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 Cr(VI) 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 Cr(VI) 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). Cr(VI) reduction rates effectively boosted with increasing FA dosages (0.234–1.170 M) and temperatures (15–55 ℃), but declined with the increase of Cr(VI) 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 H*(ads) 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.