A polymer-catalyst assembly includes polarized polymeric nanofibers retaining a plurality of catalytic metallic nanoparticles. A method of making the polarized polymer-catalyst assembly may include providing a fiber mat having polymeric nanofibers retaining a plurality of catalytic metallic nanoparticles, stretching the fiber mat in a uniaxial direction, simultaneous with the step of stretching, thermally heating the fiber mat, simultaneous with the steps of stretching and thermally heating, subjecting the fiber mat to an electric field, whereby the simultaneous steps of stretching, thermally heating, and subjecting thereby form a polarized fiber mat.