1. Αποθετήριο Παραδοτέων Υποτρόφων Δράσεων ΕΣΠΑ Τριτοβάθμιας Εκπαίδευσης 2017-2023
2. Όλο το Αποθετήριο
3. Ερευνητικές ομάδες

Τύπος:	Ανακοίνωση σε συνέδριο
Τίτλος:	Pt-based bimetallic electrocatalysts for hydrogen oxidation reaction in alkaline medium
Συγγραφέας:	[EL] Μπάμπος, Γεώργιος[EN] Bampos, Georgios [EL] Σπηλιόπουλος, Αριστόβουλος[EN] Spiliopoulos, Aristovoulos [EL] Μπεμπέλης, Συμεών[EN] Bebelis, Symeon
Ημερομηνία:	Σεπ-2023
Περίληψη:	A major advantage of anion alkaline exchange membrane fuel cells (AAEMFCs) compared to proton exchange membrane fuel cells (PEMFCs) is the use of electrocatalysts with, relatively, low Pt loading at the cathodic oxygen reduction reaction (ORR) due to the repaid ORR kinetics in alkaline environment [1]. However, the kinetics of anodic hydrogen oxidation reaction (HOR) in alkaline environment over commercial Pt/C electrocatalysts is ca. two orders of magnitude slower than that exhibited in acidic environment requiring high Pt loading in order to be catalyzed effectively [2]. The partial substitution of Pt by another transition metal in electrocatalysts for HOR in alkaline media could result in reduction of the cost of the electrocatalyst and a potential increase of the electrocatalytic activity due to alterations of the electronic properties of the active metal phase [3]. Towards the direction of developing low-cost and active electrocatalysts for HOR, in the present work a series of carbon black (Vulcan XC72R, Cabot) bimetallic Pt-M (Μ: Ag, Co, Cu, Fe, Ni, Ru, Sn, Zn)/C electrocatalysts with a total metal loading equal to 10 wt.% and a Pt-M atomic ratio equal to 3:1 were synthesized via the wet impregnation method (w.i.) and reduced at 300 oC under H2 flow for 2h [4]. A monometallic 10 wt.% Pt/C electrocatalyst also synthesized via w.i. and reduced at 300 oC was used as reference materials. The synthesized electrocatalysts were characterized as it concerns their specific surface area (SSA) and structure employing BET method and X-ray diffraction (XRD) technique, respectively. The as prepared powders were investigated towards their HOR activity in alkaline environment using the rotating disk electrode (RDE) technique [5] in H2 saturated 0.1 M KOH solution. Prior to the electrocatalytic activity measurements, the electrochemically active surface area (ECSA) was determined for each electrocatalyst by the electrochemical oxidation of a pre-adsorbed monolayer CO (CO stripping) technique [6]. The SSAs of the catalyst powders ranged between 91 m2 g-1 (8.3 wt.% Pt – 1.7 wt. % Sn/C) and 170 m2 g-1 (9.0 wt.% Pt – 1.0 wt.% Zn/C). The deposition of the metal phase on the carbon support resulted in a significant decrease of its SSA (216 m2 g-1) which could be attributed to blockage of the pores of the support by metal particles [4]. The presence of alloy phase as obtained by analysis of the XRD spectra was identified only in the case of the 9.0 wt.% Pt – 1.0 wt.% Zn/C catalyst (Pt3Zn) whereas in the rest samples crystallographic peaks attributed to metallic Pt were observed. The highest ECSA (88 m2 gPt-1) was exhibited by the 10 wt.% Pt/C and 9.0 wt.% Pt – 1.0 wt.% Zn/C electrocatalysts whereas the smallest ECSA by the 8.3 wt.% Pt – 1.7 wt.% Sn/C (11 m2 gPt-1). The 8.3 wt.% Pt – 1.7 wt.% Sn/C exhibited the highest specific activity (S.A. mA cmPt-2) towards and mass activity (M.A., A gPt-1) towards HOR over the entire examined potential range. The monometallic 10 wt.% Pt/C electrocatalyst was less active than the bimetallic electrocatalysts with the exception of 9.1 wt.% Pt – 0.9 wt.% Fe/C for applied potential close to open circuit potential. For quantitative comparison, at -0.8 V vs. Ag/AgCl (0.16 V vs. RHE) applied potential value the S.A. and M.A. of the 8.3 wt.% Pt – 1.7 wt.% Sn/C electrocatalyst were 98 mA cmPt-2 and 9520 A gPt-1, respectively, whereas that of 10 wt.% Pt/Cwas equal to 0.2 mA cm-2 and 158 A gPt-1. This behavior can be attributed to: (a) the higher oxophilicity of M compared to Pt, which favors OHad adsorption on the M surface with a consequent increase in the availability of Pt surface active sites for hydrogen adsorption, and (b) to decrease in the energy of the d-band center of Pt, with a consequent decrease in the binding energy of the Had species. Both of the former effects lead to an increase in the HOR rate, based on its mechanism [7-8]. [1] Varcoe, J.R., Slade, R.C.T. (2005). Fuel Cells. 5: 187–200. [2] Sheng, W., Gasteiger, H.A., Shao-Horn, Y. (2010). J. Electrochem. Soc. 157: B1529. [3] Tang, W., Henkelman, G. (2009). J. Chem. Phys. 130: 194504. [4] Bampos, G., Bebelis S., Kondarides, D.I., Verykios, X. (2017). Top. Catal. 60: 1260-1273. [5] Schmidt, J., Gasteiger, H.A., Stäb, G. D., Urban, P.M., Kolb, D.M., Behm, R.J. (1998). J. Electrochem. Soc. 145:2354-2358. [6] Bampos, G., Sygelloy, L., Bebelis, S. (2020). Catal. Today 355: 685-67. [7] Bakos, I., Paszternak, A., Zitoun, D. (2015). Electrochim. Acta. 176: 1074-1082. [8] Henning, S., Herranz, J., Gasteiger, H.A. (2014). J. Electrochem. Soc. 162: F178-F189.
Γλώσσα:	Αγγλικά
Τόπος δημοσίευσης:	Lyon, France
Σελίδες:	1
Θεματική κατηγορία:	[EL] Χημική μηχανική[EN] Chemical Engineering
Κάτοχος πνευματικών δικαιωμάτων:	© The Author(s) 2023
Όνομα εκδήλωσης:	74th Annual Meeting of the International Society of Electrochemistry
Τοποθεσία εκδήλωσης:	Lyon, France
Ημ/νία έναρξης εκδήλωσης:	03/09/2023
Ημ/νία λήξης εκδήλωσης:	08/09/2023
Σημειώσεις:	https://annual74.ise-online.org/img_conf/ISE-AM74-program_web.pdf This research was funded in the frame of the project “Perovskitic electrocatalysts for integrated systems of microbial electrolysis cells and anion exchange membrane fuel cells (Acronym: PERFORMANCE, project code: 82242)”, which was supported by the 3rd Call of Hellenic Foundation of Research and Innovation (H.F.R.I.) Research Projects for the support of Post-doctoral Researchers (fellowship of Dr. G. Bampos).
Εμφανίζεται στις συλλογές:	Ερευνητικές ομάδες