Electrochemical Adsorption on Pt Nanoparticles in Alkaline Solution Observed Using In Situ High Energy Resolution X-ray Absorption Spectroscopy

Kusano, Shogo; Matsumura, Daiju; Ishii, Kenji; Tanaka, Hiroyuki; Мizuki, J.

doi:10.3390/nano9040642

Cited by 11 publications

(18 citation statements)

References 34 publications

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“…Based on the evolution of fitting parameters with potential, it is convenient to divide the potential range into three sections: hydrogen chemisorption (0–0.3 V), oxygen chemisorption (0.3–0.96 V), and Pt oxide formation (>0.96 V). Kusano et al conducted similar experiments on 2–4 nm Pt NPs in alkaline media and observed that the evolution of the XANES profiles also depended on whether N 2 or O 2 was flowing . They used the change of the XANES signal Δμ to characterize the change of HERFD-XAS.…”

Section: Operando and In Situ Characterizationsmentioning

confidence: 99%

Section: Operando and In Situ Characterizationsmentioning

confidence: 99%

“…Kusano et al conducted similar experiments on 2−4 nm Pt NPs in alkaline media and observed that the evolution of the XANES profiles also depended on whether N 2 or O 2 was flowing. 1013 They used the change of the XANES signal Δμ to characterize the change of HERFD-XAS. This method first selects the XANES profile at 0.34 V as a standard and plots the deviation of XANES from the standard, denoted as Δμ, at other potentials (Figure 72F).…”

Section: Operando and In Situ Characterizationsmentioning

confidence: 99%

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Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition of the global energy landscape from fossil fuels to renewable energy. Here, we present a comprehensive review of the fundamentals of electrocatalysis in alkaline media and applications in alkaline-based energy technologies, particularly alkaline fuel cells and water electrolyzers. Anion exchange (alkaline) membrane fuel cells (AEMFCs) enable the use of nonprecious electrocatalysts for the sluggish oxygen reduction reaction (ORR), relative to proton exchange membrane fuel cells (PEMFCs), which require Pt-based electrocatalysts. However, the hydrogen oxidation reaction (HOR) kinetics is significantly slower in alkaline media than in acidic media. Understanding these phenomena requires applying theoretical and experimental methods to unravel molecularlevel thermodynamics and kinetics of hydrogen and oxygen electrocatalysis and, particularly, the proton-coupled electron transfer (PCET) process that takes place in a proton-deficient alkaline media. Extensive electrochemical and spectroscopic studies, on single-crystal Pt and metal oxides, have contributed to the development of activity descriptors, as well as the identification of the nature of active sites, and the rate-determining steps of the HOR and ORR. Among these, the structure and reactivity of interfacial water serve as key potential and pH-dependent kinetic factors that are helping elucidate the origins of the HOR and ORR activity differences in acids and bases. Additionally, deliberately modulating and controlling catalyst−support interactions have provided valuable insights for enhancing catalyst accessibility and durability during operation. The design and synthesis of highly conductive and durable alkaline membranes/ionomers have enabled AEMFCs to reach initial performance metrics equal to or higher than those of PEMFCs. We emphasize the importance of using membrane electrode assemblies (MEAs) to integrate the often separately pursued/optimized electrocatalyst/support and membranes/ionomer components. Operando/in situ methods, at multiscales, and ab initio simulations provide a mechanistic understanding of electron, ion, and mass transport at catalyst/ionomer/membrane interfaces and the necessary guidance to achieve fuel cell operation in air over thousands of hours. We hope that this Review will serve as a roadmap for advancing the scientific understanding of the fundamental factors governing electrochemical energy conversion in alkaline media with the ultimate goal of achieving ultralow Pt or precious-metal-free highperformance and durable alkaline fuel cells and related technologies.

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Section: Operando and In Situ Characterizationsmentioning

confidence: 99%

Section: Operando and In Situ Characterizationsmentioning

confidence: 99%

Section: Operando and In Situ Characterizationsmentioning

confidence: 99%

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Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

et al. 2022

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“…These difference spectra were obtained by subtracting the spectrum at 0.4 V vs RHE in panels a and b from the other spectra in the respective panels. This difference-based procedure highlights small spectral changes and can be used to identify adsorbates on Pt (electro)catalysts. ,− More specifically, the shape of a difference spectrum indicates the type of adsorbate, whereas the magnitude of a difference spectra indicates the relative abundances of these adsorbates . Including difference spectra in Figure therefore helps highlight subtle chemical changes in the Pt/C catalysts.…”

Section: Resultsmentioning

confidence: 99%

Base-Accelerated Degradation of Nanosized Platinum Electrocatalysts

et al. 2021

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In the pursuit of a hydrogen economy, extensive research has been directed at developing acidic and alkaline hydrogen fuel cells. Such fuel cells often utilize platinum-based catalysts. These materials have been studied extensively in acidic conditions but not in alkaline ones. This focus on acidic systems creates a marked knowledge gap, since recent studies indicate that carbon-supported platinum (Pt/C) electrocatalysts degrade more rapidly in bases than in acids. Addressing this gap, the present work investigates Pt/C degradation at pH 2 and pH 12 using electrochemistry, transmission electron microscopy (TEM), and in situ X-ray absorption spectroscopy (XAS). TEM and XAS reveal accelerated Pt/C degradation at high pH levels, which results in increased Ostwald ripening, Smoluchowski agglomeration, and nanoparticle detachment. These processes are driven by platinum-catalyzed carbon corrosion and the dissolution and redeposition of platinum nanoparticles. Although these processes take place at both low and high pH levels, basic conditions accelerate the degradation. Base-enhanced Pt dissolution and redeposition was assessed in further detail, revealing an oxidation onset reduction of 100 mV in the base; however, there were no significant differences between undissolved Pt oxidation in acid and in base. The results suggest that soluble Pt oxidation products are stabilized in the base instead. These conclusions are important for translating acidbased literature to alkaline conditions.

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“…One of the major obstacles in the commercial development of fuel cells is the sluggish oxygen reduction reaction (ORR) at the cathode. Platinum group metals (PGM) such as ruthenium, palladium, iridium and especially platinum (Pt) are the most current widely used active ORR catalysts, but have serious disadvantages like low methanol tolerance, scarcity (by weight Pt constitutes only 0.003 ppm in the Earth's crust and mere 172 tonnes of Pt were produced in 2016) and its high cost (24,000 United States Dollars (USD) per kg) prevents it to be a sustainable, economical and long-term electro-catalyst for ORR reaction [1]. Therefore, there have been intensive efforts by researchers to develop low-cost and durable non-PGM electro-catalysts.…”

Section: Introductionmentioning

confidence: 99%

Metal Organic Framework Derived MnO2-Carbon Nanotubes for Efficient Oxygen Reduction Reaction and Arsenic Removal from Contaminated Water

et al. 2020

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Even though manganese oxides are attractive materials for batteries, super-capacitors and electro-catalysts for oxygen reduction reactions, in most practical applications MnO2 needs to be hybridized with conductive carbon nano-structures to overcome its inherent poor electrical conductivity. In this manuscript we report microwave-assisted synthesis of MnO2 embedded carbon nanotubes (MnO2@CNT) from Mn-H3BTC (benzene-1,3,5-carboxylic acid) metal organic frameworks (MOF) precursors. Using graphene oxide as microwave susceptible surface, MnO2 nano-particles embedded in three dimensional reduced graphene oxide (rGO) -CNT frameworks (MnO2@CNT-rGO) were synthesized which when applied as electro-catalysts in oxygen reduction reaction (ORR) demonstrated comparable half-wave potential to commercial Pt/C, better stability, and excellent immunity to methanol crossover effect in alkaline media. When carbon fiber (CF) was used as substrate, three-dimensional MnO2@CNT-CF were obtained whose utility as effective adsorbents for arsenic removal from contaminated waters is demonstrated.

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Electrochemical Adsorption on Pt Nanoparticles in Alkaline Solution Observed Using In Situ High Energy Resolution X-ray Absorption Spectroscopy

Cited by 11 publications

References 34 publications

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Base-Accelerated Degradation of Nanosized Platinum Electrocatalysts

Metal Organic Framework Derived MnO2-Carbon Nanotubes for Efficient Oxygen Reduction Reaction and Arsenic Removal from Contaminated Water

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