BUSCADOR RECOLECTA

Digital.CSIC. Repositorio Institucional del CSIC

oai:digital.csic.es:10261/361077

Experimental Section: [Materials] 1-Ethyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C2mpyr][TFSI]), 99 % was purchased form IoLiTec. 3,4-Ethylenedioxythiophene (EDOT), 99 % was supplied by Fisher Scientific. Iron (III) chloride hexahydrated (FeCl3·6H2O), 99% was acquired from Sigma Aldrich. All the reagents were used as received with no further purification, apart from [C2mpyr][TFSI], which was dried at 60 ºC under vacuum overnight before use. [Methods] Thermogravimetric analyses were performed under air (25 mL min-1 flow rate) using TGA 8000 Pekin Elmer. The samples were equilibrated at 100 ºC for 20 min and then heated at a rate of 10ºC min-1 in the range of 100-800 ºC. Scanning electron microscope (SEM) measurements were performed on a Hitachi Tabletop Microscope (TM3030 series) at a 15 kV force field, running in a point-by-point scanning mode. The samples were placed on an aluminum holder with doublesided carbon tape and introduced into the SEM chamber. ImageJ was used to measure the pore size distribution in the range of 80-100 pores. The textural properties were characterized by means of N2 adsorption–desorption at −196 °C in a Micromeritics ASAP2020 apparatus. Prior to the analysis, the materials were degassed at 70 °C during 8 h under vacuum at 10−4 mbar. From N2 adsorption–desorption isotherms, the BET area was calculated from the Brunauer–Emmett–Teller equation. Finally, the pore size distribution (PSD) was calculated using the method proposed by Barrett–Joyner–Halenda (BJH) method. The electrochemical characterization was carried out using a VMP-3 potentiostat (Biologic Science Instruments). Scaffolds of Ø=5 mm were employed for the ORR glued with 15 μL of PEDOT:PSS (Clevios PH1000) onto a glassy carbon electrode (Ø=4 mm) as working electrode against platinum wire as reference electrode. Cyclic voltammetry was employed in the range of -0.7 to 0.7 V vs Ag/AgCl at different scan rates to observe the electrochemical response of the different materials using 0.1M KOH electrolyte. Platinum wire was used as counter electrode and Ag/AgCl as reference electrode. The liquid electrolyte was saturated with oxygen bubbling O2 (99.5 %, Air Liquide) for 30 min before running the experiment. [3D scaffold synthesis and characterization] The 3D scaffolds were produced through a multistage process similar to previous reports and as shown in Figure 1.1,2 Sucrose and OIPC ([C2mpyr][TFSI]) were sifted through two sieves with mesh sizes of 250 and 100 μm sequentially. Thereafter, sucrose and OIPC grains in the middle fraction were collected ensuring grain sizes between 250-100 μm. Sieved sucrose (250 mg) and FeCl3·6H2O (20 mg) oxidant were mixed with the aid of a mortar and pestle in presence of 20 (7wt.%), 40 (13 wt.%) or 80 (23 wt.%) mg of OIPC. Finally, 5 μL of Milli-Q water was added in the blend and subsequently mixed until a homogeneous wet material was obtained. The mixture was poured into a hollow plastic cylinder of (Ø=5 mm) in diameter and gently compacted from both sides to form cylindrical-shape templates of 2-3 mm in length. Then, the templates were hung by a thread inside a Schlenk flask. Afterwards, 0.5 mL of EDOT monomer was introduced at the bottom of the Schlenk flask and subsequently left under vacuum for 5 min. VPP was carried out in a bath of 140 ºC overnight. The temperature of the Schlenk flask at the sucrose- OIPC templates was monitored and did not exceed 55 ºC, which ensures the solid state of the OIPC ( = 90 ºC). Once the reaction was 𝑇𝑚 completed, the cylinders were immersed overnight into Milli-Q water to dissolve the sucrose and the excess of oxidant, resulting in self-standing and porous architectures with interconnected microchannels. The scaffolds were cleaned with water and isopropanol for five days in a Soxhlet system until complete removal of iron byproducts. The absence of iron was proved by TGA through the complete weight loss..-- Experimental Section; Figure S1: first derivative from the TGA curves of SC-20, SC-40, and SC-80; Table S2: porosity parameters extracted from physisorption experiments; SBET: specific surface area; VPORE: pore volume; DPORE: equivalent pore diameter (calculated as 4 PORE/SBET); Figure S2: differential scanning calorimetry of C2mpyrTFSI OIPC, SC-20, SC-40, and SC-80 scaffolds at 10 °C min–1; Figure S3: pore size distribution estimated by SEM using ImageJ for 80–100 pores; Figure S4: cyclic voltammograms of PEDOT:PSS, glassy carbon (GC), and platinum (Pt) in N2- and O2-saturated 0.1 M KOH solution; Figure S5: galvanostatic discharge of SC-40 at 0.05 mA cm–2 in 0.1 M KOH electrolyte; electrode mass loading: 47.8 mg cm–2; Figure S6: cyclic voltammograms of SC-40, SC-80, and VPP-CNT in O2-saturated 0.1 M KOH solution at 10 mV s–1.--Under a Cretative Commons license BY 4.0., Experimental Section; Figure S1: first derivative from the TGA curves of SC-20, SC-40, and SC-80; Table S2: porosity parameters extracted from physisorption experiments; SBET: specific surface area; VPORE: pore volume; DPORE: equivalent pore diameter (calculated as 4 PORE/SBET); Figure S2: differential scanning calorimetry of C2mpyrTFSI OIPC, SC-20, SC-40, and SC-80 scaffolds at 10 °C min–1; Figure S3: pore size distribution estimated by SEM using ImageJ for 80–100 pores; Figure S4: cyclic voltammograms of PEDOT:PSS, glassy carbon (GC), and platinum (Pt) in N2- and O2-saturated 0.1 M KOH solution; Figure S5: galvanostatic discharge of SC-40 at 0.05 mA cm–2 in 0.1 M KOH electrolyte; electrode mass loading: 47.8 mg cm–2; Figure S6: cyclic voltammograms of SC-40, SC-80, and VPP-CNT in O2-saturated 0.1 M KOH solution at 10 mV s–1, O.S. thanks the University of the Basque Country (projects COLLAB22/05 and GIU21/033). This research was partly supported by the Australian Research Council Training Centre for Future Energy Storage Technologies (IC180100049) and funded by the Australian Government. This work was supported by an Ikerbasque Research Fellowship from the Basque Government., Peer reviewed