bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separating the Effects of Band Bending and Covalency in Hybrid Perovskite Oxide Electrocatalyst Bilayers for Water Electrolysis
Authors: Heymann Lisa , Weber Moritz L , Wohlgemuth Marcus , Risch Marcel , Dittmann Regina , Baeumer Christoph , Gunkel Felix 
Published: February 2024

Testing single crystalline epitaxial thin films as model systems for metal oxide electrocatalysts in the oxygen evolution reaction (OER) enables differentiating the OER descriptors such as crystal facet orientation, surface chemical composition, electronic structure and band bending at the interface to the electrolyte [1,2,3]. We designed single crystalline perovskite oxide bilayer structures to systematically tune the surface electronic structure and the band bending at the electrode/electrolyte interface to understand their role in the OER.
The Co−O covalency in perovskite oxide cobaltites such as La1
−
x SrxCoO3 is believed to impact the electrocatalytic activity during the OER. Additionally, space charge layers through band bending at the interface to the electrolyte may affect the electron transfer into the electrode, complicating the analysis and identification of true OER activity descriptors. Here, we separate the influence of covalency and band bending in hybrid epitaxial bilayer structures of highly OER-active La0.6Sr0.4CoO3 and undoped and less-active LaCoO3. Ultrathin LaCoO3 capping layers of 2−8 unit cells on La0.6Sr0.4CoO3 show intermediate OER activity between La0.6Sr0.4CoO3 and LaCoO3 evidently caused by the increased surface Co−O covalency compared to single LaCoO3 as detected by X-ray photoelectron spectroscopy. A Mott−Schottky analysis revealed low flat band potentials for different LaCoO3 capping layer thicknesses, indicating that no limiting extended space charge layer exists under OER conditions as all catalyst bilayer films exhibited hole accumulation at the surface [1].
The combined X-ray photoelectron spectroscopy and Mott−Schottky analysis of atomically defined bilayer structures thus enables us to differentiate between the influence of the covalency and intrinsic space charge layers, which are indistinguishable in a single physical or electrochemical characterization. Our results emphasize the prominent role of transition metal oxygen covalency in perovskite electrocatalysts and introduce a bilayer approach to fine-tune the surface electronic structure [1].
[1] L. Heymann, M. L. Weber, M. Wohlgemuth, M. Risch, R. Dittmann, C. Baeumer, F. Gunkel (2022) Separating the Effects of Band Bending and Covalency in Hybrid Perovskite Oxide Electrocatalyst Bilayers for Water Electrolysis, ACS Appl. Mater. Interfaces
[2] M. Wohlgemuth, M. L. Weber, L. Heymann, C. Baeumer, F. Gunkel (2022) Activity-Stability Relationships in Oxide Electrocatalysts for Water Electrolysis, Front. Chem.
[3] M. L. Weber, G. Lole, A. Kormanyos, A. Schwiers, L. Heymann, F. D. Speck, T. Meyer, R. Dittmann, S. Cherevko, C. Jooss, C. Baeumer, F. Gunkel, (2022) Atomistic Insights into Activation and Degradation of La0.6Sr0.4CoO3-δ Electrocatalysts under Oxygen Evolution Conditions

Figure 1
Formation of the Heterojunction Based on Titania Modified with Ni and Ag Sulfide Via SILAR Method - Electrochemical and Photoelectrochemical Activity
Authors: Lipinska Wiktoria , Shinnur Manjunath , Grochowska Katarzyna , Crisp Ryan , Siuzdak Katarzyna 
Published: February 2024

The great interest of TiO2 nanotubes (TiNT) is justified by large surface area, high degree of ordering, facilitated charge transport along the nanotube, mechanical strength, strong UV absorption and light scattering due to the pore specific arrangement well as wide range of potential applications in solar cells, photocatalysis and sensors [1]. However, due to the wide energy band gap of TiO2 (3.2 eV) its photoactivity is limited and therefore titania based heterojunction are formed with the photoabsorber being active in the visible range [2]. In line with this strategy, we present electrochemical and photoelectrochemical activity of TiNT modified by NiS and AgS.
The electrode is fabricated via electrochemical anodization of Ti foil, thermal annealing providing anatase phase and finally Successive Ionic Layer Adsorption and Reaction (SILAR) was carried out using silver, nickel and sulfur ions precursor and with different number of deposition cycles. The characteristic Ag-S, Ag-O and S-O peaks appearing on Raman spectra indicating successful SILAR modification. The cyclic voltammetry curves for TiNT, NiS/TiNT, AgS/TiNT and AgS/NiS/TiNT electrode were registered in 0.5 M Na2SO4 (Fig.1a). Peaks found on the anodic branch of the AgS/NiS/TiNT electrode at 0 V and +0.3 V vs. Ag/AgCl/0.1 M KCl are assigned to oxidation of Ag0 to Ag1+ and Ag1+ to Ag2+, respectively. When the scan went towards cathodic direction, peak located at +0.1 V and -0.1 V indicates reduction of Ag2+ to Ag1+ and Ag1+ to Ag0, respectively [3]. Furthermore, the linear voltammetry measurements performed under visible light illumination in 0.5 M Na2SO4 is presented in Fig.1b. The best photoactivity was reached for the AgS/NiS/TiNT electrode when only 5 deposition cycles for each metal precursor was applied. The photocurrent registered at +0.5 V reaches ca. 40 µA/cm2 which is 20 times higher than for pure TiNT.
Summing up, modification of titania nanotubes by nickel and silver sulfides significantly enhanced material photoelectrochemical response under visible light. Moreover, it has been proved that this synergetic effect originated from the titania/metal sulphide heterojunction that can be achieved using SILAR method.
Research is financed by National Science Centre (Poland): Grant no. 2020/39/I/ST5/01781
[1] K. Siuzdak et al. RSC Advances, 5 (2015) 50379, DOI:10.1039/c5ra08407e
[2] S. Chandrasekaran et al. Chemical Society Reviews, 48 (2019) 4178, DOI:10.1039/c8cs00664d
[3] J.R.N. Santos et al. Electrocatalysis, 13 (2022) 713, DOI: 10.1007/s12678-022-00754-2

Figure 1
Effect of pH on the Selectivity of γ-MnO2 Electrocatalysts Towards Oxygen Evolution Reaction in the Presence of Chloride Ions in Alkaline Environment
Authors: Baturina Olga A , Finn Matthew , Weathers Brandice 
Published: February 2024

Pt-Nb anodes utilized in the cathodic protection system onboard of Naval ships generate NaOCl (and eventually Cl2) that (1) limits the materials that can be used in the vicinity of the anodes and (2) has a severe impact on living organisms in the marine environment. The environmentally-friendly oxygen evolution reaction (OER) from H2O is thermodynamically more favorable due to a lower equilibrium potential [1]. However, chlorine evolution successfully competes with the OER due to faster kinetics. One of a few catalysts that demonstrates high selectivity towards the OER in the presence of chloride ions in alkaline environment (pH 12) is g-MnO2 [2]. In this presentation, we will (1) compare activities and selectivities towards the OER of electrodeposited and chemically synthesized g-MnO2 and (2) determine how pH affects selectivity in the pH range from 8 to 12.
References
[1] F. Dionigi, T. Reier, Z. Pawolek, M. Gliech, P. Strasser, Chemsuschem, 9 (2016) 962.
[2] K. Fujimura, T. Matsui, K. Izumiya, N. Kumagai, H. Habazaki, A. Kawashima, K. Asami, K. Hashimoto, Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 267 (1999) 254.
Electrospun Polymer Supported Cux O Nanostructures for CO2 Reduction Reaction
Authors: Elbataioui Adam , Abdalaziz Aljabour , Wurster Stefan , Bautista Daniel , Schlögl Sandra , Eckert Jürgen , Rafailovic Lidija D. 
Published: February 2024

The reduction of carbon dioxide (CO2) to value-added products is a promising approach for mitigating the impact of CO2 emissions on the environment [1]. Copper oxide (CuO) and copper oxide (Cu2O) have been identified as effective catalysts for CO2 reduction reaction (CO2RR) due to their unique electronic properties [2]. Electrospinning is a versatile and efficient technique for the fabrication of high surface area polymer (P) nanofibers which enables a promising range of applications in energy storage and conversion [3].
In this study, we investigate the synthesis of CuxO-incorporated polyacrylonitrile (PAN) and PAN/polyaniline (PANI) nanofibers via electrospinning and evaluate their performance as a catalyst for CO2RR. The CuxO/P nanofibers were characterized by various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy.
The results revealed that CuxO nanoparticles were dispersed on the surface of the polymer nanofibers. The XRD analysis confirmed the presence of crystalline CuxO nanoparticles in the nanofibers. The FTIR spectra indicated that CuxO was successfully incorporated into the polymer nanofibers without new chemical bond formation between CuxO and PAN.
The catalytic performance of CuxO/P nanofibers was evaluated for CO2RR in a three-electrode electrochemical cell. The CuxO/P nanofibers showed a significantly enhanced catalytic activity for CO2RR. Moreover, the CuxO/P nanofibers showed good stability during the electrochemical CO2RR.
The enhanced catalytic performance of CuxO/P nanofibers can be attributed to the unique electronic properties of CuxO nanoparticles, which can facilitate the adsorption and activation of CO2 molecules. Furthermore, the high surface area and porous structure of the polymer nanofibers provide abundant active sites for the CO2RR. The dispersion of CuxO nanoparticles on the surface of the polymer nanofibers can also enhance electron transfer and reduce charge transfer resistance during the CO2RR.
In conclusion, CuxO-incorporated polymer nanofibers were successfully synthesized by electrospinning and showed excellent catalytic activity for CO2RR. The CuxO/P nanofibers exhibited high selectivity and stability for the electrochemical reduction of CO2 to useful chemicals. These findings suggest that CuxO/P nanofibers have great potential as an efficient catalyst for CO2RR and could contribute to the development of sustainable energy conversion and storage systems.
[1] A. Aljabour, D. H. Apaydin, H. Coskun, F. Ozel, M. Ersoz, P. Stadler, N. S. Sariciftci, and M. Kus, ACS Applied Materials & Interfaces, 8 (46), 31695-31701 (2016).
[2] R. W. Abebe, H. Zanling, Z. Pengxiang, H. Liangsheng, A. Didier, Coordination Chemistry Reviews, 454, 214340 (2022).
[3] A. Aljabour, ChemistrySelect
5, 7482 (2020).

Figure 1
The Electronic Structure of Transition Metal (TM) Oxides for the Oxygen Evolution Reaction: The Critical Role of TM 3d Hole State
Authors: Oropeza Freddy , Wang Hongxia , Zhang Kelvin Hongliang , Hofmann Jan Philipp , de la Peña O'Shea Victor A. 
Published: February 2024

Electrolysis of water to produce hydrogen and oxygen is a promising pathway for the storage of renewable energy in form of chemical fuels. The efficiency of the overall process is usually limited by the sluggish kinetics of the oxygen evolution reaction (OER) due to a complex four-electron/proton transfer mechanism. Therefore, the most crucial step for water electrolysis to become a widespread industrial process is to develop efficient electrocatalysts capable of driving the OER at a low overpotential.[1,2]

In this talk, I will summaries the key electronic features that induces high catalytic activity towards the oxygen evolution reaction of trivalent transition metal (TM) oxides with perovskite structure, such as LaCoO3
[3] and LaFeO3.[4] The partial substitution of La for Sr in LaTMO3 results in the oxidation of TM3+ to TM4+ and substantially enhances OER catalytic activity. A comprehensive X-ray spectroscopic study, based on in-situ XPS and XAS, reveals a strong correlation of the enhanced OER catalytic activity with the presence of cations in the 4+ oxidation state. Increasing the concentration of TM cations in the 4+ oxidation state leads to a more covalent TM–O bond due to higher TM 3d–O 2p orbital hybridization and shifts the energy position of the valence band (VB) closer to the Fermi level (E
F). Such an electronic modulation optimizes the surface adsorption energetics of *OH intermediates, contributing to faster OER kinetics. Furthermore, the oxidation of TM3+ to TM4+ creates a new unoccupied state (hole state) below the conduction band, associated with the formation of TM 3d empty electronic states. This hole states reduce the energy barrier for electron transfer associated with the OER, as illustrated in the figure below, thereby facilitating charge transfer at the interface during the reaction.
Figure 1: Key electronic features of transition metal (TM) oxides for the oxygen evolution reaction
References:
[1] M. Cui, X. Ding, X. Huang, Z. Shen, T. L. Lee, F. E. Oropeza, J. P. Hofmann, E. J. M. Hensen, K. H. L. Zhang, Chem. Mater.
2019, 31, 7618.
[2] H. Wang, K. H. L. Zhang, J. P. Hofmann, V. A. de la Peña O’Shea, F. E. Oropeza, J. Mater. Chem. A
2021, 9, 19465.
[3] Z. Shen, M. Qu, J. Shi, F. E. Oropeza, V. A. de la Peña O’Shea, G. Gorni, C. M. Tian, J. P. Hofmann, J. Cheng, J. Li, K. H. L. Zhang, J. Energy Chem.
2022, 65, 637.
[4] Z. Shen, Y. Zhuang, W. Li, X. Huang, F. E. Oropeza, E. J. M. Hensen, J. P. Hofmann, M. Cui, A. Tadich, D. Qi, J. Cheng, J. Li, K. H. L. Zhang, J. Mater. Chem. A
2020, 8, 4407.

Figure 1
Investigations on the Initial-Stages of Lithium Deposition/Dissolution Processes in Sulfolane Based Electrolytes
Authors: Genov Ivan , Tesfaye Alexander , Ivanov Svetlozar , Bund Andreas 
Published: February 2024

Li metal could be the ideal anode for rechargeable battery technologies, due to its negative redox potential (ca. -3 V vs. SHE), high specific capacity (3860 mAh g−1), and low density (0.534 g cm−3) [1-3]. Recent advances show a new design concept where there are no initial active materials in the anode (no carbon, Si, or Li metal) and the corresponding Li quantity is directly deposited on the current collector during charging. This approach will result in important practical advantages such as enhanced volumetric and gravimetric specific energies, ease of manufacturing and reduced complexity/safety concerns of the recycling process (ideally Li is completely removed in the discharged state). However, the applicability of the Li-metal batteries is constrained by the nonuniform lithium deposition, accompanied by dendrite growth and the formation of dead lithium during long-term cycling, which lead to low Coulombic efficiency and even cell failure [2]. The initial structure and morphology of the Li deposit has a vital influence on the later progression of the Li layer [4]. This underpins the importance of a fundamental understanding of the electrodeposition process. However, the presence of a solid-electrolyte interphase (SEI) makes such investigations difficult, since after the transport of the Li ions through the SEI, a subsequent charge transfer and nucleation growth process at the substrate-SEI interface, instead of substrate-liquid electrolyte interface occurs. This contribution will discuss lithium electrodeposition in a sulfolane based, localized high concentrated electrolyte system. Possible phase formation mechanisms as well as kinetic and thermodynamic aspects during the initial stages of the process are studied by classical electrochemical methods (Fig. 1, left). Furthermore, the mass-charge balance during deposition and stripping was monitored (Fig. 1, right) via in-situ microgravimetry (electrochemical quartz crystal microbalance). In the contribution we will discuss these transients in terms of lithium layer growth and SEI formation.

References:

[1] X. Cheng et al., (2017) Chemical Reviews, 117 (15), p. 10403-10473.
[2] J. Cui et al., (2017) Chinese Chemical Letters, 28 (12), p. 2171-2179.
[3] Z. Hu et al., (2020) Frontiers in chemistry 8, p. 409.
[4] A. Pei et al., (2017) Nano Letters, 17 (2), p. 1132–1139.

Figure 1
(Invited) Engineering Local Chemical Environments in Electrolytes and at Electrode-Electrolyte Interface for Efficient Aqueous Batteries
Authors: Lukatskaya Maria R. 
Published: February 2024

Electrolytes are an essential component of energy storage devices. Electrolyte composition has a significant impact on the environmental footprint, safety, price and performance of a battery. Aqueous electrolytes are non-flammable and can offer safer battery operation and lower toxicity. However, they suffer from a smaller electrochemical stability window compared to traditional organic electrolytes, which leads to lower energy density. To circumvent the small electrochemical stability window, highly concentrated “water-in-salt” (WIS) electrolytes, which demonstrate significantly wider stability window, were proposed and successfully applied to various aqueous energy storage systems including Li-ion and Zn metal batteries that are highly attractive for grid energy storage. However, since WIS electrolytes require large amounts of salt (often toxic) and have dramatically increased viscosity, it in turn limits their transport properties, charge-discharge rates, and usability in batteries.
In this talk, the use of highly concentrated "water-in-salt" (WIS) electrolytes as a means of achieving increased charging efficiency and a wider stability window will be discussed in the context of aqueous Li-ion and Zn metal batteries. Further, we elaborate the role of cation solvation environment, electrolyte structure and hydrogen bonding on the physicochemical properties and electrochemical response of the system. We show that electrolyte composition affects the interfacial kinetics of Zn plating/stripping as well as the kinetics of the parasitic processes of electrolyte decomposition. Finally, we discuss how relatively dilute electrolytes can be engineered for efficient aqueous batteries.

References

Suo, O. Borodin, T. Gao, M. Olguin, J. Ho, X. Fan, C. Luo, C. Wang and K. Xu, Science, 2015, 350, 938

Yamada, K. Usui, K. Sodeyama, S. Ko, Y. Tateyama and A. Yamada, Nat. Energy, 2016, 1, 16129

R. Lukatskaya, J.I. Feldblyum, D.G. Mackanic, F. Lissel, D.L. Michels, Y. Cui, Z. Bao, Energy Environ. Sci., 2018, 11, 2876-2883

D.G. Vazquez, T. P. Pollard, J. Mars, J.M. Yoo, H.G. Steinrück, S. E. Bone, O. V. Safonova, M. F. Toney, O. Borodin, M.R. Lukatskaya, Energy Environ. Sci., 2023, DOI: 10.1039/D3EE00205E
Combined Operando Investigations Reveal Correlation between Formation Parameters and Transport Mechanisms in Solid Electrolyte Interphases of Lithium-Ion Battery Anodes
Authors: Stich Michael , Valdes Landa Jesus Eduardo , Pantenburg Isabel , Roling Bernhard , Bund Andreas 
Published: February 2024

Despite its thickness being only in the nanometer range, the solid electrolyte interphase (SEI) of lithium-ion battery anodes has proven to be a crucial component, contributing critically to the battery’s longevity and long-term rate capability. This is due to the SEI’s passivating properties, protecting the battery electrolyte from further decomposition during operation while maintaining a good conductivity for lithium ions to be intercalated into the active anode material. Notwithstanding prolonged scientific efforts, a reliable SEI characterization is still very challenging, due to its fragile and inherently unstable nature which can easily lead to the introduction of artifacts in its evaluation, when dried, rinsed, or exposed to ambient atmospheric conditions. Thus, the relation between SEI formation parameters and the resulting morphological, compositional, and electrochemical properties is still poorly understood.
To overcome the limitations of often-employed ex-situ methods, we developed an interlocked combination of several non-destructive operando characterization methods consisting of atomic force microscopy (AFM), electrochemical quartz-crystal microbalance (EQCM) and electrochemical impedance spectroscopy (EIS) to provide a plethora of information on the SEI’s morphological evolution, mass and thickness development and its viscoelastic and electrochemical properties like charge transfer resistance. All this information is gathered in the same electrochemical cell during the SEI formation on carbon model electrodes in typical LIB electrolytes containing 1 M LiPF6 in various carbonate mixtures.
The combination of AFM, EQCM and EIS data gives us the opportunity to correlate the different growth modes during formation and resulting compositions of the SEI with its dominant transport mechanisms. Additional redox probe experiments help to further distinguish the transport parameters for lithium ions, solvent molecules, and redox molecules. A better understanding of these correlations allows battery researchers to find optimized SEI formation procedures and SEI forming additives, which reduce the formation duration during battery production and can thus contribute to lowering costs of lithium-ion batteries.
Theoretical and Experimental Performance Characterization of Battery Anodes Comprised of Coal Derived Graphite
Authors: Paul Abigail , Magee Regan , Wilczewski Warren , Wolfe Kody D , Wichert Nathan , Wang Fengkun , Trembly Jason , Staser John A. , Garrick Taylor R. 
Published: February 2024

As demand for energy storage expands, securing reliable supply-chains for raw battery materials is critical in mitigating the threats of delayed manufacturing and inflated manufacturing costs. These issues have pushed researchers and industry to consider alternative sources for traditional lithium-ion battery materials, such as graphite. Commonly available sources of graphite for Li-ion anodes include natural graphite and petroleum coke derived synthetic graphite. While many carbon sources have been studied, most require complicated processing and result in sub-par graphite anode materials. This talk highlights raw coal and coal derived materials as promising graphite sources thanks to their abundance of sp2 hybridized carbon, resulting in simpler processing, and low material costs.
We show that coal derived graphite can be implemented as a lithium-ion anode, however, many chemical, microstructural, and morphological considerations are necessary to compare with commercial graphite performance. We will experimentally compare the morphology at the microstructure for graphite from various carbon sources, and then apply the virtual microstructure analysis method as detailed by Lopata et al to quantify potential differences between the anode microstructures with respect to effective active material particle size (diffusion length calculation), the electrochemical surface area, and the tortuosity of the liquid phase domain. These calculations from representative 3D microstructures can then be extended to a porous electrode model as detailed in Garrick et al to probe the impact in ionic, kinetic, and ohmic losses in the system.
References

Joseph S. Lopata et al 2023 J. Electrochem. Soc.
170 020530

Taylor R. Garrick et al 2021 J. Electrochem. Soc.
168 010530