bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromium-Rich Core-Shell Cr
x
Ir1-X
O2 Nanotubes for Highly Efficient Oxygen Evolution Reaction in Alkaline Solution
Authors: Jin Dasol , Kang Jisoo , Lee Youngmi , Kim Myung Hwa , Jin Dasol 
Published: July 2022

Considering the growing attention to oxygen evolution reaction (OER) as a key role in clean energy through electrocatalytic water splitting, advanced materials for water oxidation are central to the area of renewable energy. In general, the OER process, involved four electron and four proton coupled electrochemical reaction, demands higher kinetics to overcome an overpotential than HER (hydrogen evolution reaction). For this aspect, significant research efforts have been devoted to developing efficient OER electrocatalyst with enhanced electrocatalytic kinetics and long-term durability.
Here we present the synthetic processes and physical/electrochemical characterization of Cr
x
Ir1-x
O2 nanotubes (NTs). Those NTs are synthesized through electrospinning, a simple way to facilitate 1D nanostructure, and post-thermal annealing process with different annealing speed (°C /min). As-prepared Cr
x
Ir1-x
O2 NTs at the optimized conditions have shown outstanding OER electrocatalytic activity in alkaline media from the viewpoints of overpotential and Tafel slope as well as durability. The morphology and compositions of Cr
x
Ir1-x
O2 were characterized by a field emission scanning electron microscope (FESEM) equipped with an energy dispersive X-ray spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The crystalline structures of the prepared Cr
x
Ir1-x
O2 are investigated through high-resolution X-ray diffraction (XRD). Electrochemical activities for oxygen evolution reaction (OER) are studied with rotating disk electrode (RDE) voltammetry in N2-saturated 1.0 M KOH (aq); and compared with those of iridium single component oxides (IrOx and IrO2) and commercial iridium (cIr, counterparts in OER electrocatalysts).
This work was financially supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT or by the Ministry of Education (NRF-2019R1F1A1059969, NRF-2018R1A6A1A03025340, NRF-2020R1A2B5B01001984, and NRF-2019R1F1A1062799).
Surface Reconstruction of Iridium Nanoparticles for Enhanced Oxygen Evolution Reaction in Alkaline Medium
Authors: Kim Myeong-Geun , Yoo Sung Jong 
Published: July 2022

An electrochemical water splitting is a promising technology that can generate green hydrogen using renewable energy sources. However, the sluggish oxygen evolution reaction (OER) in an anodic side hinders their large scale applications. Many efforts have been focused on developing efficient electrocatalysts; iridium-based catalysts have gained much attentions due to remarkable intrinsic activities and high stability. Technically, however, the properties are derived from amorphous iridium oxide (IrOx) rather than metallic Ir. During an electrochemical activation process, the Ir metal is easily converted into oxidized species with multiple oxidation states of iridium, which are highly active toward OER. Similarly, many catalysts undergo changes during OER process (e.g., oxidation of precatalysts), resulting in enhancement of activities for OER beyond corresponding original catalysts. Accordingly, the reconstruction process involving surface oxidation and leaching of metal cations should be investigated to develop efficient OER electrocatalysts.
Herein, we prepared chalcogen atom modified Ir/IrOx core/shell nanoparticles for enhanced alkaline OER performances (electrolyte: 1M KOH). The S-modified Ir/IrOx exhibited remarkable OER performances with current density of 10 mA cm−2 at overpotentials as low as 180 mV. Incorporation of chalcogen atoms induce surface reconstruction of the Ir/IrOx nanoparticles during OER measurements. It was observed that electrocatalytic activities of Ir/IrOx were varied depending on the type and concentration of chalcogen atoms. There were no observable morphological and structural changes in Ir/IrOx electrocatalyst, whereas the atomic ratio of chalcogen atoms noticeably decreased after OER tests. The result suggests that incorporated chalcogen atoms play a role in modifying the surface of Ir nanoparticles, rather than participating OER as active sites. In addition, XPS measurements were conducted in order to detect changes in chemical states of the catalysts during electrochemical process. We thus believe that the chalcogen atom induced surface reconstruction can be the strategy to efficiently improve the various electrochemical reactions.
(Digital Presentation) Tuning Oxygen Reduction on Monoclinic and Tetragonal Zirconia Surfaces Using Oxygen Vacancy and Nitrogen Doping: A Density-Functional Study
Authors: Muhammady Shibghatullah , Haruyama Jun , Kasamatsu Shusuke , Sugino Osamu 
Published: July 2022

The proton exchange membrane fuel cell (PEMFC) shows the interesting properties,1 where oxygen reduction reaction (ORR) is rate-determining.2 For the PEMFC, Pt-based materials are effective to be its ORR catalyst but their expensive cost and the limited availability are unavoidable,3 motivating to searching non-Pt materials. Zirconia (ZrO2) becomes a considerable candidate for the ORR catalyst since it has a higher chemical stability than that of Pt in an acidic environment,4 where tetragonal ZrO2 (t-ZrO2) (101) and monoclinic ZrO2 (m-ZrO2) (-111) surfaces have been observed to be the most stable.5

In this study, oxygen reduction reaction (ORR) on m-ZrO2 (-111), (-101), (110) and t-ZrO2 (101) surfaces is investigated using the density-functional theory. Each surface is divided into two regimes, that are pristine and defective surfaces, containing defects as two nitrogen impurities and an oxygen vacancy (2NO + VO). Then, the effect of the defects on free energy diagrams and bonding characteristics of an adsorbed oxygen (O*) is investigated. The free energy diagrams correspond to elementary ORR steps involving four intermediates, that are O2*, O2H*, O*, and OH*.
As the results, the free energy diagrams show that the first electron transfer, corresponding to the formation of O2H*, is rate-determining on the pristine surfaces. It is modified to the third and fourth electron transfers, corresponding to the formation and removal of OH*, on the defective t-ZrO2 and m-ZrO2 surfaces, respectively. Furthermore, the defects provide a significant effect on the bonding of O*, leading to a slight improvement of ORR catalytic activity on t-ZrO2 but an apparent decrease on m-ZrO2 surfaces. Moreover, due to the defects, adsorption free energies for the defective m-ZrO2 surfaces, ΔG
O, ΔG
OH, and ΔG
OOH, are moving away from the universal scaling curve and the ideal catalyst point. On the other hand, for the defective t-ZrO2 surface, ΔG
O, ΔG
OH, and ΔG
OOH are off the universal scaling curve, heading to the ideal catalyst point. Our result presents the significant effect of the defects, providing a new insight into the oxide-based catalysts.

References

E. Brightman et al., J. of Power Sources, 242, 244–254 (2013)

M. Beltrán-Gastélum et al., Energy, 181, 1225–1234 (2019)

X. Sun et al., Electrochim. Acta, 332, 135474 (2020)

A. Ishihara et al., J. Phys. Chem. C, 123(30), 18150–18159 (2019)

C. Morterra et al., Mater. Chem. Phys., 37(3), 243–257 (1994)
(Digital Presentation) Evaluating Stability and Performance of Nasicon Membranes for Crossover Mitigation in Aqueous Redox-Flow Batteries
Authors: Modak Sanat Vibhas , Valle Joseph , Kwabi David G. , Sakamoto Jeff 
Published: July 2022

Most polymer-based membranes that are used in prototypical aqueous redox-flow batteries (RFBs) do not adequately prevent crossover of small-molecule reactants, causing high rates of capacity fade. Ceramic superionic conductor membranes are an attractive alternative due to their superior abilities to mitigate crossover;1 they can thus enable the deployment of electrolytes containing earth-abundant, small-molecule reactants.2
3 We test the performance and stability of a von Alpen sodium superionic conductor Na3.1Zr1.55Si2.3P0.7O11 (NaSICON) as an RFB membrane by examining its resistance, permeability and interfacial morphology as a function of electrolyte composition and temperature. The resistance of NaSICON is stable for several weeks while immersed in neutral to strongly alkaline ([OH-] = 3 M) aqueous electrolytes, and its permeability to polysulfide-based and permanganate-based small-molecule RFB reactants is negligible compared to that of Nafion. The glassy phase of the NaSICON microstructure at the membrane-electrolyte interface undergoes small amounts of etching while in contact with aqueous electrolytes containing sodium ions, which becomes more extensive when potassium ions are present in the electrolyte, leading in certain instances to complete disintegration of the membrane. We report a ferrocyanide-permanganate flow cell at a pH of 14.5 with a ~ 700 μm-thin NaSICON membrane supporting weeks of cycling with apparently negligible reactant crossover and very low capacity fade (< 0.04 %/day). Area-specific resistance of NaSICON falls dramatically with increasing temperature and decreasing membrane thickness, and a membrane that is 100 µm thick or thinner can enable power densities at above-ambient temperatures that are comparable to power densities of polymer membrane-containing flow cells.
(1) Yu, X.; Gross, M. M.; Wang, S.; Manthiram, A. Aqueous Electrochemical Energy Storage with a Mediator-Ion Solid Electrolyte. Advanced Energy Materials
2017, 7 (11), 1602454, https://doi.org/10.1002/aenm.201602454. DOI: https://doi.org/10.1002/aenm.201602454 (acccessed 2021/03/12).
(2) Wei, X.; Xia, G.-G.; Kirby, B.; Thomsen, E.; Li, B.; Nie, Z.; Graff, G. G.; Liu, J.; Sprenkle, V.; Wang, W. An aqueous redox flow battery based on neutral alkali metal ferri/ferrocyanide and polysulfide electrolytes. J. Electrochem. Soc.
2016, 163 (1), A5150-A5153. DOI: 10.1149/2.0221601jes].
(3) Colli, A. N.; Peljo, P.; Girault, H. H. High energy density MnO4-/MnO42- redox couple for alkaline redox flow batteries. Chem Commun (Camb)
2016. DOI: 10.1039/c6cc08070g.
Triarylamines: Promising Candidates As Aqueous Organic Redox Flow Catholytes
Authors: Farag Nadia L , Jethwa Rajesh , Beardmore Alice E , Grey Clare P. , Wright Dominic S. 
Published: July 2022

Redox flow batteries (RFBs) have significant potential in grid-level electrical energy storage, generated by renewable sources such as wind or solar power. Of particular interest in this research are aqueous organic electrolyte systems due to their safety, cost, fast kinetics and greater sustainability compared to the use of conventional inorganic electrolytes or organic solvents. To date this area has been limited by both the solubility and long term cycling stability of organic electrolytes.1 The most difficult challenge in this field is the development of stable organic catholytes that have high redox potentials, high energy density, and high battery efficiency. Triarylamines (TAAs) have the potential to meet these criteria because of the ease of functional group modification allowing for variation of the redox potential, and the low reorganisation energy between the neutral and radical states.2,3

TAAs have previously been explored as catholyte materials in organic non-aqueous RFBs, with studies showing that the redox properties of these easily prepared compounds can be tuned by judicious choice of functional groups at the para positions.4 It was also shown that TAAs have high cycling stability compared to other popular catholytes such as TEMPOL.5 However, TAAs have not previously been used as catholytes in aqueous RFBs.
In this work, a number of TAAs were explored with various substituents in the para-positions of their aromatic rings, with the aim of promoting good aqueous solubility and cycling stability (two of the main selection criteria for any RFB electrolyte). Tris-4-amino-phenyl amine was found to be the most promising candidate, with reversible redox at high positive potentials, ease of synthesis, and reasonable aqueous solubility. Extensive electrochemical investigations using cyclic voltammetry (CV), impedance and full cell cycling were carried out which provide clues as to how the TAA framework can be modified to improve the redox properties for future catholyte applications.
Figure 1: Triarylamine framework containing various substituents and CV of 1mM Tris-4-amino-phenyl amine with a scan rate of 20 mV/s in 1 M HCl with a Ag/AgCl reference electrode, glassy carbon working electrode and platinum counter electrode
1 R. M. Darling, K. G. Gallagher, J. A. Kowalski, S. Ha and F. R. Brushett, Energy Environ. Sci., 2014, 7, 3459–3477.
2 Tohru Nishinaga, Organic Redox Systems, Synthesis, Properties and Applications, Wiley, 2016.
3 J. Wang, K. Liu, L. Ma and X. Zhan, Chem. Rev., 2016, 116, 14675–14725.
4 I. A. V. Romadina, Elena I., K. J. Stevensona and P. A. Troshin, Mater. Chem. A, 2021, 9, 8303–8307.
5 G. Kwon, K. Lee, J. Yoo, S. Lee, J. Kim, Y. Kim, J. E. Kwon, S. Y. Park and K. Kang, Energy Storage Mater., 2021, 42, 185–192.

Figure 1
(Invited) Electrochemical Reduction of Carbon Dioxide to Oxygenates and Hydrocarbons
Authors: Yeo Boon Siang Jason 
Published: July 2022

Currently, more than 80% of the world’s energy needs are met by burning fossil fuels. Supplies of these fuels are intrinsically limited and will eventually run out. Combustion of fossil fuels also generates carbon dioxide, whose rapidly increasing atmospheric concentration contributes to global warming. One solution for mitigating atmospheric concentrations of CO2 is to electrochemically reduce these molecules into chemicals and fuels. If the energy used for these processes is generated from renewable sources such as solar and wind, we can envisage a chemical production cycle that is closed-loop with net zero carbon emission.
In this talk, we share our recent works related to the development of catalysts for the selective electroreduction of CO2 to oxygenates and hydrocarbons. We shall show the pathway by which CO2 could be converted to 1-butanol, a C4 alcohol. Through a series of control experiments and density functional theory (DFT) calculations, we pinpoint that its C4 backbone was formed from a surface-mediated aldol condensation of acetaldehyde formed from CO2 reduction, rather through the coupling of four CO intermediates. We also discuss how CO2 could be reduced to methanol through a tandem process - CO2 was first reduced to formic acid, and the latter can be reduced to methanol using anodized titanium. For the latter step, experiments and DFT calculations identify Ti3+ and oxygen vacancies (TOV) as the active sites in a vacancy-filling pathway mediated by *H2COOH. We also give screening rules based on the *HCOOH and *H2COOH binding energies alongside TOV formation energies. These can facilitate the high-throughput automated design of catalysts for CH3OH synthesis from tandem CO2 electrolysis. In the last part of our talk, we show how molecules not commonly observed during CO2 reduction such as propylene and other C4-C6 products could be formed.

References:

- W.J. Teh, O. Pique, Q.H. Low, W.H. Zhu, F. Calle-Vallejo and B.S. Yeo. Toward Efficient Tandem Electroreduction of CO2 to Methanol using Anodized Titanium. ACS Catal. 11, 8467. 2021.
- L.R.L. Ting, Y.J. Peng, B.S. Yeo. Mechanistic Insights into the Selective Electroreduction of Crotonaldehyde to Crotyl Alcohol and 1-Butanol. ChemSusChem. 14, 2963. 2021.
- L.R.L. Ting, R. García-Muelas, A.J.M. Martín, F.L.P. Veenstra, S.T.J. Chen, Y. Peng, E.Y.X. Per, S. Pablo-García, N. López, J. Pérez-Ramírez, and B.S. Yeo. Electrochemical Reduction of Carbon Dioxide to 1-Butanol on Oxide-Derived Copper. Angew. Chemie Int. Ed. 59, 21072. 2020.
(Invited) Effect of Nanostructure and Surface Chemistry on Activity and Selectivity of Cu-Based Electrocatalysts for Carbon Dioxide Reduction
Authors: He Yanghua , Zelenay Piotr 
Published: July 2022

Electrochemical conversion of carbon dioxide (CO2) to value-added chemicals using electricity from renewable sources represents a promising path to carbon-neutral fuel cycle and enhanced economic benefits.1 To date, copper (Cu) has been the leading metal electrocatalyst for the electroreduction of CO2 to high-value chemicals: fuels and chemical feedstocks. Although there has been a significant progress in CO2 reduction reaction (CO2RR), the overall CO2RR performance of Cu-based electrocatalysts is still limited by poor selectivity, resulting in a variety of products, such as hydrogen, carbon monoxide, formic acid, methane, and ethylene.2 Enhancing the CO2RR rate relative to the competing hydrogen evolution reaction (HER) and achieving high selectivity for multi-carbon products thus represent the major scientific challenges.
In this presentation, we will summarize our study of innovative Cu-based catalysts aimed at producing high energy-density chemicals, enhancing the understanding of reaction mechanism, and bringing CO2RR closer to practical application. The study has focused on the relationship between the composition and structure of Cu-based electrocatalysts, especially the nanostructure and oxidation states (Cu0, Cu+, and Cu2+), on CO2RR activity. By using a novel approach in the catalyst synthesis we have been able to obtain Cu-based materials with controlled nanostructure, e.g., pore-size distribution, higher surface area, and correlate the catalyst morphology with the selectivity for multi-carbon products. We have associated the formation of CO2RR products with the presence of different active sites on the catalyst surface, a necessary step towards achieving desirable selectivity.
We will also recap the results of a study on the effect of adding a secondary transition metal, e.g., Zn, Ni, and Ag, on electrocatalytic properties of Cu-based catalysts. The rationale behind this approach has been to tune electrocatalytic activity and selectivity via changing the binding strength of the key intermediates, such as *OCHO, *CO, *COOH, *CHO, and *COH.

References

G. Kibria, J. P. Edwards, C. M. Gabardo, C.-T. Dinh, A. Seifitokaldani, D. Sinton, and E. H. Sargent, Adv. Mater. 2019, 31, 1807166.

S. Nitopi, E. Bertheussen, S. B. Scott, X. Liu, A. K. Engstfeld, S. Horch, B. Seger, I. E. L. Stephens, K. Chan, C. Hahn, J. K. Nørskov, T. F. Jaramillo, and I. Chorkendorff, Chem. Rev. 2019, 119, 7610−7672.
Understanding Active Sites in Molecular (Photo)Electrocatalysis through Vibrational Spectroelectrochemistry
Authors: Weidinger Inez Marita , Ly Hoang Khoa , Ramuglia Anthony , Borelli Mino , Querebillo Christine Joy , Dong Renhao , Feng Xinliang , Schwalbe Matthias 
Published: July 2022

Molecularly defined (photo)electrocatalysts have great potential to perform important energy conversion reactions with high efficiency and selectivity. A particular advantage is their modular design, which allows their reactivity to be tailored to a specific reaction. However, to advance their rational development, a deep mechanistic understanding of the catalytic reactions is required. In situ vibrational spectrochemistry, in particular confocal Raman and infrared absorption spectroscopy, is an extremely powerful method to gain deep insights into the structure and reactivity of electrode-immobilized molecular catalytic systems under operando conditions [1]. Since both vibrational spectroscopic techniques have different selection rules, complementary information about the system under operando conditions can be obtained. In my talk, selected research examples will be used to present the different aspects and features of (photo)electrocatalysis that can be visualized using vibrational spectrochemistry. The target systems presented include, on the one hand, porphyrin- and phthalocyanine-based systems for electrocatalytic oxygen and CO2 reduction [2,3] and, on the other hand, conjugated acetylene polymers for photoelectrocatalytic hydrogen evolution [4]. Spectra evaluation under operando conditions allowed us to demonstrate charge separation and ligand binding within these catalysts, identify the active sites during catalysis, and gain insight into the redox properties, reaction intermediates as well as synergistic effects of dual active sites.
[1] H. K. Ly, I. M. Weidinger, Chem. Commun. 2021, 57, 2328-2342
[2] T. R. Ramuglia, V. Budhija, K. H. Ly, M. Marquardt, M. Schwalbe, I. M. Weidinger, ChemCatChem, 2021, 13, 3934.
[3] H. Zhong, M. Ghorbani-Asl, K. H. Ly, J. Zhang, J. Ge, M. Wang, Z. Liao, D. Makarov, E. Zschech, E. Brunner, I.M. Weidinger, J. Zhang, A. V. Krasheninnikov, S. Kaskel, R. Dong, X. Feng, Nat. Comm. 2020, 11, 1409.
[4] M. Borelli, C. J. Querebillo, D. L. Pastoetter, T. Wang, A. Milani, C. Casari, H. K. Ly, F. He, Y. Hou, C. Neumann, A. Turchanin, H. Sun, I. M. Weidinger, X. Feng, Angew. Chemie Int. Ed. 2021, 60 (34), 18876-18881.
(Invited) Gold Electrodes Emersed from Aqueous Electrolytes: A Kelvin Probe and Infrared Spectroscopy Approach
Authors: Kasdorf Giesbrecht Cristiano , Rohwerder Michael 
Published: July 2022

The study of the electric double layer (solid/liquid interface) is of crucial importance for an in-depth understanding electrochemical processes. However, the electrochemical interface (or interphase) is usually buried under a barrier of bulk water which is blocking direct access for most analytical tools. One way to enable direct access is e.g. the emersed electrode concept. For this, electrodes are emersed under potential control from the electrolyte into an inert atmosphere. It was shown in prior works for emersion into UHV [1] and into humid nitrogen [2] that the electrochemical double layer seems to be kept more or less intact during this process. However, thus an electrochemical double layer is obtained that is vertically confined to just one or two monolayers, depending on the humidity of the environment. The Kelvin probe technique can be employed for measuring the resulting electrode potential of such emersed electrodes [3], often providing a linear correlation between applied potentials during the electrochemical polarization and the potentials determined after emersing the sample from the electrolyte [2]. An open question is the role of the amount of water molecules in the double layer on the electrode potential [1,2]. A powerful technique for the investigation of the structure of the water molecules in the double layer region is infrared spectroscopy. Since infrared spectroscopy techniques (using an ATR set-up) can also be applied for characterization of the electrode immersed bulk electrolyte [4], a direct comparison between these two cases is possible.
For this work, NaClO4 and H2SO4 diluted aqueous solutions were used as electrolytes, which both present anions with similar specific adsorption [5]. The Kelvin probe tip was calibrated against an Ag/AgCl/KCl homemade reference electrode [6]. Different atmosphere conditions (relative humidity) were used and their effect on the emersed electrode was investigated by Kelvin probe and IR spectroscopy. Furthermore, studies employing Near Ambient Pressure X-Ray Photoelectron Spectroscopy (NAP-XPS) technique have been conducted in order to detect the presence of anions and cations in the electrochemical double-layer and also for in operando studies with different atmosphere conditions.
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