Water Structure Controls Carbonic Acid Formation in Adsorbed Water

Aug 14, 2018 - ... structured H2O adsorbed as Ångstrom to nanometer thick layers on mineral surfaces are distinct from those facilitated by bulk liqu...
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Surfaces, Interfaces, and Catalysis; Physical Properties of Nanomaterials and Materials

Water Structure Controls Carbonic Acid Formation in Adsorbed Water Films Quin R.S. Miller, Eugene S. Ilton, Odeta Qafoku, David A Dixon, Monica Vasiliu, Christopher J. Thompson, Herbert Todd Schaef, Kevin M. Rosso, and John S. Loring J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.8b02162 • Publication Date (Web): 14 Aug 2018 Downloaded from http://pubs.acs.org on August 18, 2018

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Water Structure Controls Carbonic Acid Formation in Adsorbed Water Films Quin R. S. Miller*1, Eugene S. Ilton1, Odeta Qafoku1, David A. Dixon2, Monica Vasiliu2, Christopher J. Thompson1, Herbert T. Schaef1, Kevin M. Rosso1, and John S. Loring*1 1

Pacific Northwest National Laboratory, Richland, Washington 99352, United States

2

Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United

States AUTHOR INFORMATION Corresponding Authors *John S. Loring; [email protected] *Quin R. S. Miller; [email protected]

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ABSTRACT: Reaction pathways and kinetics in highly structured H2O adsorbed as Ångstroms to nanometers thick layers on mineral surfaces are distinct from those facilitated by bulk liquid water. We investigate the role of interfacial H2O structure in the reaction of H2O and CO2 to form carbonic acid (H2CO3) in thin H2O films condensed onto silica nanoparticles from humidified supercritical CO2. Rates of carbonic acid formation are correlated to spectroscopic signatures of H2O structure using oxygen isotopic tracers and infrared spectroscopy. While carbonic acid virtually does not form in the supercritical phase, the silica surface catalyzes this reaction by concentrating H2O through adsorption at hydrophilic silanol groups.

Within

measurement uncertainty, we found no evidence that carbonic acid forms when exclusively icelike structured H2O is detected at the silica surface. Instead, formation of H2C18O16O2 from H218O and C16O2 was found to be linearly correlated with liquid-like structured H2O that formed on the ice-like layer.

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The roles of water as both a reactant and a solvent can diverge dramatically from bulk liquid when confined as molecularly thin adsorbed H2O films. For example, acid-base reactions mediated by dust aerosol surfaces vary significantly with adsorbed H2O concentrations1-8, where even strong acids do not dissociate until a threshold concentration of adsorbed H2O is reached.1,9,10 Such effects can be related to the structure and limited conformational degrees of freedom of interfacial H2O, which differ from those of bulk water due to the influence of hydrophilic surface functional groups that disrupt an extended hydrogen bonding scheme.11-17 Substrate-imposed ordering of H2O significantly lowers its dielectric constant18-21 and diffusivity13,22-29 in interfacial H2O thin films compared to bulk water, broadly impacting sorption, hydration, dissociation, solvation, dissolution, precipitation, and electron transfer reactions. Thus, it is important to understand the relationships between H2O structure and interfacial reactivity at the molecular level. In this contribution we characterize the relationship between the structure of H2O in thin films and the formation of carbonic acid by reacting silica particles with variably humidified supercritical CO2.30,31 As detailed below, carbonic acid formation kinetics was tracked indirectly by measuring isotopic scrambling between H218O and C16O2. With respect to bulk water reactivity, electronic structure calculations have shown that the formation of carbonic acid in aqueous solution involves the active participation of at least three H2O molecules32,33, consistent with subsequent experimental work.34 There is also growing evidence that carbonic acid can form at mineral surfaces in the absence of bulk water, with implications for climate regulation, mineral weathering, CO2 sequestration, and elemental cycling.33,35-46 However, it remains unknown how rates of carbonic acid formation might correlate with the structure of interfacial H2O, which in turn depends on adsorbed H2O concentrations and nature of the mineral surface.

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As shown below, the silica surface promotes the formation of carbonic acid at relatively low H2O chemical potentials by concentrating H2O at hydrophilic silanol surface functional groups (≡Si-OH). Unlike previous studies involving Al- and Fe(III)-oxyhydroxides33,38-40 and divalent metal silicates41-46, we did not detect (bi)carbonate-metal surface complexes or precipitates after reaction with hydrated scCO2; hence, SiO2 serves to focus this study on the role of adsorbed H2O films in facilitating carbonic acid formation, and less on metal centers. Further, SiO2 is an important material in its own right due to its shear abundance and ubiquity in atmospheric dust, subsurface geologic formations, and building materials, as well as its use in catalyst supports.6,4749

Functional groups on SiO2 surfaces include hydrophobic siloxane bridges (Si-O-Si) and hydrophilic silanols (Si-OH).47,50-55 H2O adsorbs to silanol groups as surface-associated ice-like H2O with an infrared (IR) OH stretching band at ~3260 cm-1, and self-associated liquid-like H2O with an OH stretch at ~3420 cm-1.15,56-58 Theory suggests that H2O will more strongly interact with the surface OH sites than with another H2O molecule. The G3(MP2) value59 for the hydrogen bonding energy in (H2O)2 is 5.2, in excellent agreement with the complete basis set MP2 value60 of 5.0 kcal/mol (The corresponding G3(MP2) ∆H(0K) value is 3.0 kcal/mol). Our calculations revealed that the interaction of H2O with an H-O-SiX3 site ranges from ∆H(0K) = 4.7 kcal/mol for X = H to 6.1 kcal/mol for X = OH at the G3(MP2) level as shown in the Supporting Information. Thus, silanol-like OH groups could serve as nucleation sites for H2O cluster formation. Experiments used scCO2 stirred at 50 °C and 90 bar (directly relevant to deep geologic reservoirs41-46,61-65) and 15-20 nm amorphous nanoparticulate fumed silica (Sigma Aldrich S1530) with a surface area of 405±12 m2/g (Figure S1). As described below, the high density of

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O in scCO2 enabled the isotopic exchange methodology. The study was carried out in two

parts: First, IR spectra were collected of H2O adsorbed on SiO2 in order to determine normalized concentrations of ice-like and liquid-like H2O as a function of relative humidity (RH) and adsorbed H2O concentration. Then, in a separate set of experiments, isotopically labeled H218O was titrated into the dominant scC16O2 fluid. Transmission IR spectroscopy monitored the rate at which H218O was transformed into H216O as a function of RH and adsorbed H2O. Control experiments without SiO2 or with N2 instead of CO2 demonstrated that the isotopic exchange must have occurred during the formation of carbonic acid on the SiO2 substrate. Consequently, the rate of isotopic exchange served as reliable proxy for the rate of carbonic acid formation on the SiO2 surface. This data set allowed us to directly compare adsorbed H2O structure and carbonic acid formation rates. Although exchange of 18O has previously been used as an indirect method of probing the presence or possible absence of nanoscale adsorbed H2O films on carbonating minerals44,45,66, as well as a tracer to investigate adsorption and surface reactions of H2O and CO2 or O2 on oxide minerals, RH values were not systematically varied, nor were the kinetics of the 18

O exchange quantified.38-40,67,68 To the best of our knowledge this is the first experimental

study that quantifies the hydration kinetics of CO2 at a solid interface as a function of RH, adsorbed H2O concentration, and interfacial H2O structure. More specifically, high-pressure IR spectroscopic titrations (see Methods in SI for details) yielded molecular-level information at the SiO2 surface as a function of RH and adsorbed H2O concentration. Transmission IR (Figures S2 – S4) measured the scCO2 RH and concentration of adsorbed H2O. Attenuated total reflectance (ATR)-IR (Figure 1a,b) measured the spectrum of H2O adsorbed to SiO2 . With increasing RH and adsorbed H2O concentrations, the OH

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stretching bands of adsorbed H2O shifted to higher wavenumbers, indicating decreased hydrogen bonding in liquid-like, as opposed to more ordered ice-like H2O. Carbonic acid was not directly detected by ATR-IR, which is not surprising, given that its lifetime in bulk H2O before dissociation is only ~300 ns at 25 °C.34 We also did not detect dissolved (bi)carbonate or (bi)carbonate surface complexes, which is also not unexpected, considering that reported pHpzc values of SiO2 are typically less than 369,70, and that the pH of bulk water at experimental conditions is 2.9.71 At this low pH, surface groups will be predominately uncharged ≡Si-OH72, and our MP2/aug-cc-pVTZ/COSMO//B3LYP/DZVP2 correlated molecular orbital theory calculations in the Supporting Information show that the interaction of CO2 with Si(OH)4 to yield Si(OH)3OCO2H is unfavorable by 20.6 kcal/mol (∆Gaq(298)). ATR-IR spectra were processed with a multivariate curve resolution-alternating least squares (MCR-ALS) chemometrics analysis that uses a non-negativity constraint in both spectral and concentration space.73-75 As demonstrated by low residuals (Figure 1a,b), more than 99.97% of the variance in both experiments was explained by a simple model comprised of only two spectral components that are consistent with previously reported spectra of ice-like and liquidlike H2O (Figure 1c).15,56-58 The MCR-ALS calculated normalized concentrations of the two H2O structural modes are shown in Figure 1d. While a more complicated model that includes a third component slightly improves the fits, neither the resolved spectrum nor its associated normalized concentrations were reproduced between data sets.

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A .0015

EXP1

ATR-IR T = 50°C P = 90 bar 0.07268 g SiO2

C EXP1 Ice-like H2O

Measured Spectra Increasing RH

.0010

Absorbance

Absorbance

EXP2 Ice-like H2O

.0005

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0.0000

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Residuals from MCR-ALS Fit; R > 0.9999

3615

3415

3215

3015

2815

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ATR-IR T = 50°C P = 90 bar 0.10840 g SiO2

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Adsorbed H2O Concentration (µmol/m2)

Figure 1. Measured ATR-IR spectra (panels a and b) as a function of RH at an increment of ~5% from ~5% to ~85% RH from two IR titrations (EXP1 and EXP2) of SiO2 with H2O in scCO2 at 50 °C and 90 bar. Two-component MCR-ALS fits accounted for better than 99.97% of the variance, as demonstrated by the small residuals shown offset and below the measured spectra. The calculated spectral components are shown in panel c and are assigned to ice-like and liquidlike H2O, and the normalized concentrations of each of these components are shown in panel d as a function of adsorbed H2O concentration. We estimate an uncertainty in the predicted normalized concentrations of ±0.02 units (see error bar). The uncertainty in the adsorbed H2O concentration is ±0.2 µmol/m2, which is smaller than the diameter of the data symbols.

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The trends in ice-like and liquid-like H2O concentration (Figure 1) are generally consistent with previous work concerning H2O adsorption on silica.11,12,57,58,76 At the lowest H2O surface coverage attainable in our experiments, all of the adsorbed H2O was ice-like (Figure 1). Liquidlike H2O was first detected at ~1 µmol/m2 and increased with increasing adsorbed H2O; by ~4.5 µmol/m2 the interfacial H2O structure was predominantly liquid-like H2O. Ice-like H2O peaked at ~4 µmol/m2, and then decreased with increasing adsorbed H2O. This result is surprising because one might expect concentrations of ice-like H2O to plateau once all the hydrophilic silanol sites are occupied. Nonetheless, a similar trend was observed for a silica-film covered silicon ATR crystal modified with polyethylene glycol.76 A possible explanation is that initially ice-like H2O becomes more liquid-like as hydrogen bonds to other H2O molecules weaken interactions with surface silanol groups.77 Next, we measured rates of O isotope exchange between H2O and CO2 due to transient carbonic acid formation/dehydration in adsorbed H2O films on SiO2, as a function of RH and adsorbed H2O concentration. O exchange between H2O and CO2 is infrequent in scCO232,63,78,79, but readily occurs in the presence of a substrate.38-40,44 We used 18O enriched H2O (> 97 atom % purity), whereas scCO2 was overwhelmingly 16O. The scrambling of the 18O tracer proceeds by transport and adsorption of H218O and C16O2 to the silica surface, formation of carbonic acid (H2C18O16O2), likely reversible dissociation to HC18O16O2- and H+, the reformation of H216O and C16O18O two thirds of the time when H2C18O16O2 decomposes, and the desorption of H216O and C16O18O back into the scCO2 phase. Supporting experiments (see SI section) demonstrated that H2O adsorption, desorption, and transport through the stirred scCO2 fluid were at least an order of magnitude faster than O exchange. Once H2O is adsorbed to the surface, diffusion to CO2 will occur on the order of nanoseconds or less.23,24,29 Furthermore, carbonic acid dehydration and

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dissociation/association is 485 times faster (25 °C) than CO2 hydration in bulk water.34,80 Thus, the rate limiting step in our O exchange experiments is the formation of carbonic acid at the SiO2 surface. Individual isotope exchange experiments (see Methods in SI and Figure S5 for details) were conducted at 14 different adsorbed H2O concentrations at RH values between 5.8 and 76.8%. For each experiment, H218O hydrated scCO2 was injected into our high-pressure IR cell that contained SiO2; the same SiO2 sample was used on all experiments. O exchange was then tracked by collecting transmission IR spectra of H2O dissolved in stirred scCO2 as a function of time and exploiting the ~5 cm-1 isotopic shift in the HOH bending mode between H218O and H216O (see inset in Figure 2, as well as Figure S6). Spectra were analyzed using a MCR-ALS chemometrics analysis73-75 that quantified time-dependent normalized concentrations of H216O. The results were fit to an exponential growth function (see inset in Figure 2, as well as Figure S8-S9 for details) and initial O exchange rates (R0) were calculated and plotted in Figure 2 as a function of adsorbed H2O concentration. From ~0.5 µmol/m2 to ~1 µmol/m2, R0 values remained constant at slightly above background; above ~1 µmol/m2, R0 values increased with adsorbed H2O concentration. Additional experiments (see SI section, Figures S9 – S10) carried out in supercritical N2 showed that O exchange between H218O and 16O in SiO2 is insignificant, both in terms of rate and extent relative to exchange between H218O and 16O in scCO2.

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0 0

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Adsorbed H2O Concentration (µmol/m2) Figure 2. The initial rate of O exchange (R0) as a function of adsorbed H2O concentration on SiO2 for 14 in situ O isotope exchange experiments conducted at 50 °C and 90 bar. For each of these data points, there was a corresponding O exchange experiment in which transmission IR was used to monitor the HOH bend of dissolved H2O, converting from predominantly H218O at 1601 cm-1 to H216O at 1606 cm-1 (see top inset). The bottom inset shows the normalized concentration of H216O as a function of reaction time for the data point indicated by the green arrow. The green line denotes the fit to a three-parameter first order exponential growth function. Similar plots for the other 13 in situ O exchange experiments are shown in Figure S7. We estimate an uncertainty in R0 of ± 2 x 10-7 mmol·s-1·m-2 (see error bar). The uncertainty in the adsorbed H2O concentration is ±0.2 µmol/m2, which is smaller than the diameter of the data symbols.

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Comparison of Figure 1d to Figure 2 suggests that R0 might be better correlated to liquid-like H2O, rather than total H2O concentrations. To demonstrate this, we interpolated the H2O adsorption and structure results to calculate relative concentrations of liquid-like H2O at the corresponding adsorbed H2O concentrations of the O exchange experiments. In Figure 3, we plot R0 against these interpolated normalized concentrations, which clearly shows that carbonic acid formation is highly correlated with adsorbed H2O film structure (R2 > 0.99). This key result highlights the fundamental difference in reactivity between ice-like and liquid-like H2O at interfaces.

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6e-6 R2>0.993

5e-6 4e-6 3e-6 2e-6

Measured Data Linear Fit 95% Confidence Band

1e-6 0 0.0

.1

.2

.3

.4

.5

Normalized Concentration of Liquid-like H2O Figure 3. Strongly correlated (R2>0.993) linear relationship between initial rates of O exchange (R0) and normalized concentrations of liquid-like H2O on SiO2 at 50 °C and 90 bar.

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A simple physical model that can explain the linear correlation between R0 and liquid-like H2O involves H2O clustering. In this regard, spectroscopic77,81-83, calorimetric84, and molecular simulations85 indicate that H2O clusters form on SiO2 at neighboring hydrogen-bonded vicinal hydroxyls and geminal hydroxyls. The self-associated nature of H2O in these clusters is what yields the liquid-like spectrum that is manifest even at low chemical potentials of H2O. Mechanistically, it follows that carbonic acid formation at the SiO2 surface likely involves adsorbed liquid-like H2O clusters because several waters participate in the transition state to hydrate CO2, as noted above. Therefore, as the concentration of these clusters increases at the SiO2 surface, the rate of carbonic acid formation will increase. The maximum H2O coverage was ~8.5 µmol/m2 at 77% RH (85 ≤ RH ≤ 100% is not feasible due to condensation on IR viewports), but we speculate that R0 would continue to increase until the SiO2 surface is fully saturated with H2O clusters. Any further increase in adsorbed H2O might induce capillary condensation86 and a transition to a bulk-like water phase. At this point, our measured R0 values would increase sharply as rates of O exchange between CO2(g) and H2O(l) at 50 °C87 are approached, only to become limited by diffusion/transport, as shown previously for scCO2-H2O(l) O exchange at 34 °C and 79.6 bar.63 In summary, we have demonstrated an example where reactivity in adsorbed H2O films is intimately tied to H2O structure. Specifically, strongly surface-associated H2O adopting an icelike structure is not sufficiently free to solvate CO2 and form carbonic acid. Instead, carbonic acid formation rates are correlated to concentrations of H2O clusters having a liquid-like structure. Although we do not detect (bi)carbonate surface complexes, the possible mechanistic importance of coordination of CO2 at silanol functional groups is the subject of ongoing work using electronic structure calculations and molecular dynamics simulations. In fact, our current

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experiment study is consistent with a recent computational study showing that more H2O molecules in Al(OH)3-CO2-H2O clusters lowers activation barriers to carbonic acid formation.33

ASSOCIATED CONTENT Supporting Information. Figures S1-S10, electronic structure calculations, and experimental details, including SiO2 characterization, IR spectroscopic titration methods, O exchange experiments methods, chemometrics (MCR-ALS) analyses, and control experiments. This material is available free of charge on the ACS Publications website at DOI:

AUTHOR INFORMATION The authors declare no competing financial interests.

ACKNOWLEDGMENT This material is based upon work supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES), Chemical Sciences, Geosciences, and Biosciences Division through its Geosciences program at Pacific Northwest National Laboratory (PNNL). We appreciate the comments of two insightful reviewers, which led to substantial improvements to the clarity of this manuscript. We are also grateful to Sebastien N. Kerisit for constructive comments, as well as Paul F. Martin for help with apparatus design. DAD also thanks the Robert Ramsay Chair Fund of The University of Alabama for support.

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REFERENCES (1)

Fang, Y.; Tang, M. J.; Grassian, V. H. Competition between displacement and

dissociation of a strong acid compared to a weak acid adsorbed on silica particle surfaces: The role of adsorbed water, J. Phys. Chem. A 2016, 120, 4016-4024. (2)

Tang, M. J.; Larish, W. A.; Fang, Y.; Gankanda, A.; Grassian, V. H.

Heterogeneous reactions of acetic acid with oxide surfaces: Effects of mineralogy and relative humidity, J. Phys. Chem. A 2016, 120, 5609-5616. (3)

Cwiertny, D. M.; Young, M. A.; Grassian, V. H. Chemistry and photochemistry

of mineral dust aerosol, Annu. Rev. Phys. Chem. 2008, 59, 27-51. (4)

Prather, K. A.; Hatch, C. D.; Grassian, V. H. Analysis of atmospheric aerosols,

Annu. Rev. Anal. Chem. 2008, 1, 485-514. (5)

Tang, M. J.; Cziczo, D. J.; Grassian, V. H. Interactions of water with mineral dust

aerosol: Water adsorption, hygroscopicity, cloud condensation, and ice nucleation, Chem. Rev. 2016, 116, 4205-4259. (6)

Usher, C. R.; Michel, A. E.; Grassian, V. H. Reactions on mineral dust, Chemical

Reviews 2003, 103, 4883-4939. (7)

Donaldson, D. J.; Valsaraj, K. T. Adsorption and reaction of trace gas-phase

organic compounds on atmospheric water film surfaces: A critical review, Environ. Sci. Technol. 2010, 44, 865-873. (8)

Bianco, R.; Wang, S.; Hynes, J. T. Theoretical study of the dissociation of nitric

acid at a model aqueous surface, J. Phys. Chem. A 2007, 111, 11033-11042. (9)

Murdachaew, G.; Gaigeot, M. P.; Halonen, L.; Gerber, R. B. Dissociation of HCl

into ions on wet hydroxylated (0001) alpha-quartz, J. Phys. Chem. Lett. 2013, 4, 3500-3507.

ACS Paragon Plus Environment

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The Journal of Physical Chemistry Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(10)

Page 16 of 24

Devlin, J. P.; Uras, N.; Sadlej, J.; Buch, V. Discrete stages in the solvation and

ionization of hydrogen chloride adsorbed on ice particles, Nature 2002, 417, 269. (11)

Covert, P. A.; Jena, K. C.; Hore, D. K. Throwing salt into the mix: Altering

interfacial water structure by electrolyte addition, J. Phys. Chem. Lett. 2013, 5, 143-148. (12)

Dewan, S.; Yeganeh, M. S.; Borguet, E. Experimental correlation between

interfacial water structure and mineral reactivity, J. Phys. Chem. Lett. 2013, 4, 1977-1982. (13)

Argyris, D.; Tummala, N. R.; Striolo, A.; Cole, D. R. Molecular structure and

dynamics in thin water films at the silica and graphite surfaces, J. Phys.Chem. C 2008, 112, 13587-13599. (14)

Peters, S. J.; Ewing, G. E. Water on salt:  An infrared study of adsorbed H2O on

NaCl(100) under ambient conditions, J. Phys. Chem. B 1997, 101, 10880-10886. (15)

Ewing, G. E. Thin film water, J. Phys. Chem. B 2004, 108, 15953-15961.

(16)

Catalano, J. G.; Fenter, P.; Park, C. Water ordering and surface relaxations at the

hematite (110)–water interface, Geochim. Cosmochim. Acta 2009, 73, 2242-2251. (17)

Catalano, J. G. Relaxations and interfacial water ordering at the corundum (110)

surface, J. Phys.Chem. C 2010, 114, 6624-6630. (18)

Teschke, O.; Ceotto, G.; de Souza, E. F. Interfacial water dielectric-permittivity-

profile measurements using atomic force microscopy, Phys. Rev. E: Stat. Phys., Plasmas, Fluids, 2001, 64, 011605. (19)

McCafferty, E.; Pravdic, V.; Zettlemoyer, A. C. Dielectric behaviour of adsorbed

water films on the α-Fe2O3 surface, Trans. Faraday Soc. 1970, 66, 1720-1731. (20)

Senapati, S.; Chandra, A. Dielectric constant of water confined in a nanocavity, J.

Phys. Chem. B 2001, 105, 5106-5109.

ACS Paragon Plus Environment

16

Page 17 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry Letters

(21)

Fumagalli, L.; Esfandiar, A.; Fabregas, R.; Hu, S.; Ares, P.; Janardanan, A.;

Yang, Q.; Radha, B.; Taniguchi, T.; Watanabe, K.; Gomila, G.; Novoselov, K. S.; Geim, A. K. Anomalously low dielectric constant of confined water, Science 2018, 360, 1339-1342. (22)

Phan, A.; Ho, T. A.; Cole, D. R.; Striolo, A. Molecular structure and dynamics in

thin water films at metal oxide surfaces: Magnesium, aluminum, and silicon oxide surfaces, J. Phys.Chem. C 2012, 116, 15962-15973. (23)

Kerisit, S.; Bylaska, E. J.; Felmy, A. Water and carbon dioxide adsorption at

olivine surfaces, Chem. Geol. 2013, 359, 81-89. (24)

Kerisit, S.; Weare, J. H.; Felmy, A. R. Structure and dynamics of forsterite-

scCO2/H2O interfaces as a function of water content, Geochim. Cosmochim. Acta 2012, 84, 137151. (25)

Salles, F.; Douillard, J. M.; Bildstein, O.; El Ghazi, S.; Prelot, B.; Zajac, J.; Van

Damme, H. Diffusion of interlayer cations in swelling clays as a function of water content: Case of montmorillonites saturated with alkali cations, J. Phys.Chem. C 2015, 119, 10370-10378. (26)

Greathouse, J. A.; Cygan, R. T.; Fredrich, J. T.; Jerauld, G. R. Molecular

dynamics simulation of diffusion and electrical conductivity in montmorillonite interlayers, J. Phys.Chem. C 2016, 120, 1640-1649. (27)

Loganathan, N.; Yazaydin, A. O.; Bowers, G. M.; Kalinichev, A. G.; Kirkpatrick,

R. J. Cation and water structure, dynamics, and energetics in smectite clays: A molecular dynamics study of Ca-hectorite, J. Phys.Chem. C 2016, 120, 12429-12439. (28)

Tokunaga, T. K.; Finsterle, S.; Kim, Y.; Wan, J.; Lanzirotti, A.; Newville, M. Ion

diffusion within water films in unsaturated porous media, Environ. Sci. Technol. 2017, 51, 43384346.

ACS Paragon Plus Environment

17

The Journal of Physical Chemistry Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(29)

Page 18 of 24

Bourg, I. C.; Steefel, C. I. Molecular dynamics simulations of water structure and

diffusion in silica nanopores, J. Phys.Chem. C 2012, 116, 11556-11564. (30)

Spycher, N.; Pruess, K.; Ennis-King, J. CO2-H2O mixtures in the geological

sequestration of CO2. I. Assessment and calculation of mutual solubilities from 12 to 100°C and up to 600 bar, Geochim. Cosmochim. Acta 2003, 67, 3015-3031. (31)

Angus, S.; Armstrong, B.; De Reuck, K. IUPAC International Thermodynamic

Tables of the Fluid State: Carbon Dioxide; Pergamon Press: Oxford, 1976; Vol. 3. (32)

Nguyen, M. T.; Matus, M. H.; Jackson, V. E.; Ngan, V. T.; Rustad, J. R.; Dixon,

D. A. Mechanism of the hydration of carbon dioxide: Direct participation of H2O versus microsolvation, J. Phys. Chem. A 2008, 112, 10386-10398. (33)

Baltrusaitis, J.; Grassian, V. H. Carbonic acid formation from reaction of carbon

dioxide and water coordinated to Al(OH)3: A quantum chemical study, J. Phys. Chem. A 2010, 114, 2350-2356. (34)

Adamczyk, K.; Premont-Schwarz, M.; Pines, D.; Pines, E.; Nibbering, E. T. J.

Real-time observation of carbonic acid formation in aqueous solution, Science 2009, 326, 16901694. (35)

Butler, J. N. Carbon dioxide equilibria and their applications; CRC Press, 1991.

(36)

Stumm, W. Chemistry of the solid-water interface: processes at the mineral-water

and particle-water interface in natural systems; John Wiley & Son Inc., 1992. (37)

Berner, R. A. The long-term carbon cycle, fossil fuels and atmospheric

composition, Nature 2003, 426, 323. (38)

Baltrusaitis, J.; Grassian, V. H. Surface reactions of carbon dioxide at the

adsorbed water-iron oxide interface, J. Phys. Chem. B 2005, 109, 12227-12230.

ACS Paragon Plus Environment

18

Page 19 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry Letters

(39)

Baltrusaitis, J.; Jensen, J. H.; Grassian, V. H. FTIR Spectroscopy combined with

isotope labeling and quantum chemical calculations to investigate adsorbed bicarbonate formation following reaction of carbon dioxide with surface hydroxyl groups on Fe2O3 and Al2O3, J. Phys. Chem. B 2006, 110, 12005-12016. (40)

Baltrusaitis, J.; Schuttlefield, J. D.; Zeitler, E.; Jensen, J. H.; Grassian, V. H.

Surface reactions of carbon dioxide at the adsorbed water-oxide interface, J. Phys.Chem. C 2007, 111, 14870-14880. (41)

Loring, J. S.; Chen, J.; Benezeth, P.; Qafoku, O.; Ilton, E. S.; Washton, N. M.;

Thompson, C. J.; Martin, P. F.; McGrail, B. P.; Rosso, K. M.; Felmy, A. R.; Schaef, H. T. Evidence for carbonate surface complexation during forsterite carbonation in wet supercritical carbon dioxide, Langmuir 2015, 31, 7533-7543. (42)

Loring, J. S.; Miller, Q. R.; Thompson, C. J.; Schaef, H. T. In Science of Carbon

Storage in Deep Saline Formations: Process Coupling Across Time and Spatial Scales; Ilgen, A., Newell, P., Eds.; Elsevier: 2018. (43)

Loring, J. S.; Thompson, C. J.; Wang, Z.; Joly, A. G.; Sklarew, D. S.; Schaef, H.

T.; Ilton, E. S.; Rosso, K. M.; Felmy, A. R. In situ infrared spectroscopic study of forsterite carbonation in wet supercritical CO2, Environ. Sci. Technol. 2011, 45, 6204-6210. (44)

Miller, Q. R. S.; Thompson, C. J.; Loring, J. S.; Windisch, C. F.; Bowden, M. E.;

Hoyt, D. W.; Hu, J. Z.; Arey, B. W.; Rosso, K. M.; Schaef, H. T. Insights into silicate carbonation processes in water-bearing supercritical CO2 fluids, Int. J. Greenh Gas Control 2013, 15, 104-118.

ACS Paragon Plus Environment

19

The Journal of Physical Chemistry Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(45)

Page 20 of 24

Schaef, H. T.; McGrail, B. P.; Loring, J. L.; Bowden, M. E.; Arey, B. W.; Rosso,

K. M. Forsterite [Mg2SiO4] carbonation in wet supercritical CO2: An in situ high pressure X-ray diffraction study, Environ. Sci. Technol. 2013, 47, 174-181. (46)

Thompson, C. J.; Loring, J. S.; Rosso, K. M.; Wang, Z. M. Comparative reactivity

study of forsterite and antigorite in wet supercritical CO2 by in situ infrared spectroscopy, Int. J. Greenh Gas Control 2013, 18, 246-255. (47)

Bergna, H. E.; Roberts, W. O. Colloidal silica: fundamentals and applications;

CRC Press, 2005; Vol. 131. (48)

Rother, G.; Krukowski, E. G.; Wallacher, D.; Grimm, N.; Bodnar, R. J.; Cole, D.

R. Pore size effects on the sorption of supercritical CO2 in mesoporous CPG-10 silica, J. Phys.Chem. C 2012, 116, 917-922. (49)

Pettijohn, F. J.; Potter, P. E.; Siever, R. Sand and sandstone; Springer Science &

Business Media, 2012. (50)

Wang, R.; Wunder, S. L. Effects of silanol density, distribution, and hydration

state of fumed silica on the formation of self-assembled monolayers of noctadecyltrichlorosilane, Langmuir 2000, 16, 5008-5016. (51)

Zhuravlev, L. The surface chemistry of amorphous silica. Zhuravlev model,

Colloids Surf., A 2000, 173, 1-38. (52)

Milonjić, S. K. Determination of surface ionization and complexation constants at

colloidal silica/electrolyte interface, Colloids Surf. 1987, 23, 301-312. (53)

Zhuravlev, L.; Potapov, V. Density of silanol groups on the surface of silica

precipitated from a hydrothermal solution, Russ. J. Phys. Chem. A 2006, 80, 1119-1128.

ACS Paragon Plus Environment

20

Page 21 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry Letters

(54)

Laminack, W.; Gole, J. L.; White, M. G.; Ozdemir, S.; Ogden, A. G.; Martin, H.

J.; Fang, Z. T.; Wang, T. H.; Dixon, D. A. Synthesis of nanoscale silicon oxide oxidation state distributions: The transformation from hydrophilicity to hydrophobicity, Chem. Phys. Lett. 2016, 653, 137-143. (55)

Wang, T. H.; Gole, J. L.; White, M. G.; Watkins, C.; Street, S. C.; Fang, Z. T.;

Dixon, D. A. The surprising oxidation state of fumed silica and the nature of water binding to silicon oxides and hydroxides, Chem. Phys. Lett. 2011, 501, 159-165. (56)

Du, Q.; Freysz, E.; Shen, Y. R. Surface vibrational spectroscopic studies of

hydrogen bonding and hydrophobicity, Science 1994, 264, 826-828. (57)

Asay, D. B.; Barnette, A. L.; Kim, S. H. Effects of surface chemistry on structure

and thermodynamics of water layers at solid-vapor interfaces, J. Phys.Chem. C 2009, 113, 21282133. (58)

Asay, D. B.; Kim, S. H. Evolution of the adsorbed water layer structure on silicon

oxide at room temperature, J. Phys. Chem. B 2005, 109, 16760-16763. (59)

Curtiss, L. A.; Redfern, P. C.; Raghavachari, K.; Rassolov, V.; Pople, J. A.

Gaussian-3 theory using reduced Moller-Plesset order, J. Chem. Phys. 1999, 110, 4703-4709. (60)

Feyereisen, M. W.; Feller, D.; Dixon, D. A. Hydrogen bond energy of the water

dimer, J. Phys. Chem. 1996, 100, 2993-2997. (61)

Schaef, H. T.; Loganathan, N.; Bowers, G. M.; Kirkpatrick, R. J.; Yazaydin, A.

O.; Burton, S. D.; Hoyt, D. W.; Thanthiriwatte, K. S.; Dixon, D. A.; McGrail, B. P.; Rosso, K. M.; Ilton, E. S.; Loring, J. S. Tipping point for expansion of layered aluminosilicates in weakly polar solvents: Supercritical CO2, Acs Appl Mater Inter 2017, 9, 36783-36791.

ACS Paragon Plus Environment

21

The Journal of Physical Chemistry Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(62)

Page 22 of 24

McGrail, B. P.; Schaef, H. T.; Glezakou, V. A.; Dang, L. X.; Owen, A. T. Water

reactivity in the liquid and supercritical CO2 phase: Has half the story been neglected?, Energy Procedia 2009, 1, 3415-3419. (63)

Windisch, C. F. J.; Schaef, H. T.; Martin, P. F.; Owen, A. T.; McGrail, B. P.

Following 18O uptake in scCO2-H2O mixtures with Raman spectroscopy, Spectrochim. Acta, Part A 2012, 94, 186-191. (64)

Miller, Q. R. S.; Kaszuba, J. P.; Schaef, H. T.; Bowden, M. E.; McGrail, B. P.

Impacts of organic ligands on forsterite reactivity in supercritical CO2 fluids, Environ. Sci. Technol. 2015, 49, 4724-4734. (65)

Miller, Q. R. S.; Schaef, H. T.; Kaszuba, J. P.; Qiu, L.; Bowden, M. E.; McGrail,

B. P. Tunable manipulation of mineral carbonation kinetics in nanoscale water films via citrate additives, Environ. Sci. Technol. 2018, 52, 7138-7148. (66)

Schaef, H. T.; Windisch, C. F., Jr.; McGrail, B. P.; Martin, P. F.; Rosso, K. M.

Brucite [Mg(OH)2] carbonation in wet supercritical CO2: An in situ high pressure X-ray diffraction study, Geochimica et Cosmochimica Acta 2011, 75, 7458-7471. (67)

Henderson, M. A. Evidence for bicarbonate formation on vacuum annealed

TiO2(110) resulting from a precursor-mediated interaction between CO2 and H2O, Surf. Sci. 1998, 400, 203-219. (68)

Liao, L. F.; Lien, C. F.; Shieh, D. L.; Chen, M. T.; Lin, J. L. FTIR study of

adsorption and photoassisted oxygen isotopic exchange of carbon monoxide, carbon dioxide, carbonate, and formate on TiO2, J. Phys. Chem. B 2002, 106, 11240-11245. (69)

Davis, J. A.; Kent, D. In Reviews in Mineralogy and Geochemistry; Hochella, M.

F. J., White, A. F., Eds. 1990; Vol. 23, p 177-260.

ACS Paragon Plus Environment

22

Page 23 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry Letters

(70)

Parks, G. A. The isoelectric points of solid oxides, solid hydroxides, and aqueous

hydroxo complex systems, Chem. Rev. 1965, 65, 177-198. (71)

Toews, K. L.; Shroll, R. M.; Wai, C. M.; Smart, N. G. pH-defining equilibrium

between water and supercritical CO2. Influence on SFE of organics and metal chelates, Anal. Chem. 1995, 67, 4040-4043. (72)

Duval, Y.; Mielczarski, J. A.; Pokrovsky, O. S.; Mielczarski, E.; Ehrhardt, J. J.

Evidence of the existence of three types of species at the quartz-aqueous solution interface at pH 0-10: XPS surface group quantification and surface complexation modeling, J. Phys. Chem. B 2002, 106, 2937-2945. (73)

Gorzsás, A. MCR-ALS GUI V4c, Open source MATLAB script from the

Vibrational Spectroscopy Core Facility, Umeå University, Umeå Sweden, http://www.kbc.umu.se/english/visp/download-visp/, 10 Aug. 2018. (74)

de Juan, A.; Tauler, R. Multivariate curve resolution (MCR) from 2000: Progress

in concepts and applications, Crit. Rev. Anal. Chem. 2006, 36, 163-176. (75)

Yeşilbaş, M.; Boily, J.-F. Thin ice films at mineral surfaces, J. Phys. Chem. Lett.

2016, 7, 2849-2855. (76)

Anderson, A.; Ashurst, W. R. Interfacial water structure on a highly hydroxylated

silica film, Langmuir 2009, 25, 11549-11554. (77)

Klier, K.; Shen, J. H.; Zettlemo.Ac Water on silica and silicate surfaces. 1.

Partially hydrophobic silica, J. Phys. Chem. 1973, 77, 1458-1465. (78)

Rosenbaum, J. M. Gaseous, liquid, and supercritical fluid H2O and CO2: Oxygen

isotope fractionation behavior, Geochim. Cosmochim. Acta 1997, 61, 4993-5003.

ACS Paragon Plus Environment

23

The Journal of Physical Chemistry Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(79)

Page 24 of 24

Rosenbaum, J. M. Room-temperature oxygen-isotope exchange between liquid

CO2 and H2O, Geochim. Cosmochim. Acta 1993, 57, 3195-3198. (80)

Pocker, Y.; Bjorkquist, D. W. Stopped-flow studies of carbon-dioxide hydration

and bicarbonate dehydration in H2O and D2O - Acid-base and metal-ion catalysis, J. Am. Chem. Soc. 1977, 99, 6537-6543. (81)

Burneau, A.; Barres, O.; Gallas, J. P.; Lavalley, J. C. Comparative-study of the

surface hydroxyl-groups of fumed and precipitated silicas. 2. Characterization by infraredspectroscopy of the interactions with water, Langmuir 1990, 6, 1364-1372. (82)

Christy, A. A. New insights into the surface functionalities and adsorption

evolution of water molecules on silica gel surface: A study by second derivative near infrared spectroscopy, Vib. Spectrosc 2010, 54, 42-49. (83)

Takeuchi, M.; Bertinetti, L.; Martra, G.; Coluccia, S.; Anpo, M. States of H2O

adsorbed on oxides: An investigation by near and mid infrared spectroscopy, Appl. Catal., A 2006, 307, 13-20. (84)

Wu, D.; Guo, X. F.; Sun, H.; Navrotsky, A. Energy landscape of water and

ethanol on silica surfaces, J. Phys.Chem. C 2015, 119, 15428-15433. (85)

Ma, Y. C.; Foster, A. S.; Nieminen, R. M. Reactions and clustering of water with

silica surface, J. Chem. Phys. 2005, 122. (86)

Heath, J. E.; Bryan, C. R.; Matteo, E. N.; Dewers, T. A.; Wang, Y.; Sallaberry, C.

J. Adsorption and capillary condensation in porous media as a function of the chemical potential of water in carbon dioxide, Water Resour. Res. 2014, 50, 2718-2731. (87)

Leuenberger, M.; Huber, C. On-line determination of oxygen isotope ratios of

water or ice by mass spectrometry, Anal. Chem. 2002, 74, 4611-4617.

ACS Paragon Plus Environment

24