Deeper mechanistic insights into epitaxial nickelate electrocatalysts for the oxygen evolution reaction

Kiens, Ellen Marijn; Choi, Min‐Ju; Wei, Luhan; Lu, Qiyang; Wang, Le; Baeumer, Christoph

doi:10.1039/d3cc00325f

Cited by 8 publications

(6 citation statements)

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“…The e g orbital of LNO is unit occupied, here 3 d italicz 2 and 3 d x 2 ‐y 2 of e g are generated when the Ni–O octahedron is unstressed. , However, under compressive or tensile strains, the Ni–O octahedron undergoes deformations that result in the splitting of the 3 d italicz 2 and 3 d x 2 ‐y 2 orbitals of e g into higher and lower energy levels. − Within this context, the lower energy orbital offers a more favorable arrangement for the alignment of 3 d x 2 ‐y 2 and 2 p orbitals, necessitating effective strain engineering of the Ni–O octahedron. − In the realm of strain engineering, artificial SLs are commonly employed in TMO epitaxy to create strain-induced effects and amplify interface phenomena, including magnetic and ferroelectric topological states, in complex oxide SLs. − …”

Section: Introductionmentioning

confidence: 99%

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO₃/SrRuO₃ Superlattices

Han,

Guo,

Liu

et al. 2024

J. Phys. Chem. C

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The engineering of the electronic structure in transition metal oxide (TMO) catalysts has emerged as a promising approach to enhance the oxygen evolution reaction (OER) in water-splitting, achieved through precise modulation of the absorption and desorption energies of water intermediates. Among various strategies, strain-induced tunability in electronic structures has shown great potential to significantly improve the performance of the OER performance. In this study, we utilized artificial superlattices (LaNiO 3 ) n /(SrRuO 3 ) m (LNO n /SRO m ) to optimize the surface orbital occupancy of LNO and maximize the strain effect's effectiveness. Our findings indicate that, compared to single-layer LNO films, the LNO 1 /SRO 2 superlattice exhibits an impressive 28% reduction in Tafel slope, along with an approximately 315% enhancement in catalytic current density at 1.65 V for the OER process. The approach of the d 3 x y 2 2 orbital of e g toward the 2p orbital by strain in superlattice is responsible for this OER enhancement, where the centering of e g and 2p orbitals is improved. Our results not only provide a promising strategy for the enhanced OER by engineering the TMO's surface electronic structure, but also showcase the exceptional design of OER catalysts using artificial TMO superlattices.

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Section: Introductionmentioning

confidence: 99%

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO₃/SrRuO₃ Superlattices

Han,

Guo,

Liu

et al. 2024

J. Phys. Chem. C

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“…Recently, manipulating ionic defects in TMOs, such as oxygen vacancies, has been identified as an important pathway for tuning physical properties of TMOs. 24 Oxygen vacancies have also been identified as the possible active sites for thermo-catalytic or electrocatalytic reactions in TMO (electro-)catalysts. 25 If we assume that the charge compensation of created oxygen vacancies is through the reduced oxidation state of TM cations 13 (i.e., "localized" electrons), then measuring the oxidation state of TM cations can directly lead to the concentration of oxygen vacancies (or fraction of defects in total amount of oxide ions).…”

Section: Introductionmentioning

confidence: 99%

“…Perhaps another driving force for the wide application of TM 2p XPS spectra in the research of TMOs is the opportunity to quantify the concentration of ionic defects, especially oxygen vacancies, in TMOs. Recently, manipulating ionic defects in TMOs, such as oxygen vacancies, has been identified as an important pathway for tuning physical properties of TMOs . Oxygen vacancies have also been identified as the possible active sites for thermo-catalytic or electrocatalytic reactions in TMO (electro-)catalysts .…”

Section: Introductionmentioning

confidence: 99%

How to Correctly Analyze 2p X-ray Photoelectron Spectra of 3d Transition-Metal Oxides: Pitfalls and Principles

2024

ACS Nano

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Nanomaterials based on transition-metal oxides (TMOs) that contain late 3d transition metals (e.g., Mn, Fe, Co, Ni) have diverse properties and functionality that are related to the oxidation state of constituent transition-metal (TM) cations. X-ray photoelectron spectroscopy (XPS) of TM 2p orbitals has been widely used to quantify the TM oxidation state of TMOs. However, 2p XPS spectra of late 3d TM cations usually have complicated shapes due to the charge transfer between the TM cation and oxygen ligands (anions), which makes the analysis highly nontrivial. In this article, we will examine the validity of commonly used analysis methods based on either peak fitting or the shift of binding energy (BE). The different origins of the BE shift in XPS spectra will be discussed. We will then introduce a model to reproduce the complex shapes of TM 2p spectra, based on fundamental parameters that describe the TMO electronic structure.

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“…In the AEM, the reaction follows a consecutive pathway via oxygen‐containing intermediates (such as OH*, O*, and OOH*, where * denotes surface adsorbate sites) with surface B‐site TM cations (undergoing associated redox events during charge transfer) representing the active sites. [ 5 ] The adsorption, dissociation, and desorption of oxygen‐containing intermediates play a decisive role in determining OER activity. Several descriptors linked to the electronic properties of perovskite‐based electrocatalysts have been proposed to deepen our understanding of their OER activity and to be able to guide materials design.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Design of Complex Nickelates as Electrocatalysts for the Oxygen Evolution Reaction

Choi

Wang

Stoerzinger

et al. 2023

Advanced Energy Materials

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The oxygen evolution reaction (OER) is a crucial process in electrochemical water splitting, a promising technology to renewably yield hydrogen gas from water. Designing and developing earth‐abundant, efficient, and stable OER electrocatalysts to replace the most widely used but scarce RuO2 and IrO2 are thus of critical interest. Recently, ABO3‐structured perovskite oxides, especially rare‐earth nickelates, are extensively studied for their potential use as OER electrocatalysts. In particular, the epitaxial synthesis of complex oxide thin films allows flexible and precise control over the materials so that their structure–stability–property relationships can be established. Using nickelate thin films as model systems, this review illustrates how epitaxial design allows researchers to test different hypotheses and proposed descriptors, as well as formulate new design principles. Following a brief introduction to the background of OER mechanisms, proposed activity descriptors, and synthesis methods, various epitaxial design strategies are surveyed including strain tuning, composition control, surface termination/orientation selection, defect engineering, and interface design. These have led to precise control over the atomic structures and electronic properties of nickelates which in turn determine their electrochemical performance. Finally, the remaining challenges and perspectives toward a deeper understanding and use of complex oxides as OER catalysts are discussed.

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Deeper mechanistic insights into epitaxial nickelate electrocatalysts for the oxygen evolution reaction

Abstract: Mass production of green hydrogen via water electrolysis requires advancements in the performance of electrocatalysts, especially for the oxygen evolution reaction. In this feature article, we highlight how epitaxial nickelates...

Cited by 8 publications

References 76 publications

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO₃/SrRuO₃ Superlattices

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO₃/SrRuO₃ Superlattices

How to Correctly Analyze 2p X-ray Photoelectron Spectra of 3d Transition-Metal Oxides: Pitfalls and Principles

Epitaxial Design of Complex Nickelates as Electrocatalysts for the Oxygen Evolution Reaction

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Deeper mechanistic insights into epitaxial nickelate electrocatalysts for the oxygen evolution reaction

Abstract: Mass production of green hydrogen via water electrolysis requires advancements in the performance of electrocatalysts, especially for the oxygen evolution reaction. In this feature article, we highlight how epitaxial nickelates...

Cited by 8 publications

References 76 publications

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO3/SrRuO3 Superlattices

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO3/SrRuO3 Superlattices

How to Correctly Analyze 2p X-ray Photoelectron Spectra of 3d Transition-Metal Oxides: Pitfalls and Principles

Epitaxial Design of Complex Nickelates as Electrocatalysts for the Oxygen Evolution Reaction

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Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO₃/SrRuO₃ Superlattices

Enhanced OER Performance through Electronic Structure Engineering in Artificial LaNiO₃/SrRuO₃ Superlattices