Nonprecious bimetallic (Mo, Fe)-N/C nanostructures loaded on PVDF membrane for toxic CrVI reduction from water

Nonprecious bimetallic molybdenum and iron embedded into N-doped carbon (MoFe-NC) hybrids were designed and fabricated by pyrolysis of mixed precursors and then immobilized on poly (vinylidene fluoride) (PVDF) films via a phase inversion process to obtain novel catalytic membranes (MoFe-NC@PVDF) for toxic Cr-VI reduction. The catalytic membranes are highly active for aqueous Cr-VI reduction using formic acid (FA) as a sacrificial electron donor under mild conditions. The results demonstrated that the parameters of synthesis process can efficiently adjust the morphology and textural properties of the as-synthesized MoFe-NC@PVDF membrane, and thus have a significant impact on the catalytic behavior. Cr-VI reduction rates significantly increased with increasing FA concentrations (0.234-0.936 M) and reaction temperature (5-35.), but declined with the increase of Cr-VI concentrations (5-40 mg/L) and pH values of solution (1.87-4.62). Mo-Nx, Fe-Nx, and C-Nx are the active sites, boosting the dissociation of FA molecules into active H* species for effective catalytic reduction of Cr-VI. The catalytic PVDF membrane exhibited distinct porous structure and numerous interaction sites, which not only stabilized metallic nanoparticles, but also promoted mass transfer across the membrane. This cost-effective catalytic membrane provides a new approach toward the treatment of Cr-VI-containing water.