Zn-MoS2 nanocatalysts anchored in porous membrane for accelerated catalytic conversion of water contaminants

Abstract

A series of Zn-MoS2 heterostructures were fabricated via a thermal-treatment method, and then anchored in polyvinylidene fluoride (PVDF) to yield novel catalytic membranes (Zn-MoS2@PVDF) by the phase inversion technique for enabling CrVI reduction. The SEM image showed that ZnS nanoparticles homogeneously coated on the MoS2 surface assembled in flower-like agglomerations. Zn-MoS2@PVDF exhibited unprecedented activity of CrVI reduction using formic acid (FA) as the reductant, with a high rate constant (k = 0.033 min−1) and low activation energy (Ea = 38.8 kJ mol−1). CrVI reduction rates effectively boosted with increasing FA dosages (0.234–1.170 M) and temperatures (15–55 ℃), but declined with the increase of CrVI concentrations (5–25 mg/L), solution pHs (2.03–5.11) and inorganic salts. The excellent performance of Zn-MoS2@PVDF originated from the synergistic effect of the unique composition and electronic structure of the membranes. The strong electronic interactions of ZnS and MoS2 made an insignificant contribution to generate intermediate Hads* and released molecular hydrogen. Rich porosity of PVDF membranes might not only afford a uniform dispersion of the Zn-MoS2 NPs, but also decrease mass transport resistance and provide an enlarged catalytic surface area. These outstanding characteristics indicate the potential applicability of Zn-MoS2@PVDF membranes for the remediation of heavy metal pollution.