Huge Instability of Pt/C Catalysts in Alkaline Medium

Abstract

International audienceThe stability of carbon-supported electrocatalysts has been largely investigated in acidic electrolytes, but the literature is much scarcer regarding similar stability studies in alkaline medium. Herein, the degradation of Vulcan XC-72-supported platinum nanoparticles (noted Pt/C), a state-of-the-art proton exchange membrane fuel cell electrocatalyst, is investigated in alkaline medium by combining electrochemical measurements and identical location transmission electron microscopy; electrochemical surface area (ECSA) losses were bridged to electrocatalyst morphological changes. The results demonstrate that the degradation in 0.1 M NaOH at 25 degrees C is severe (60% of ECSA loss after only 150 cycles between 0.1 and 1.23 V vs RHE), which is about 3 times worse than in acidic media for this soft accelerated stress test. Severe carbon corrosion has been ruled out according to Raman spectroscopy and X-ray photoelectron spectroscopy measurements, and it seems that the chemistry of the carbon support (in particular, the interface (chemical bounding)) between the Pt nanoparticles and their carbon substrate does play a significant role in the observed degradations

Effects of Pd Nanoparticle Size and Solution Reducer Strength on Pd/C Electrocatalyst Stability in Alkaline Electrolyte

“…28 Interestingly, despite the very mild accelerated stress tests performed (AST -150 cycles between 0.1 and 1.23 V vs. RHE, at 100 mV sec −1 ), the Pt/C catalyst had suffered an extremely severe degradation. The IL-TEM images revealed extensive platinum nanoparticles loss (mostly by detachment from the carbon surface and probably following the destruction of the anchoring surface sites of the Pt nanoparticles at the carbon surface) and non-negligible extent of agglomeration.…”

“…The procedure for the ILTEM characterization is identical to that thoroughly described in Ref. 28. Statistically-relevant particle-size distribution (PSD) histograms were built from the pristine Pd/C electrocatalysts by counting more than ca.…”

Electro-oxidation of a cobalt based steel in LiOH: a non-noble metal based electro-catalyst suitable for durable water-splitting in an acidic milieu

“…Lithium was not determined in the electrolyte (Table S1 †). Degradation of electrocatalysts in acids is well known 34,35,43 after long term polarization at positive potentials.…”

Gold–Copper Aerogels with Intriguing Surface Electronic Modulation as Highly Active and Stable Electrocatalysts for Oxygen Reduction and Borohydride Oxidation

“…[25] Here, the stability of the Au 52 Cu 48 aerogels was first evaluated through an accelerated degradation test (ADT),w hich was performed by applying continuous potential cycling between 0.5 and 1.0 Vw ith as weep rate of 100 mV s À1 in O 2 -saturated 0.1 m KOH solution.C ommercial Pt/C wasu sed as ab aseline catalyst for comparison. [26] After 10 000 cycles,t he Pt/C benchmark catalyst presents am ore negative shifto f3 4mVi nE 1/2 ,a nd its diffusionlimiting current density significantly reduces from 5.87 to 5.15 mA cm À2 (Figure 4b Figure 6a,t he current achieved by the Au 52 Cu 48 aerogels catalyst is maintained at 92 %o fi ts initial value after a4 0000 st est, whereas the current on commercial Pt/C drops to 63 %o ft he initial value. The higher ECSA (103.2 m 2 g Au À1 ), SA (0.891 mA cm À2 ), and MA (0.920 Amg -1 Au )a re maintained after 10 000 potential cycles,e xhibiting decreases of only 2.6, 1.7, and 4.2 %c omparedt ot he corresponding initial values, respectively ( Figure 5a nd Ta ble S2).…”