The pH-Dependent Surface Charging and the Points of Zero Charge

Kosmulski, Marek

doi:10.1006/jcis.2002.8490

Cited by 808 publications

(183 citation statements)

References 10 publications

(7 reference statements)

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“…The maximum noise PSD level appears pH~5, which is close to the point of zero charge of SiN x . 46 Since the bulk current is kept constant and so is its noise component, the observed pH related variations of noise PSD can only be attributed to the change in surface charge density, thereby confirming the contribution of surface current to flicker noise. As a final proof, the flicker noise of smallerdiameter pores shows a stronger pH dependence when the noise PSD is compared for nanopores of different sizes (see Supporting Information Figure S8), since larger effects of surface current are expected for smaller-diameter pores.…”

Section: Origin Of the Nanopore Flicker Noisementioning

confidence: 80%

Generalized Noise Study of Solid-State Nanopores at Low Frequencies

et al. 2017

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Nanopore technology has been extensively investigated for analysis of biomolecules, and a success story in this field concerns DNA sequencing using a nanopore chip featuring an array of hundreds of biological nanopores (BioNs). Solid-state nanopores (SSNs) have been explored to attain longer lifetime and higher integration density than what BioNs can offer, but SSNs are generally considered to generate higher noise whose origin remains to be confirmed. Here, we systematically study low-frequency (including thermal and flicker) noise characteristics of SSNs measuring 7 to 200 nm in diameter drilled through a 20-nm-thick SiN x membrane by focused ion milling. Both bulk and surface ionic currents in the nanopore are found to contribute to the flicker noise, with their respective contributions determined by salt concentration and pH in electrolytes as well as bias conditions. Increasing salt concentration at constant pH and voltage bias leads to increase in the bulk ionic current and noise therefrom. Changing pH at constant salt concentration and current bias results in variation of surface charge density, and hence alteration of surface ionic current and noise. In addition, the noise from Ag/AgCl electrodes can become predominant when the pore size is large and/or the salt concentration is high. Analysis of our comprehensive experimental results leads to the establishment of a generalized nanopore noise model. The model not only gives an excellent account of the experimental observations, but can also be used for evaluation of various noise components in much smaller nanopores currently not experimentally available.

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Section: Origin Of the Nanopore Flicker Noisementioning

confidence: 80%

Generalized Noise Study of Solid-State Nanopores at Low Frequencies

et al. 2017

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“…Gaboriaud and Ehrhardt [27] thought this hysteresis effect originates from carbonate contamination. And Kosmulski [40] attributed the behavior to the disparity of fast reaction and slow pH drift. By making a comparison with the blank electrolyte titration data, we can exclude the …”

Section: Resultsmentioning

confidence: 99%

Surface acid–base properties and hydration/dehydration mechanisms of aluminum (hydr)oxides

Yang

Sun

Wang

et al. 2007

Journal of Colloid and Interface Science

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“…closer to the reported value of pH 8-10. 13,[24][25][26] In a recent study by Kershner et al, 16 it was shown that crystalline alumina powder with relatively uniform shapes (Sumitomo AA-2) has p.z.c. at pH 3.8, while random-shaped alumina powder They found that -Al 2 O 3 platelets with mainly (0001) surfaces had a p.z.c.…”

Section: Discussionmentioning

confidence: 99%

Structures and Charging of α-Alumina (0001)/Water Interfaces Studied by Sum-Frequency Vibrational Spectroscopy

et al. 2008

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Sum-frequency vibrational spectroscopy in the OH stretch region was employed to study structures of water/ -Al 2 O 3 (0001) interfaces at different pH values. Observed spectra indicate that protonation and deprotonation of the alumina surface dominate at low and high pH, respectively, with the interface positively and negatively charged accordingly. The point of zero charge (p.z.c.) appears at pH ~6.3, which is close to the values obtained from streaming potential and second harmonic generation studies. It is significantly lower than the p.z.c. of alumina powder. The result can be understood from the pK values of protonation and deprotonation at the water/ -Al 2 O 3

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The pH-Dependent Surface Charging and the Points of Zero Charge

Cited by 808 publications

References 10 publications

Generalized Noise Study of Solid-State Nanopores at Low Frequencies

Generalized Noise Study of Solid-State Nanopores at Low Frequencies

Surface acid–base properties and hydration/dehydration mechanisms of aluminum (hydr)oxides

Structures and Charging of α-Alumina (0001)/Water Interfaces Studied by Sum-Frequency Vibrational Spectroscopy

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