Water Oxidation Catalysis for NiOOH by a Metropolis Monte Carlo

Subscriber access provided by UNIV OF NEW ENGLAND ARMIDALE

Quantum Electronic Structure

Water Oxidation Catalysis for NiOOH by a Metropolis Monte Carlo Algorithm Chen Hareli, and Maytal Caspary Toroker J. Chem. Theory Comput., Just Accepted Manuscript • DOI: 10.1021/acs.jctc.7b01214 • Publication Date (Web): 03 Apr 2018 Downloaded from http://pubs.acs.org on April 17, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 13 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

Journal of Chemical Theory and Computation

Water Oxidation Catalysis for NiOOH by a Metropolis Monte Carlo Algorithm Chen Hareli and Maytal Caspary Toroker* Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel Keywords: DFT, Algorithm Metropolis, nickel oxyhydroxide, catalysis, OER.

Abstract Understanding catalytic mechanisms is important for discovering better catalysts, particularly for water splitting reactions that are of great interest to the renewable energy field. One of the best performing catalysts for water oxidation is nickel oxyhydroxide (NiOOH). However, only one mechanism has been adopted so far for ̅ 5). In order to understand how a modeling catalysis of the active plane: 𝛽 − 𝑁𝑖𝑂𝑂𝐻(01 second reaction mechanism affects catalysis, we perform Density Functional Theory +U (DFT+U) calculations of a second mechanism for water oxidation reaction of NiOOH. Then we use a Metropolis Monte Carlo algorithm to calculate how many catalytic cycles are completed when two reaction mechanisms are competing. We find that within the Metropolis algorithm, the second mechanism has a higher overpotential and is therefore not active even for large applied biases.

*Corresponding author: E-mail: [email protected] , Tel.: +972 4 8294298.

ACS Paragon Plus Environment

Journal of Chemical Theory and Computation 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

1. Introduction Understanding the mechanism of heterogeneous chemical reactions on surfaces is fundamental for developing new catalysts. The intimate details of the bonding between intermediate species and the surface can reveal the role of the surface composition in catalyzing the reaction. 1-2 One of the most studied reactions in recent years is the water oxidation reaction since the number of inexpensive and efficient catalysts are scarce.3 One of the best catalysts for water oxidation at alkaline conditions is nickel oxyhydroxide (NiOOH). Therefore, NiOOH has been utilized in many sophisticated architectures of electrochemical devices. 4-6 In recent years, the success of NiOOH intrigued scientists to unravel the source of its superior performance. 7-11 However, many fundamental questions still remain. 11 ̅ 5), Only a single catalytic mechanism has been proposed for 𝛽 − 𝑁𝑖𝑂𝑂𝐻(01 which may be one of the active phases of NiOOH and is one of the most extensively studied phases of NiOOH.9, 11 The mechanism includes four deprotonation steps: 9 A + h+  B + H+ B + h+ + H2O  C + H+ C + h+  D + H+ D + h+ + H2O  A + H+ +O2 where intermediate "A" is the surface with a monolayer of adsorbed water molecules and intermediate "B" is the surface with one of the water molecules cleaved to form an adsorbed hydroxyl group. Intermediates "C" and "D" are similar to "A" and "B", respectively, but the former have an additional penetrating oxygen atom in the surface that forms and O-O bond. The more commonly used reaction mechanism that has been proposed for several metal oxides includes these reaction steps: 12 A + h+  B + H+ B + h+  E + H+ E + h+ + H2O  F + H+ F + h+  G + H+ + O2 G + H2O  A Here intermediate "E" has a *O termination after a second deprotonation reaction, intermediate "F" has *OOH termination, and "G" has a * vacant termination. In this


Page 2 of 13

Page 3 of 13 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


reaction mechanism water is adsorbed on a vacant site and an O-O bond is formed after a second water molecule is adsorbed at the active site. In this paper, we use a unique combination of Density Functional Theory +U (DFT+U) and a Metropolis algorithm to model water oxidation on NiOOH. The novel aspects of this study are: 1. This is the first DFT study that models water oxidation according to the most common mechanism proposed for oxides, but that have never been studied for NiOOH. This is the second reaction mechanism from above that we denote as the "ABEFG" reaction, according to the names of the participating intermediates. 2. This is the first Monte Carlo algorithm used for NiOOH. We use a Metropolis algorithm to test how the second mechanism pathway effects catalysis. We find that the second mechanism requires a larger overpotential and is therefore less effective. Some surprising findings include: 1. The second mechanism does not proceed even at high biases. 2. There is a probability that the reaction will proceed even below the overpotential. This statistical effect may contribute to the deviation between calculated overpotentials that have been presented in the literature and the voltage at which the current begins to rise.

2. Methods and Calculation Details The Vienna Ab-initio Simulation Package (VASP) program was used to perform spin-polarized DFT calculations.13-14 The Perdew-Burke-Ernzerhof (PBE)15 functional with the DFT+U formalism of Duradev et al.16 was chosen with a U-J term of 5.5 eV and 3.3 eV for Ni and Fe, respectively, as usually for modeling catalysis of doped NiOOH.9, 17-20 This choice of functional predicts well the electronic structure and activity of NiOOH as extensively reported in previous studies.9-10, 20 Projectedaugmented wave (PAW) potentials replaced the core electrons of Ni 1s2s2p3s3p, Fe 1s2s2p3s3p , and O 1s.21-22 ̅ 5) facet and the dopant The unit cell of β-NiOOH9, 23-26 was cleaved at the (01 was located at the active site as done in previous literature.8-9 We considered several possible reaction intermediates as shown in Figure 1. The energy cutoff of 600 eV and k-point Gamma-centered grid of 2x2x1 were converged to within 0 where 𝑃𝑖→𝑗 is the probability to move forward in the reaction from intermediate "i" to "j" and ∆𝐺𝑖→𝑗 is the free energy of an intermediate reaction step from intermediate "i" to "j". In practice, a random number R between zero and one is chosen if the free energy is positive, and if the number falls above the thermal weight 𝑒 −∆𝐺𝑖 →𝑗 /𝑘𝐵 𝑇 then 𝑃𝑖→𝑗 = 1 (otherwise, if the number falls below 𝑒 −∆𝐺𝑖→𝑗 /𝑘𝐵 𝑇 then 𝑃𝑖→𝑗 = 0). Another way to write the criterion in terms of the random number R is: 𝑃𝑖→𝑗 = 1 𝑖𝑓 ∆𝐺𝑖→𝑗 ≤ 0 𝑃𝑖→𝑗 = 1 𝑖𝑓 ∆𝐺𝑖→𝑗 > 0 and 𝑅 < 𝑒 −∆𝐺𝑖→𝑗 /𝑘𝐵 𝑇 𝑃𝑖→𝑗 = 0 𝑖𝑓 ∆𝐺𝑖→𝑗 > 0 and 𝑅 > 𝑒 −∆𝐺𝑖 →𝑗 /𝑘𝐵 𝑇 We generalized the algorithm to consider two reaction pathways. All codes are provided as supporting information.

3. Results In this section, we present free energy calculations of the water oxidation reaction for pure and Fe-doped for both "ABCD" and "ABEFG" reaction mechanisms. First, we compare the free energies for water oxidation of the two mechanisms. Then we show that by using a Metropolis Monte Carlo algorithm on pure and Fe-doped NiOOH then the second reaction is not active even at high potentials. Our central result is that the free energy required for the less studied ABEFG reaction mechanism is larger than the ABCD reaction for water oxidation for both pure and Fe-doped NiOOH (see Figure 2a and 2b for the two reactions, respectively). For the pure case, the F intermediate was found unstable, that is the calculation did not converge the geometry of intermediate F and therefore the reaction ABEG without intermediate F is considered. The corresponding free energy of reaction ABEG is the highest (1.13 eV in Table 1). Both the instability of one intermediate and the high overpotential indicate that this reaction in unfavorable for pure NiOOH. For the Fedoped case, all intermediates were found stable, but the overpotential is still higher than the ABCD reaction (0.76 eV vs. 0.33 eV for Fe-doped NiOOH in Table 1). Table 1. Free energies and overpotentials for pure and Fe-doped NiOOH for two reaction pathways without pH and voltage correction terms. The highest free energies are indicated in bold. Units are in eV. Reaction ABCD

Pure NiOOH

A to B B to C C to D D to A

1.75 1.03 1.41 0.27

Fe-doped NiOOH 1.44 1.43 1.19 0.39

Overpotential

0.64

0.33

Reaction ABEG A to B B to E E to G G to A


Pure NiOOH 1.75 2.24 0.31 0.16 1.13

Reaction ABEFG A to B B to E E to F F to G G to A

Fe-doped NiOOH 1.44 1.87 1.10 -0.11 0.16 0.76


Figure 2a. The ABCD reaction mechanisms of the water oxidation reaction for Fedoped NiOOH.

Figure 2b. The ABEFG reaction mechanisms of the water oxidation reaction for Fedoped NiOOH. In agreement with previous experiment,7 the overpotential decreases upon Fedoping for both mechanisms. For reactions ABCD and ABEFG, the overpotential


Page 6 of 13

Page 7 of 13 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


decreases by ~0.3-0.4 eV due to the addition of Fe-doping. Hence, Fe-doping reduces the overpotential regardless of the mechanism chosen. The highest free energy required for each reaction is different, related to the fact that these are different mechanisms with different reaction steps. For the ABCD reaction, the first deprotonation is most demanding and for the ABEFG reaction then the second deprotonation requires the most energy. This can be visualized through the cumulative free energies in Figure 3, where the largest rise appears at different stages of the reactions. As a result, intermediate "B" is likely to proceed to intermediate "C" and not to intermediate "E".

Figure 3. Cumulative free energies of water oxidation reaction for pure NiOOH in two reaction mechanisms. In order to account for how much catalytic cycles can be completed when both reactions are competing, then we generalized the Metropolis Algorithm for two reaction mechanisms. At a given constant voltage and pH, many steps are made in order to progress through the reaction from intermediate to intermediate. Starting from intermediate A, and in each of the following steps, the algorithm checks if the free energy to move forward is negative (or zero) or positive. The reaction moves forward to the next reaction intermediates if the free energy is negative (or zero) or if a random number is smaller than the Boltzmann distribution to move forward. However, if the reaction is at intermediate B then the reaction could progress to either intermediate C or E. The criterion for choosing reaction ABCD over reaction ABEFG is based on statistical Boltzmann probabilities: 𝑒 −∆𝐺𝐵→𝐶/𝑘𝐵𝑇

𝑃 = 𝑒 −∆𝐺𝐵→𝐸/𝑘𝐵𝑇 +𝑒−∆𝐺𝐵→𝐶/𝑘𝐵𝑇. In practice, a random number is chosen between zero and one and the criterion includes the following conditions: 𝑃𝐵→𝐶 = 1 𝑖𝑓 ∆𝐺𝐵→𝐶 > 0 and ∆𝐺𝐵→𝐸 > 0 and 𝑅 < 𝑃 𝑃𝐵→𝐸 = 1 𝑖𝑓 ∆𝐺𝐵→𝐶 > 0 and ∆𝐺𝐵→𝐸 > 0 and 𝑅 > 𝑃 𝑃𝐵→𝐶 = 1 𝑖𝑓 ∆𝐺𝐵→𝐶 > 0 and ∆𝐺𝐵→𝐸 > 0 and 𝑅 < 𝑒 −∆𝐺𝐵→𝐶 /𝑘𝐵 𝑇 and 𝑅 > 𝑒 −∆𝐺𝐵→𝐸/𝑘𝐵 𝑇 𝑃𝐵→𝐶 𝑜𝑟 𝐸 = 0 𝑖𝑓 ∆𝐺𝐵→𝐶 > 0 and ∆𝐺𝐵→𝐸 > 0 and 𝑅 > 𝑒 −∆𝐺𝐵→𝐶 /𝑘𝐵 𝑇 and 𝑅 > 𝑒 −∆𝐺𝐵→𝐸/𝑘𝐵 𝑇 𝑃𝐵→𝐶 = 1 𝑖𝑓 ∆𝐺𝐵→𝐶 ≤ 0 and ∆𝐺𝐵→𝐸 ≤ 0 and 𝑅 < 𝑃



𝑃𝐵→𝐸 = 1 𝑖𝑓 ∆𝐺𝐵→𝐶 ≤ 0 and ∆𝐺𝐵→𝐸 ≤ 0 and 𝑅 > 𝑃 𝑃𝐵→𝐶 = 1 𝑖𝑓 ∆𝐺𝐵→𝐶 < 0 and ∆𝐺𝐵→𝐸 > 0 The value of P is always 1.0 (favors transition to C) since 𝑒 −∆𝐺𝐵→𝐶 /𝑘𝐵 𝑇 ≫ 𝑒 −∆𝐺𝐵→𝐸/𝑘𝐵 𝑇 for our calculated free energies at room temperature. Hence, the reaction will proceed with the ABCD mechanism in all cases, even for high voltages. As can be seen in Figure 4a, the reactivity is dominated by the ABCD mechanism and never has a contribution from the ABEFG mechanism.

Figure 4a. Percentage of reaction cycles completed (divided by the number of reaction steps) vs. applied voltage. "ABCD rate" and "ABEFG rate" show the contribution of each mechanism to the total reaction of Fe-doped NiOOH. In order to better understand the possible contribution of the second reaction mechanism, we set the value of P=0.5. Under this condition, for low voltages the reaction can proceed in through the ABCD mechanism. But at high enough voltages then the reaction proceeds in both paths and the reaction efficiency reduces since the ABEFG path requires more reaction steps (see Figure 4b). Since generally the efficiency is expected to increase with voltage, then the probability P cannot be equal to 0.5 for this model. The efficiency of the reaction at high voltages will depend on the relative kinetics of the two mechanisms and goes beyond the Metropolis algorithm.29

Figure 4b. Percentage of reaction cycles completed (divided by the number of reaction steps) vs. applied voltage for equal probability P=1 to proceed in each mechanism. "ABCD rate" and "ABEFG rate" show the contribution of each mechanism to the total reaction of Fe-doped NiOOH.


Page 8 of 13

Page 9 of 13 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


In the Metropolis algorithm, the reaction proceeds based on a statistical weight that depends on voltage and temperature for a given set of intermediate reaction free energies. As can be seen in Figure 5, the reaction proceeds through intermediates ABCD every cycle for voltage E=0.5 eV. At this voltage, some trials do not allow transition to states "B" or "C" since some of the free energies are still positive: ∆𝐺𝐴→𝐵 = 0.11, ∆𝐺𝐵→𝐶 = 0.10, ∆𝐺𝐶→𝐷 = −0.22, and ∆𝐺𝐷→𝐴 = −0.94 𝑒𝑉. However, there is still some probability for completing the reaction and therefore there is a rise in reactants completed even below the overpotential required for all reactions to have negative free energies.

Figure 5. Showing individual steps in the range of 15000 ≤ 𝑀𝑜𝑛𝑡𝑒 𝐶𝑎𝑟𝑙𝑜 𝑆𝑎𝑚𝑝𝑙𝑒 ≤ 16000 at a constant voltage E=0.5 Volts for Fe-doped NiOOH. An interesting consequence of the Metropolis model is that the reactivity doesn't abruptly increase at the value where the voltage equals the overpotential (then the free energies of all intermediate reactions of the ABCD path are negative). Even below the overpotential, there is a Boltzmann probability that the reaction will proceed. The slope of the increase in reactivity is more moderate at higher temperatures (see Figure 6). This statistical effect may contribute to the deviation between calculated overpotentials and the voltage at which the current begins to rise. For example, the OER of hematite rises at 0.5-0.6 V, while the calculated overpotential is 0.7 V. 30-31

Figure 6. Reactivity dependence on temperature for Fe-doped NiOOH.



4. Conclusions The effect of two possible reaction mechanisms operating simultaniously has been investigated using a combined DFT+U and Metropolis Monte Carlo algorithm. The DFT+U free energies were calculated for water oxidation with pure and Fe-doped NiOOH. Then, a set of two energetic pathways for water oxidation catalysis were considered in a Monte Carlo algorithm at different applied biases and temperatures. The DFT+U calculations reveal that the second mechanism "ABEFG" has a higher overpotential. As a result, the reaction is likely to proceed through the first mechanism "ABCD". For the first "ABCD" reaction, the first deprotonation is most demanding and for the second "ABEFG" reaction then the second deprotonation requires the most energy. In any one of the two mechanisms, Fe-doping reduces the overpotential, in agreement with experiment. 7 This study focuses on consequences arising from using the Metropolis thermodynamic algorithm without taking account kinetic effects that need to be incorporated in the future through, for example, a kinetic Monte Carlo Algorithm. 29 However, several interesting observation can be made through the thermodyna mic condition set forth: 1. The reaction has preference for the thermodynamical favorable mechanism when more than one mechanism is considered. 2. The efficiency can rise even below the thermodynamic threshold at high temperatures. The latter statistical effect may contribute to the early rise of current in experiments.

Acknowledgements This research was supported by the Nancy and Stephen Grand Technion Energy Program, the I-CORE Program of the Planning and Budgeting Committee, The Israel Science Foundation (Grant No. 152/11), and a grant from the Ministry of Science and Technology (MOST), Israel. This work was supported by the post LinkSCEEM-2 project, funded by the European Commission under the 7th Framework Programme through Capacities Research Infrastructure, INFRA-2010-1.2.3 Virtual Research Communities, Combination of Collaborative Project and Coordination and Support Actions (CP-CSA) under grant agreement no RI-261600.

Supporting information available Further details on zero point energy calculations and codes for the Metropolis Monte Carlo algorithm are provided in the supporting information.

References 1. Dieterich, J. M.; Carter, E. A., Opinion: Quantum Solutions for a Sustainable Energy Future. 2017, 1, 0032. 2. Muñoz-García, A. B.; Carter, E. A., Non-Innocent Dissociation of H2o on Gap(110): Implications for Electrochemical Reduction of Co2. Journal of the American Chemical Society 2012, 134, 13600-13603. 3. Sivula, K.; van de Krol, R., Semiconducting Materials for Photoelectrochemical Energy Conversion. 2016, 16010.


Page 10 of 13

Page 11 of 13 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


4. Görlin, M.; Ferreira de Araújo, J.; Schmies, H.; Bernsmeier, D.; Dresp, S.; Gliech, M.; Jusys, Z.; Chernev, P.; Kraehnert, R.; Dau, H., et al., Tracking Catalyst Redox States and Reaction Dynamics in Ni–Fe Oxyhydroxide Oxygen Evolution Reaction Electrocatalysts: The Role of Catalyst Support and Electrolyte Ph. Journal of the American Chemical Society 2017, 139, 2070-2082. 5. Malara, F.; Minguzzi, A.; Marelli, M.; Morandi, S.; Psaro, R.; Dal Santo, V.; Naldoni, A., Α-Fe2O3/NiOOH: An Effective Heterostructure for Photoelectrochemical Water Oxidation. ACS Catalysis 2015, 5, 5292-5300. 6. Landman, A.; Dotan, H.; Shter, G. E.; Wullenkord, M.; Houaijia, A.; Maljusch, A.; Grader, G. S.; Rothschild, A., Photoelectrochemical Water Splitting in Separate Oxygen and Hydrogen Cells. Nat Mater 2017, 16, 646-651. 7. Trotochaud, L.; Young, S. L.; Ranney, J. K.; Boettcher, S. W., Nickel–Iron Oxyhydroxide Oxygen-Evolution Electrocatalysts: The Role of Intentional and Incidental Iron Incorporation. Journal of the American Chemical Society 2014, 136, 6744-6753. 8. Friebel, D.; Louie, M. W.; Bajdich, M ;.Sanwald, K. E.; Cai, Y.; Wise, A. M.; Cheng, M.-J.; Sokaras, D.; Weng, T.-C.; Alonso-Mori, R., et al., Identification of Highly Active Fe Sites in (Ni,Fe)Ooh for Electrocatalytic Water Splitting. Journal of the American Chemical Society 2015, 137, 1305-13.13 9. Li, Y.-F.; Selloni, A., Mechanism and Activity of Water Oxidation on Selected Surfaces of Pure and Fe-Doped NiOx. ACS Catalysis 2014, 4, 1148-1153. 10. Tkalych, A. J.; Yu, K.; Carter, E. A., Structural and Electronic Features of Β-Ni(OH)2 and Β-NiOOH from First Principles. The Journal of Physical Chemistry C 2015, 119, 2431524322. 11. Fidelsky, V.; Toroker, M. C., The Secret Behind the Success of Doping Nickel Oxyhydroxide with Iron. Physical Chemistry Chemical Physics 2017, 19, 7491-7497. 12. Man ,I. C.; Su, H.-Y.; Calle-Vallejo, F.; Hansen, H. A.; Martínez, J. I.; Inoglu, N. G.; Kitchin, J.; Jaramillo, T. F.; Nørskov, J. K.; Rossmeisl, J., Universality in Oxygen Evolution Electrocatalysis on Oxide Surfaces. ChemCatChem 2011, 3, 1159-1165. 13. Kresse, G.; Hafner, J., \Textit{Ab Initio} Molecular Dynamics for Liquid Metals. Phys. Rev. B 1993, 47, 558-561. 14. Kresse, G.; Furthmüller, J., Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Comp. Mater. Sci. 1996, 6, 15-50. 15. Perdew, J. P.; Burke, K.; Ernzerhof, M., Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865-3868. 16. Dudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P., Electron-Energy-Loss Spectra and the Structural Stability of Nickel Oxide:$\Hskip0.3em${}$\Hskip0.3em${}an Lsda+U Study. Phys. Rev. B 1998, 57, 15051509. 17. Li, Y.-F.; Selloni, A., Mosaic Texture and Double C-Axis Periodicity of Β-NiOOH: Insights from First-Principles and Genetic Algorithm Calculations. J. Phys. Chem. Lett. 2014, 5, 3981-3985. 18. Tkalych, A. J.; Yu, K.; Carter, E. A., Structural and Electronic Features of BetaNi(OH)2 and Beta-NiOOH from First Principles. J. Phys. Chem. C 2015, 119, 24315-24.322 19. Fidelsky, V.; Caspary Toroker, M., Engineering Band Edge Positions of Nickel Oxyhydroxide through Facet Selection. The Journal of Physical Chemistry C 2016, 120, 81048108. 20. Zaffran, J.; Caspary Toroker, M., Benchmarking Density Functional Theory Based Methods to Model NiOOH Material Properties: Hubbard and Van Der Waals Corrections Vs Hybrid Functionals. Journal of Chemical Theory and Computation 2016, 12, 3807-3812. 21. Blöchl, P. E., Projector Augmented-Wave Method. Physical Review B 1994 ,50 , .17953-17979 22. Kresse, G.; Joubert, D., From Ultrasoft Pseudopotentials to the Projector Augmented Wave Method. Physical Review B 1999, 59, 1758-1775.



23. Casas-Cabanas, M.; Canales-Vázquez, J.; Rodríguez-Carvajal, J.; Palacín, M. R., Deciphering the Structural Transformations During Nickel Oxyhydroxide Electrode Operation. Journal of the American Chemical Society 2007, 129, 5840-5842. 24. Oliva, P.; Leonardi, J.; Laurent, J. F.; Delmas, C.; Braconnier, J. J.; Figlarz, M.; Fievet, F.; Guibert, A. d ,.J. Power Sources 1982, 8, 229-255. 25. Delaplane, R. G.; Ibers, J. A.; Ferraro, J. R.; Rush, J. J., Diffraction and Spectroscopic Studies of the Cobaltic Acid System HCoC2–DCoO2. The Journal of Chemical Physics 1969, 50, 1920-1927. 26. Chen, J.; Selloni ,A., First Principles Study of Cobalt (Hydr)Oxides under Electrochemical Conditions. The Journal of Physical Chemistry C 2013, 117, 20002-20006. 27. Momma, K.; Izumi, F., Vesta 3 for Three-Dimensional Visualization of Crystal, Volumetric and Morphology Data. Journal of Applied Crystallography 2011, 44, 1272-1276. 28. Bajdich, M.; García-Mota, M.; Vojvodic, A.; Nørskov, J. K.; Bell, A. T., Theoretical Investigation of the Activity of Cobalt Oxides for the Electrochemical Oxidation of Water. Journal of the American Chemical Society 2013, 135, 13521-13530. 29. Dybeck, E. C.; Plaisance, C. P.; Neurock, M., Generalized Temporal Acceleration Scheme for Kinetic Monte Carlo Simulations of Surface Catalytic Processes by Scaling the Rates of Fast Reactions. Journal of Chemical Theory and Computation 2017, 13, 1525-1538. 30. Liao, P.; Keith, J. A.; Carter, E. A., Water Oxidation on Pure and Doped Hematite (0001) Surfaces: Prediction of Co and Ni as Effective Dopants for Electrocatalysis. Journal of the American Chemical Society 2012, 134, 13296-13309. 31. Sivula, K.; Le Formal, F.; Grätzel, M., Solar Water Splitting: Progress Using Hematite (Α-Fe2O3) Photoelectrodes. ChemSusChem 2011, 4, 432-449.


Page 12 of 13

Page 13 of 13 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


Table of Contents Graphic 177x101mm (300 x 300 DPI)


Water Oxidation Catalysis for NiOOH by a Metropolis Monte Carlo

Recommend Documents