Second harmonic generation studies of anionic chemisorption at polycrystalline platinum electrodes

Campbell, Deborah J.; Lynch, Matthew L.; Corn, Robert M.

doi:10.1021/la00101a006

Cited by 26 publications

(23 citation statements)

References 2 publications

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“…These results agree well with those derived from SHG (D.L.) 34 and electrochemical (O upd ) 20,38 measurements, and demonstrate a quantitative approach that works for the entire potential window, with better sensitivity and accuracy for the characterizations of low concentration analyte in a much smaller sample volume.…”

Section: ■ Experimental Apparatussupporting

confidence: 83%

“…Due to their abundance in natural and industrial environments, a mechanistic study of the halide adsorption (especially in trace amounts) on Pt catalysts is of both fundamental and practical significance. Historically, due to the lack of intrinsic infrared spectroscopic features, in situ studies of halide adsorption on Pt surface relied heavily on X-ray based spectroscopy ,− and nonlinear optical method of SHG. , For these approaches, sensitivity is a general challenge. X-ray based technologies have relied on synchrotron source for increased signals, often implemented with ultrathin electrochemical cells for reduced beam attenuation, and the studies were only performed at relatively high chloride concentrations (10 –3 M). ,− ,− …”

Section: Resultsmentioning

confidence: 99%

“…The qualitatively similar yet quantitatively stronger ETS signals from Br ads are consistent with a stronger binding of Br ads to Pt surface compared with Cl ads . For Pt–I ads , it is commonly known that an irreversibly adsorbed zerovalent iodine monolayer is formed on the Pt surface upon exposure to iodide anions, , which remains stable over a wide potential range and strongly inhibits the hydrogen and oxygen adsorption on the Pt surface. This unique I ads characteristic results in a “flat” ETS and dETS curves, with only slight hydrogen and oxygen adsorption features at high overpotentials (Figure e,f).…”

Section: Resultsmentioning

confidence: 99%

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On-Chip in Situ Monitoring of Competitive Interfacial Anionic Chemisorption as a Descriptor for Oxygen Reduction Kinetics

et al. 2018

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The development of future sustainable energy technologies relies critically on our understanding of electrocatalytic reactions occurring at the electrode–electrolyte interfaces, and the identification of key reaction promoters and inhibitors. Here we present a systematic in situ nanoelectronic measurement of anionic surface adsorptions (sulfates, halides, and cyanides) on ultrathin platinum nanowires during active electrochemical processes, probing their competitive adsorption behavior with oxygenated species and correlating them to the electrokinetics of the oxygen reduction reaction (ORR). The competitive anionic adsorption features obtained from our studies provide fundamental insight into the surface poisoning of Pt-catalyzed ORR kinetics by various anionic species. Particularly, the unique nanoelectronic approach enables highly sensitive characterization of anionic adsorption and opens an efficient pathway to address the practical poisoning issue (at trace level contaminations) from a fundamental perspective. Through the identified nanoelectronic indicators, we further demonstrate that rationally designed competitive anionic adsorption may provide improved poisoning resistance, leading to performance (activity and lifetime) enhancement of energy conversion devices.

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Section: ■ Experimental Apparatussupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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On-Chip in Situ Monitoring of Competitive Interfacial Anionic Chemisorption as a Descriptor for Oxygen Reduction Kinetics

et al. 2018

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“…This increase is similarly also observed by the same group on polycrystalline platinum electrodes. 21,22 They also report a rotational anisotropy of the second harmonic ͑SH͒ signal for ps and sp polarization in accordance with the expected C 3v symmetry of this surface. Interestingly, the CO-covered Pt͑111͒ electrode featured an additional isotropic contribution for ps polarization at variance with the C 3v symmetry.…”

Section: Introductionmentioning

confidence: 84%

“…This potential dependence of the SH signal during the negative-going scan is also observed in all subsequent cycles. The same response was already reported by Lynch et al 23,22 and is assigned to the clean Pt͑111͒ surface in HClO 4 solution.…”

Section: Methodsmentioning

confidence: 99%

Potential-dependence of CO adlayer structures on Pt(111) electrodes in acid solution: Evidence for a site selective charge transfer

Akemann¹,

Friedrich²,

Stimming³

2000

The Journal of Chemical Physics

100

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Simultaneous in situ monitoring of surface and gas species and surface properties by modulation excitation polarization-modulation infrared reflection-absorption spectroscopy: CO oxidation over Pt filmThe oxidation of carbon monoxide on a Pt͑111͒ electrode surface is studied under transient and stationary reaction conditions in a 0.1 M HClO 4 aqueous solution as a function of the applied electrode potential. The optical response is investigated by optical second harmonic generation ͑SHG͒ at 280 nm and infrared absorption spectroscopy ͑IRAS͒ starting at low potentials where the electrode is not reactive ͓e.g., 0.1 V vs the reversible hydrogen electrode ͑RHE͔͒ towards more positive potentials where CO oxidation is initiated. For transient reaction conditions, in the absence of CO dissolved in solution, the oxidation starts at about 0.5 V vs. RHE and consists of a fast oxidation of about 10% of the adlayer and of a second reaction with slower kinetics involving the removal of the complete CO layer ͑overlayer stripping͒. Under steady-state conditions in CO-saturated solution the CO adlayer is stable up to 0.9 V vs RHE. At 0.63 V an overlayer phase transition is indicated by a 20% increase of the isotropic component of the second harmonic ͑SH͒ intensity ͑pp-polarization͒. The same potential region for this phase transition in the adlayer structure is derived from IRAS spectra after correcting for the effect of the thin layer electrolyte in IRAS measurements. The disappearance of hollow sites, the appearance of bridge sites, as well as an increased occupation of on-top sites at 0.63 V is interpreted as corresponding to the adlayer phase transition. The observations are consistent with a transition from the c(2ϫ2) to the (ͱ19ϫͱ19) adlayer structure of CO. The high sensitivity of SHG with regard to structural phase transitions of the CO adlayer is explained by distinct charge transfer contributions to the second-order surface susceptibility at different coordination sites.

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2 Surface Thermodynamics of Metal/Solution Interface: the Untapped Resources

Tsirlina

2011

Modern Aspects of Electrochemistry

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Second harmonic generation studies of anionic chemisorption at polycrystalline platinum electrodes

Cited by 26 publications

References 2 publications

On-Chip in Situ Monitoring of Competitive Interfacial Anionic Chemisorption as a Descriptor for Oxygen Reduction Kinetics

On-Chip in Situ Monitoring of Competitive Interfacial Anionic Chemisorption as a Descriptor for Oxygen Reduction Kinetics

Potential-dependence of CO adlayer structures on Pt(111) electrodes in acid solution: Evidence for a site selective charge transfer

2 Surface Thermodynamics of Metal/Solution Interface: the Untapped Resources

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