How to appropriately assess the oxygen reduction reaction activity of platinum group metal catalysts with rotating disk electrode

Abstract

Summary The sluggish oxygen reduction reaction (ORR) has becoming the bottleneck of largescale implementation of proton exchange membrane fuel cells. However, when it comes to the ORR activity assessing of platinum group metals (PGMs) with rotating disk electrode, the corresponding potential conversion vs. reversible hydrogen electrode, test protocols, and activity calculation processes are still in chaos in many published literatures. In this work, two standard calculation processes for PGM ORR activities are demonstrated, followed by a specification for the usage of reference electrodes. Then a 4-fold discrepancy in ORR activities obtained via different test protocols is found for the same Pt/C, and an average adsorption model and the “coverage effects” are proposed to illustrate the hysteresis loop between negative and positive-going ORR polarization plots. Finally, four motions over appropriate assessment of PGM ORR activity are emphasized, hoping to bring a fair communication platform for researchers from different groups.

Atomically Ordered Pt5La Nanoparticles as Electrocatalysts for the Oxygen Reduction Reaction

“…Prior to the ORR test, the electrocatalysts were treated by repeating a potential scan 300 times at 100 mV s –1 over the potential range of 0.05–1.1 V (vs RHE) in an Ar-saturated 0.1 M HClO 4 solution. The electrochemical surface areas (ECSAs) of TKK Pt NPs/CB, D-PtLa NPs/CB, and O-Pt 5 La NPs/CB before the ORR test were 41.1, 66.9, and 47.1 m 2 g –1 (see Figure S5), respectively, as determined from their hydrogen desorption peaks. , The ORR limiting current density was approximately −5.5 mA cm –2 , indicating that a four-electron transfer occurred on the electrocatalyst surface. , In addition, the number of electrons transferred for the ORR at O-Pt 5 La NPs/CB was determined to be 4.0 from the Levich analysis at +0.6 V (vs RHE), as shown in Figure S6. Figure B compares the mass (MA) and specific (SA) activities of TKK Pt NPs/CB, D-PtLa NPs/CB, and O-Pt 5 La NPs/CB.…”

Stability of Platinum‐Group‐Metal‐Based Electrocatalysts in Proton Exchange Membrane Fuel Cells

“…The SA or MA, along with the ECSA, is hence determined at various stages of the stress test. [150,151] As for the assessment of ECSA, it is worth noting that diversified methods can be used to determine the surface area. For instance, CO stripping is encouraged to be used to track the ECSA change of Pt/C in the stability test.…”

Microwave Heating of Nanocrystals for Rapid, Low-Aggregation Intermetallic Phase Transformations

“…Electrochemical measurements were performed using standard protocols. − Data were collected on a potentiostat (Epsilon, Bioanalytical Systems Inc.) with a three-electrode system consisting of a glassy carbon working electrode (6 mm diameter), an Ag/AgCl reference electrode in 3 M KCl, and a Pt Coil auxiliary electrode. All potentials collected during the testing were converted in reference to a reversible hydrogen electrode (RHE).…”

“…The electrochemical stability data and ORR activity is shown in Figure A–F. The electrochemical testing methods used here follow standard practices. ,− To test for stability, the samples were cycled between 0.6 and 1.0 V vs RHE in N 2 saturated 0.1 M HClO 4 , with Cyclic Voltammetry (CV) curves taken after 50 cycles at the beginning-of-life (BOL), 5000, and 25 000 cycles, shown in Figure A–C for the A1, Therm-L1 0 , and MW-L1 0 samples, respectively. The ECSA was determined from the CV curves shown in Figure A–C using hydrogen underpotential deposition measurements .…”