocatalytic efficiency of Black P is limited by its rapid carrier recombination and poor oxidation ability. In contrast, the photocatalytic efficiency of TiO 2 is limited by its rapid carrier recombination and poor visible light absorption capability. Given this, coupling Black P with TiO 2 to construct a heterojunction achieves complementary weaknesses. With an effective photocatalytic water splitting activity, Black P/TiO 2 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 TiO 2 . 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.