*2.3. Production of Electrospun Membranes*

Electrospun non-woven mats with random arrangement of fibers were fabricated using an electrospinning machine (Spinbow s.r.l, Bologna, Italy). Briefly, the electrospinning apparatus was composed of a high voltage power supply, a syringe pump and a glass syringe containing the polymer solution connected to a stainless-steel blunt-ended needle through a polytetrafluoroethylene tube. A grounded plate collector was vertically positioned below the tip of the needle. Electrospinning was performed at room temperature (RT) and relative humidity 40%–50%.

PAN and nylon based membranes were prepared using a stainless-steel blunt needle (inner diameter = 0.84 mm) and collected on a plate collector (25 × 25 cm<sup>2</sup> ). First membranes containing plain TiO<sup>2</sup> and TiO<sup>2</sup> supported Au6Pd<sup>1</sup> nanoparticles, together with a reference polymeric membrane, were prepared. Then, membranes containing unsupported Au6Pd<sup>1</sup> nanoparticles and TiO<sup>2</sup> independently added and just Au6Pd<sup>1</sup> nanoparticles were also produced. The residual solvent in the membranes was removed by thermal treatment at 80 ◦C for 3 h in static air. The mass loss due to the drying was around 1%–3% for all the membranes.

The detailed description of solution preparation and electrospinning conditions for all the produced samples are reported in the Supporting Information section (Tables S1–S3, Figures S1 and S2).
