Comparison of Pt–Cu/C with Benchmark Pt–Co/C: Metal Dissolution and Their Surface Interactions

Abstract

Understanding of less-noble-metal (M) dissolution from Pt-alloy-based oxygen reduction reaction (ORR) electrocatalysts, as well its interaction with Pt surface, is crucial for maximizing their performance. In pursuing this goal, two ORR electrocatalystsa benchmark Pt–Co/C and an in-house designed Pt–Cu/C materialsare investigated. Both are characterized with a range of standard techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM) combined with energy dispersive spectroscopy (EDX) and thin film-rotating disc electrode (TF-RDE) measurements. A special focus is put on combining the latter with a highly sensitive electrochemical flow cell (EFC) online connected to inductively coupled plasma mass spectrometry (ICP-MS) measurements. A combination of standard and novel techniques provides unprecedented insights into the dissolution behavior and dynamics of metals, as well as their subsequent surface interactions and effects on the electrochemical performance. A special focus is devoted to the significance of electrocatalyst activation protocols and their effects on metal dissolution. Distinct differences in the behavior of Pt–Cu and Pt–Co alloys are revealed, which will help develop proper protocols for practical implementation of Pt-alloy electrocatalysts.

A Double‐Passivation Water‐Based Galvanic Displacement Method for Reproducible Gram‐Scale Production of High‐Performance Platinum‐Alloy Electrocatalysts

“…[26] Furthermore,t he PtCu 3 /C-CO analogue exhibits improved performance for ORR in comparison to the Pt/C reference (TEC10E50E, Tanaka Kikinzoku Kogyo; Supporting Information, Figure S18). PtCu 3 /C-CO catalyst exhibits more than five-fold improvement in terms of specific activity at 0.9 V RHE .A sadditionally explored in our recent work, [27,28] the already very active surface of activated PtCu 3 NPs is always to some extent covered with certain amount of Cu impurities.Thus,there remains an untapped potential and still unknown intrinsic activity of the Pt-Cu alloy system, for example by optimizing the binding of oxygen as proposed by Č olić and co-workers. [29] Finally,t he stability of high-loading PtCu 3 /C catalysts on different commercially available carbon supports prepared by the double passivation method (Supporting Information, Figure S8) was evaluated using accelerated degradation tests (ADTs;0 .4-1.2 V RHE ,5 000 cycles,1Vs À1 ).…”

Insight on Single Cell Proton Exchange Membrane Fuel Cell Performance of Pt-Cu/C Cathode

“…This influences the ORR reaction pathway, where a two-electron mechanism can proceed along with the four-electron path. This lowers the overall limiting current density [29]. Overall, the dramatic difference in characteristic ORR parameters directly highlights the importance of further investigation on catalyst pre-treatment.…”

A Double‐Passivation Water‐Based Galvanic Displacement Method for Reproducible Gram‐Scale Production of High‐Performance Platinum‐Alloy Electrocatalysts

“…PtCu 3 /C‐CO catalyst exhibits more than five‐fold improvement in terms of specific activity at 0.9 V RHE . As additionally explored in our recent work, the already very active surface of activated PtCu 3 NPs is always to some extent covered with certain amount of Cu impurities. Thus, there remains an untapped potential and still unknown intrinsic activity of the Pt‐Cu alloy system, for example by optimizing the binding of oxygen as proposed by Čolić and co‐workers …”