Plasmonic Ag/AgCl/NH2-MIL-88B (Fe) inorganic-organic hybridized heterojunction as visible-light-driven photocatalyst for hexavalent chromium reduction

Abstract To effectively photocatalytic removal of Cr (VI), this work focuses on constructing the inorganic-organic hybridized heterojunction composite photocatalyst of Ag/AgCl/NH2-MIL-88B (Fe), where the Ag/AgCl nanoparticles were deposited on the surface of mesoporous NH2-MIL-88B (Fe) via a simple photo-assisted reduction method. The formation of the ternary Ag/AgCl/NH2-MIL-88B (Fe) composite presented more stable and higher photocatalytic reduction performance for Cr (VI) removal than that of MIL-88B (Fe) photocatalyst. Its photo-reduction rate reached to 85.7%, which was ascribed to its high separation and migration efficiency of photogenerated electrons and holes pair. The formed heterojunction structure and surface plasmon resonance effect originated from Ag/AgCl could largely enhance the absorption capacity of visible light, which promotes the excitation of photogenerated electrons, accelerates their transfer, and reduces the recombination rate of electrons and holes. Besides, a possible catalytic mechanism of this reaction is proposed by the photo-induced charge transfer path in the Ag/AgCl/NH2-MIL-88B (Fe) inorganic-organic hybridized system.