Simultaneous Degradation of Organic Pollutants and Hydrogen Production Using Dual-Functional NH₂-MIL-125(Ti)/Red Phosphorus Heterostructure under Solar Light Irradiation

Abstract

Herein, NH 2 -MIL-125(Ti)/red phosphorus heterostructures with varying weight percentages of NH 2 -MIL-125(Ti) (NMT) metal−organic framework (MOF) were prepared by using a solvothermal method. The morphological and structural characterization results of the heterostructures depicted strong surface interactions between red phosphorus (RP) and NMT MOF. The photoluminescence and electrochemical impedance spectroscopy studies exhibited improved charge transfer properties of the heterostructures compared to those of RP and NMT MOF. The prepared NMT/red phosphorus heterostructures were tested for the simultaneous photocatalytic degradation of organic pollutants (2,4dinitrophenol, 4-nitrophenol, 2,4,6-trinitrophenol, rhodamine B, methylene blue, and rhodamine 6G) and hydrogen production. The increased separation of charge carriers of the 5% NMT/red phosphorus catalyst over the formed Z-scheme heterojunction led to the achievement of the best activity for the simultaneous process. A maximum H 2 production rate (517.97 μmol h −1 g −1 ) was observed in the rhodamine B dye solution, which was much higher than that in the pure water system (39.76 μmol h −1 g −1 ). This was because, among all of the organic pollutants, rhodamine B dye acted as the best hole scavenger, thus leaving the maximum available photogenerated electrons for H 2 production. Furthermore, optimum degradation efficiency (97.8%) was achieved for methylene blue dye. Moreover, during four cycles of reusability, the photocatalyst showed outstanding H 2 production and degradation stability, making it suitable for use in practical solutions for water and energy issues. Therefore, this work allows for the simultaneous mitigation of wastewater treatment and energy scarcity issues by developing an effective method to prepare Z-scheme heterostructured catalysts with favorable band structures and optimum activity.