Suppressing Platinum Electrocatalyst Degradation via a High-Surface-Area Organic Matrix Support

Milutin Smiljanić; Marjan Bele; Léonard Jean Moriau; John Fredy Vélez Santa; Svit Menart; Martin Šala; Armin Hrnjić; Primož Jovanovič; Francisco Ruiz-Zepeda; Miran Gaberšček; Nejc Hodnik

doi:10.1021/acsomega.1c06028

Suppressing Platinum Electrocatalyst Degradation via a High-Surface-Area Organic Matrix Support

ACS Omega. 2022 Jan 19;7(4):3540-3548. doi: 10.1021/acsomega.1c06028. eCollection 2022 Feb 1.

Authors

Milutin Smiljanić^{1

2}, Marjan Bele¹, Léonard Jean Moriau^{1

3}, John Fredy Vélez Santa^{1

4}, Svit Menart¹, Martin Šala⁵, Armin Hrnjić¹, Primož Jovanovič¹, Francisco Ruiz-Zepeda¹, Miran Gaberšček^{1

6}, Nejc Hodnik^{1

3

7}

Affiliations

¹ Department of Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
² Laboratory for Atomic Physics, Institute for Nuclear Sciences Vinča, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade, Serbia.
³ Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia.
⁴ Materials Physics Center (CSIC-UPV/EHU), Paseo Manuel de Lardizabal 5, Donostia-San Sebastián 20018, Spain.
⁵ Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
⁶ Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
⁷ University of Nova Gorica, Vipavska 13, 5000 Nova Gorica, Slovenia.

Abstract

Degradation of carbon-supported Pt nanocatalysts in fuel cells and electrolyzers hinders widespread commercialization of these green technologies. Transition between oxidized and reduced states of Pt during fast potential spikes triggers significant Pt dissolution. Therefore, designing Pt-based catalysts able to withstand such conditions is of critical importance. We report here on a strategy to suppress Pt dissolution by using an organic matrix tris(aza)pentacene (TAP) as an alternative support material for Pt. The major benefit of TAP is its potential-dependent conductivity in aqueous media, which was directly evidenced by electrochemical impedance spectroscopy. At potentials below ∼0.45 V_RHE, TAP is protonated and its conductivity is improved, which enables supported Pt to run hydrogen reactions. At potentials corresponding to Pt oxidation/reduction (>∼0.45 V_RHE), TAP is deprotonated and its conductivity is restricted. Tunable conductivity of TAP enhanced the durability of the Pt/TAP with respect to Pt/C when these two materials were subjected to the same degradation protocol (0.1 M HClO₄ electrolyte, 3000 voltammetric scans, 1 V/s, 0.05-1.4 V_RHE). The exceptional stability of Pt/TAP composite on a nanoscale level was confirmed by identical location TEM imaging before and after the used degradation protocol. Suppression of transient Pt dissolution from Pt/TAP with respect to the Pt/C benchmark was directly measured in a setup consisting of an electrochemical flow cell connected to inductively coupled plasma-mass spectrometry.