Metal-free 2D/2D heterostructured photocatalyst of black phosphorus/covalent triazine-based frameworks for water splitting and pollutant degradation

The design of metal-free photocatalysts has drawn considerable attention in photocatalysis due to the merits of low cost, sustainability, and recyclability without releasing toxic metals from photocorrosion. As an emerging metal-free photocatalyst, the covalent triazine-based framework (CTF) has stimulated great research interest in photochemical water splitting. Nevertheless, the poor separation efficiency of photogenerated charge carriers and limited light absorption ability of the CTF hinders its photocatalytic performance. Herein, a metal-free 2D/2D heterostructured photocatalyst composed of black phosphorus (BP) and a CTF is prepared by a facile liquid exfoliation approach and applied to photocatalytic water splitting and pollutant degradation. Compared to the CTF, the BP/CTF photocatalyst exhibits a two-fold increase in the hydrogen evolution rate and a nine-fold increase in the degradation rate constant of rhodamine B (RhB) with visible light illumination, mainly due to the enhanced photoinduced charge carrier separation and strengthened visible light harvesting ability. This work provides sustainable approaches for the synthesis and construction of highly-reactive and metal-free photocatalysts for solar-to-chemical energy conversion.