A novel photocatalytic platform based on the newly-constructed ternary composites with a double p-n heterojunction for contaminants degradation and bacteria inactivation

Abstract

Visible-light-induced photocatalytic technique is regarded as the most promising approach to tackle environmental pollution. Herein, a novel ternary MIL-88B@COF-200@10%PANI composite with a double p-n heterojunction was firstly synthesized through a step-by-step self-assembly strategy. Current results suggested that bimetallic Fe.Co-MIL-88B displayed excellent photocatalytic activity, and its combination with spherical COF-TPA/TPB effectively promoted separation and transfer of photoinduced carriers. Meanwhile, introducing PANI with π-π conjugated structure acted as a “bridge” of the charge transport could further boost carrier mobility and enhance absorption in visible light region. Benefiting from the formation of double p-n heterojunction, the recombination of photogenerated electron-hole pairs was inhibited effectively, thereby improving the photocatalytic activity. More significantly, in comparison with pristine COF-TPA/TPB, Fe.Co-MIL-88B and PANI, the MIL-88B@COF-200@10%PANI composite not only presented excellent degradation ability for various contaminants, but also exhibited superb sterilization effect for E. coli and S. aureus. The OH, O2−, h+ and e− were main active species in the photocatalytic reaction system, which were responsible for pollutant degradation and bacteria inactivation. Furthermore, it was proved by our experiment results that the separation and transfer routes of photogenerated charge carriers followed a traditional type-II heterojunction mechanism. All in all, this study could provide novel insights for preparation and application of highly efficient photocatalyst in future research.