Analysis of the oxidation state of platinum particles in supported catalysts by double differentiation of XPS lines

Smirnov, M. Yu.; Kalinkin, A. V.; Vovk, Evgeny I.; Bukhtiyarov, Valerii I.

doi:10.1134/s002247661606010x

Cited by 15 publications

(4 citation statements)

References 17 publications

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“…The spin–orbit coupling of Au 4f 7/2 and Au 4f 5/2 is 84 eV and 87.5 eV, indicating the presence of elemental Au 0 on the surface of the working electrode 11 , 12 . Also, Pt 4f 7/2 and Pt 4f 5/2 peaks were observed at 71.6 eV and 74.9 eV respectively 4 , 13 , 14 . On the other hand, upon using Ti mesh as the CE, no signal related to Ti was detected.…”

Section: Resultsmentioning

confidence: 92%

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

Hasan

Allam

2022

Sci Rep

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Electrochemical hydrogen evolution reaction (HER) is typically studied in three-electrode system. In this system, several counter electrodes are commonly used to ensure fast kinetics, including Pt, gold, and glassy carbon. However, the extensive application of such electrodes has raised caveats on the contribution of the redox-active species dissolving from such electrodes and redepositing on the surface of the working electrode to the measured overpotential. Consequently, this has been frequently confused with the actual electrochemical signature of the working electrode catalyst, resulting in a deceptive enhancement in the recorded overpotential. This issue becomes more critical when the electrolysis measurements involve an activation step, necessitating the need for alternative counter electrodes that are stable, especially in acidic medium, which is commonly used as the electrolyte in HER studies. Herein, while we systematically unveil such problems, an alternative counter electrode that overcomes those problems is demonstrated. Specifically, the correlation between the working electrode area to that of the counter electrode, the dissolution rate of the counter electrode, and the potential range used in the activation/cleaning of the surface on accelerating the dissolution rate is explored and discussed in detail. Finally, commercial Ti mesh is demonstrated as an alternative emerging counter electrode, which is proven to be very stable and convenient to study the HER in acidic media.

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Section: Resultsmentioning

confidence: 92%

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

Hasan

Allam

2022

Sci Rep

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“…At the initial stage of the interaction after exposures of 900 and 4500 L, the Pt 4f doublet shifts to higher BE, keeping the asymmetric shape of both spin–orbital components. In order to determine the possible number of states of platinum corresponding to the shape of the Pt 4f lines in the first three spectra, we used the method of double differentiation , of function describing the Pt 4f 7/2 line. Figure b gives the second derivatives of the function, describing the Pt 4f 7/2 line of the sample in the initial state and after its treatment in NO 2 at the exposures of 900 and 4500 L. For the fresh Pt/TiO 2 sample, the second derivative (Figure b, lowest curve) is characterized by one minimum, the position of which coincides with the position of the maximum of the Pt 4f 7/2 photoemission peak (Figure a, lowest spectrum).…”

Section: Resultsmentioning

confidence: 99%

XPS Study of Stability and Reactivity of Oxidized Pt Nanoparticles Supported on TiO₂

et al. 2017

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The method of X-ray photoelectron spectroscopy was used to study the interaction of the model Pt/TiO 2 catalysts with NO 2 and the following reduction of the oxidized Pt nanoparticles in vacuum, hydrogen, and methane. It was shown that, while interacting with NO 2 at room temperature, the metal Pt nanoparticles transform, first, into the phase which was tentatively assigned as particles containing subsurface/dissolved oxygen [Pt-O sub ], and then, into the PtO and PtO 2 oxides. If only the first state of platinum [Pt-O sub ] is formed, it demonstrates exclusively high reactivity toward hydrogen. For the samples containing simultaneously [Pt-O sub ], PtO, and PtO 2 , the highest reaction ability was demonstrated by PtO 2 ; contrary to the other two oxidized states, it is reducing while kept in vacuum under X-ray irradiation. All three coexisting states of the oxidized platinum can be reduced when heated in vacuum as well as while interacting with hydrogen at room temperature. First, PtO 2 is reduced to PtO. PtO and [Pt-O sub ] begin being reduced after the complete consumption of PtO 2 . We propose that, when a sample contains simultaneously all three states of oxidized platinum, the supported particles have a core− shell structure with a nucleus of perturbed platinum containing oxygen atoms, which are covered with a film of Pt oxides. It was shown that none of the oxidized states of platinum react with methane at room temperature.

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“…Before the laser treatment, the Pt 4f spectra have three peaks at 70.7, 73.2, and 75.8 eV (Figure S4F) assigned to Pt(0), Pt(II), and Pt(IV), respectively. , A very small fraction of Pt(0) is observed in agreement with the chemisorption capability of GO . After the laser treatment (Figure I), the synthesis of PtNPs was confirmed by a positive shift of the Pt 4f peaks to BEs of 71.4 eV (Pt 4f 7/2 ) and 74.5 eV (Pt 4f 5/2 ), with a spin–orbit splitting value of 3.1 eV, which is close to the metallic value (Δ = 3.4 eV). , Despite the fact that the Pt salt can form coordination complexes, the full reduction of the Pt precursor was confirmed by the Pt 4f 7/2 binding energy (71.4 eV) quite similar to the bulk platinum one (71.2 eV). , …”

Section: Resultsmentioning

confidence: 79%

“… 34 After the laser treatment ( Figure 3 I), the synthesis of PtNPs was confirmed by a positive shift of the Pt 4f peaks to BEs of 71.4 eV (Pt 4f 7/2 ) and 74.5 eV (Pt 4f 5/2 ), with a spin–orbit splitting value of 3.1 eV, which is close to the metallic value (Δ = 3.4 eV). 57 , 58 Despite the fact that the Pt salt can form coordination complexes, the full reduction of the Pt precursor was confirmed by the Pt 4f 7/2 binding energy (71.4 eV) quite similar to the bulk platinum one (71.2 eV). 23 , 59 …”

Section: Resultsmentioning

confidence: 98%

One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications

et al. 2023

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The combination of two-dimensional materials and metal nanoparticles (MNPs) allows the fabrication of novel nanocomposites with unique physical/chemical properties exploitable in high-performance smart devices and biosensing strategies. Current methods to obtain graphene-based films decorated with noble MNPs are cumbersome, poorly reproducible, and difficult to scale up. Herein, we propose a straightforward, versatile, surfactant-free, and single-step technique to produce reduced graphene oxide (rGO) conductive films integrating “naked” noble MNPs. This method relies on the instantaneous laser-induced co-reduction of graphene oxide and metal cations, resulting in highly exfoliated rGO nanosheets embedding gold, silver, and platinum NPs. The production procedure has been optimized, and the obtained nanomaterials are fully characterized; the hybrid nanosheets have been easily transferred onto lab-made screen-printed electrodes preserving their nanoarchitecture. The Au@rGO-, Ag@rGO-, and Pt@rGO-based electrodes have been challenged to detect caffeic acid, nitrite, and hydrogen peroxide in model solutions and real samples. The sensors yielded quantitative responses (R 2 ≥ 0.997) with sub-micromolar limits of detections (LODs ≤ 0.6 μM) for all the analytes, allowing accurate quantification in samples (recoveries ≥ 90%; RSD ≤ 14.8%, n = 3). This single-step protocol which requires low cost and minimal equipment will allow the fabrication of free-standing, MNP-embedded rGO films integrable into a variety of scalable smart devices and biosensors.

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Analysis of the oxidation state of platinum particles in supported catalysts by double differentiation of XPS lines

Cited by 15 publications

References 17 publications

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

XPS Study of Stability and Reactivity of Oxidized Pt Nanoparticles Supported on TiO₂

One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications

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Analysis of the oxidation state of platinum particles in supported catalysts by double differentiation of XPS lines

Cited by 15 publications

References 17 publications

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

An alternative, low-dissolution counter electrode to prevent deceptive enhancement of HER overpotential

XPS Study of Stability and Reactivity of Oxidized Pt Nanoparticles Supported on TiO2

One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications

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XPS Study of Stability and Reactivity of Oxidized Pt Nanoparticles Supported on TiO₂