*2.4. Characterization Methods*

X-ray diffraction (XRD) measurements were carried out at room temperature with a Bragg/Brentano diffractometer (X'pertPro PANalytical - Malvern Panalytical Ltd, Malvern, UK) equipped with a fast X'Celerator detector, using a Cu anode as the X-ray source (K<sup>α</sup> = 1.5418 Å). For all samples, diffractograms were recorded in the range 35–44◦ 2θ, counting for 1000 s every 0.1◦ 2θ step. Crystallite size values were calculated using the Scherrer equation from the full width at half maximum intensity measurements.

Scanning electron microscopy (SEM) observations were carried out by using a Leica Cambridge Stereoscan 360 scanning electron microscope (Leica, Cambridge, UK) at an accelerating voltage of 20 kV, on samples sputter-coated with gold. The distribution of fiber diameters was determined through the measurement of about 150 fibers and the results were given as the average diameter ± standard deviation (SD).

Transmission electron microscopy (TEM) observations were carried out by using a FEI Tecnai F20 microscope (Thermo Fisher Scientific, Waltham, MA, USA) equipped with a Schottky emitter and operating at 200 KeV. The fibers were electrospun directly on a TEM copper grid (100 mesh).

Differential scanning calorimetry (DSC) measurements were carried out using a TA Instruments Q100 DSC (Thermal Analysis Instruments, New Castle, PA, USA) equipped with the liquid nitrogen cooling system accessory. DSC scans of electrospun membranes were performed in helium atmosphere at a heating rate of 20 ◦C/min. The glass transition temperature (Tg) was taken at half-height of the glass transition heat capacity step, while the melting temperature (Tm) was taken at the peak maximum of the melting endotherm.

Thermogravimetric analyses (TGA) were carried out using a TGA Q500 thermogravimetric analyzer (TA Instruments, New Castle, DE, USA). Analyses were performed from RT to 700 ◦C, at a heating rate of 10 ◦C/min, under air flow.

The BET specific surface area of each catalyst was determined by N<sup>2</sup> absorption–desorption at liquid N<sup>2</sup> temperature, using a Sorpty 1750 Fison instrument (Micromeritics Instruments Corporation, Norcross, GA, USA). Prior N<sup>2</sup> absorption samples were outgassed at 50 ◦C.
