The present research
provides a study of carbon-supported intermetallic
Pt-alloy electrocatalysts and assesses their stability against metal
dissolution in relation to the operating temperature and the potential
window using two advanced electrochemical methodologies: (i) the in-house
designed high-temperature disk electrode (HT-DE) methodology as well
as (ii) a modification of the electrochemical flow cell coupled to
an inductively coupled plasma mass spectrometer (EFC-ICP-MS) methodology,
allowing for highly sensitive time- and potential-resolved measurements
of metal dissolution. While the rate of carbon corrosion follows the
Arrhenius law and increases exponentially with temperature, the findings
of the present study contradict the generally accepted hypothesis
that the kinetics of Pt and subsequently the less noble metal dissolution
are supposed to be for the most part unaffected by temperature. On
the contrary, clear evidence is presented that in addition to the
importance of the voltage/potential window, the temperature is one
of the most critical parameters governing the stability of Pt and
thus, in the case of Pt-alloy electrocatalysts, also the ability of
the nanoparticles (NPs) to retain the less noble metal. Lastly, but
also very importantly, results indicate that the rate of Pt redeposition
significantly increases with temperature, which has been the main
reason why mechanistic interpretation of the temperature-dependent
kinetics related to the stability of Pt remained highly speculative
until now.
A fast and facile
pulse combustion (PC) method that allows for
the continuous production of multigram quantities of high-metal-loaded
and highly uniform supported metallic nanoparticles (SMNPs) is presented.
Namely, various metal on carbon (M/C) composites have been prepared
by using only three feedstock components: water, metal–salt,
and the supporting material. The present approach can be elegantly
utilized also for numerous other applications in electrocatalysis,
heterogeneous catalysis, and sensors. In this study, the PC-prepared
M/C composites were used as metal precursors for the Pt NPs deposition
using double passivation with the galvanic displacement method (DP
method). Lastly, by using thin-film rotating disc electrode (TF-RDE)
and gas-diffusion electrode (GDE) methodologies, we show that the
synergistic effects of combining PC technology with the DP method
enable production of superior intermetallic Pt–M electrocatalysts
with an improved oxygen reduction reaction (ORR) performance when
compared to a commercial Pt–Co electrocatalyst for proton exchange
membrane fuel cells (PEMFCs) application.
Carbon-supported Pt-based nanoalloys (CSPtNs) as the oxygen reduction reaction (ORR) electrocatalysts are considered state-of-the-art electrocatalysts for use in proton exchange membrane fuel cells (PEMFCs). Although their ORR activity performance is...
The lack of efficient and durable proton exchange membrane
fuel
cell electrocatalysts for the oxygen reduction reaction is still restraining
the present hydrogen technology. Graphene-based carbon materials have
emerged as a potential solution to replace the existing carbon black
(CB) supports; however, their potential was never fully exploited
as a commercial solution because of their more demanding properties.
Here, a unique and industrially scalable synthesis of platinum-based
electrocatalysts on graphene derivative (GD) supports is presented.
With an innovative approach, highly homogeneous as well as high metal
loaded platinum-alloy (up to 60 wt %) intermetallic catalysts on GDs
are achieved. Accelerated degradation tests show enhanced durability
when compared to the CB-supported analogues including the commercial
benchmark. Additionally, in combination with X-ray photoelectron spectroscopy
Auger characterization and Raman spectroscopy, a clear connection
between the
sp
2
content and structural
defects in carbon materials with the catalyst durability is observed.
Advanced gas diffusion electrode results show that the GD-supported
catalysts exhibit excellent mass activities and possess the properties
necessary to reach high currents if utilized correctly. We show record-high
peak power densities in comparison to the prior best literature on
platinum-based GD-supported materials which is promising information
for future application.
The present research provides a comprehensive study of carbon-supported intermetallic Pt-alloy electrocatalysts and assesses their stability against metal dissolution in relation to the operating temperature and the potential window using two advanced electrochemical methodologies: (i) the in-house designed high-temperature disk electrode (HT-DE) methodology as well as (ii) a modification of the electrochemical flow cell coupled to an inductively coupled plasma mass spectrometer (EFC-ICP-MS), allowing for highly sensitive time- and potential-resolved measurements of metal dissolution. The findings contradict the generally accepted hypothesis that in contrast to the rate of carbon corrosion, which follows the Arrhenius law and increases exponentially with temperature, the kinetics of Pt and subsequently the less noble metal dissolution are supposed to be for the most part unaffected by temperature. On the contrary, clear evidence is presented that in addition to the importance of the voltage/potential window, the temperature is one of the most critical parameters governing the stability of Pt and thus, in the case of Pt-alloy electrocatalysts also the ability of the nanoparticles (NPs) to retain the less noble metal. Lastly, but also very importantly, results indicate that the rate of Pt redeposition significantly increases with temperature, which has been the main reason why mechanistic interpretation of the temperature-dependent kinetics related to the stability of Pt remained highly speculative until now.
A novel PtCo/C based PEMFC electrocatalyst was investigated in real fuel cells under application-relevant conditions. The corresponding MEAs show superior performance compared to reference materials due to more suitable nanoparticle sizes.
The present research provides a comprehensive study of carbon-supported intermetallic Pt-alloy electrocatalysts and assesses their stability against metal dissolution in relation to the operating temperature and the potential window using two advanced electrochemical methodologies: (i) the in-house designed high-temperature disk electrode (HT-DE) methodology as well as (ii) a modification of the electrochemical flow cell coupled to an inductively coupled plasma mass spectrometer (EFC-ICP-MS), allowing for highly sensitive time- and potential-resolved measurements of metal dissolution. The findings contradict the generally accepted hypothesis that in contrast to the rate of carbon corrosion, which follows the Arrhenius law and increases exponentially with temperature, the kinetics of Pt and subsequently the less noble metal dissolution are supposed to be for the most part unaffected by temperature. On the contrary, clear evidence is presented that in addition to the importance of the voltage/potential window, the temperature is one of the most critical parameters governing the stability of Pt and thus, in the case of Pt-alloy electrocatalysts also the ability of the nanoparticles (NPs) to retain the less noble metal. Lastly, but also very importantly, results indicate that the rate of Pt redeposition significantly increases with temperature, which has been the main reason why mechanistic interpretation of the temperature-dependent kinetics related to the stability of Pt remained highly speculative until now.
The design of catalysts with stable and finely dispersed platinum on the carbon support is key in controlling the performance of fuel cells. In the present work, an intermetallic PtCo/C catalyst with a narrow particle size distribution synthesized via double-passivation galvanic displacement is demonstrated. The catalyst exhibits an improved high-current-density performance in single-cell low-temperature fuel cell tests. TEM and XRD confirm a significantly narrowed particle size distribution for the catalyst particles in contrast to commercial benchmark catalysts (Umicore PtCo/C 30 and 50 wt%). Only about 10 % of the mass fraction of PtCo particles show a diameter larger than 8 nm, whereas up to > 35 % for the reference systems. This directly results in a considerable increase in electrochemically active surface area (96 m² g-1 vs. < 70 m² g-1). In addition, a higher fraction of these finely distributed PtCo nanoparticles are anchored on the carbon surface compared to the industrial benchmarks where nanoparticles are located inside the carbon pores. Single-cell tests confirm this finding by a significantly improved performance, especially at high current densities (~ 1 W cm-2 at 0.55 V under H2/air, 50 % RH, 250 kPaabs) and even with lower Pt loading (0.25 mgPt cm-2) compared to the commercial reference (< 0.9 W cm-2 at the same potential and the given conditions) with a higher Pt loading (0.4 mgPt cm-2). Lastly, reducing the cathode catalyst loading from 0.4 to 0.25 mg cm-² resulted in a power density drop at application-relevant 0.7 V of only 4 % for the novel catalyst, compared to the 10 % and 20 % for the Umicore reference catalysts with 30 wt% and 50 wt% PtCo on carbon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.