Superior photocatalytic and electrochemical activity of the MoSe2 modified ZIF-67 for the reduction and detection of Cr (VI)

Abstract

The removal and detection of heavy metals from wastewater have proven to be challenging due to the limitations of the materials and technologies. Therefore, in this work, we have synthesized novel Z-scheme-based MoSe2-modified ZIF-67 by a two-step method and tested it for environmental safety by electrochemical detection and photocatalytic reduction of carcinogenic heavy metal pollutant (hexavalent chromium (Cr (VI)). The nanosheets and polyhedrons-like morphology of MoSe2 and ZIF-67 were confirmed using Field emission scanning electron microscope (FESEM) and High-resolution transmission electron microscope (HRTEM), respectively. The nanocomposite exhibited superior activity for photocatalytic reduction (∼89% within 30 min) towards Cr (VI) along with the detection (LOD-0.01 µM) with high stability. The superior activity of the MZ67 nanocomposite is attributed to enhanced recombination time (4.65 ns) with respect to pristine ZIF-67 (1.21 ns) as observed from time-correlated single photon counting (TCSPC) studies. The scavenger test and electron paramagnetic resonance (EPR) studies confirmed the Z-scheme of the nanocomposite. The electrochemical sensing for Cr (VI) combined with the photocatalytic reduction, tends to provide a trustworthy tool for wastewater management.