Engineering metal–metal oxide surfaces for high-performance oxygen reduction on Ag–Mn electrocatalysts

Zeledón, José A. Zamora; Gunasooriya, G. T. Kasun Kalhara; Kamat, Gaurav A.; Kreider, Melissa E.; Ben-Naim, Micha; Hubert, McKenzie A.; Acosta, Jaime E. Avilés; Nørskov, Jens K.; Stevens, Michaela Burke; Jaramillo, Thomas F.

doi:10.1039/d2ee00047d

Cited by 30 publications

(39 citation statements)

References 77 publications

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“…Mn 2 O 3 demonstrates a high theoretical activity toward ORR in agreement with the experimental literature . Interestingly, the theoretical activity of MnSb 2 O 6 (001) surface is higher than the previously studied Mn 2 O 3 (110) surface and comparable with the Mn 2 O 3 (100) surface . A comparison of the Bader charge of Mn (Figure S8) in the MnSb 2 O 6 as well the reference materials (MnO, Mn 3 O 4 , Mn 2 O 3 , and MnO 2 ) with known valence state suggests that the oxidation state of MnSb 2 O 6 is close to +2.…”

Section: Resultssupporting

confidence: 85%

“…11 Interestingly, the theoretical activity of MnSb 2 O 6 (001) surface is higher than the previously studied Mn 2 O 3 (110) surface and comparable with the Mn 2 O 3 (100) surface. 26 A comparison of the Bader charge of Mn (Figure S8) in the MnSb 2 O 6 as well the reference materials (MnO, Mn 3 O 4 , Mn 2 O 3 , and MnO 2 ) with known valence state suggests that the oxidation state of MnSb 2 O 6 is close to +2. We further evaluated the ORR activity of MnO and obtained a U L of 0.77 V for MnO(100), which is slightly lower than the 0.81 V for MnSb 2 O 6 (001).…”

Section: Resultsmentioning

confidence: 92%

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First-Row Transition Metal Antimonates for the Oxygen Reduction Reaction

et al. 2022

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The development of inexpensive and abundant catalysts with high activity, selectivity, and stability for the oxygen reduction reaction (ORR) is imperative for the widespread implementation of fuel cell devices. Herein, we present a combined theoretical−experimental approach to discover and design first-row transition metal antimonates as excellent electrocatalytic materials for the ORR. Theoretically, we identify first-row transition metal antimonatesMSb 2 O 6 , where M = Mn, Fe, Co, and Nias nonprecious metal catalysts with good oxygen binding energetics, conductivity, thermodynamic phase stability, and aqueous stability. Among the considered antimonates, MnSb 2 O 6 shows the highest theoretical ORR activity based on the 4e − ORR kinetic volcano. Experimentally, nanoparticulate transition metal antimonate catalysts are found to have a minimum of a 2.5-fold enhancement in intrinsic mass activity (on transition metal mass basis) relative to the corresponding transition metal oxide at 0.7 V vs RHE in 0.1 M KOH. MnSb 2 O 6 is the most active catalyst under these conditions, with a 3.5-fold enhancement on a per Mn mass activity basis and 25-fold enhancement on a surface area basis over its antimony-free counterpart. Electrocatalytic and material stability are demonstrated over a 5 h chronopotentiometry experiment in the stability window identified by theoretical Pourbaix analysis. This study further highlights the stable and electrically conductive antimonate structure as a framework to tune the activity and selectivity of nonprecious metal oxide active sites for ORR catalysis.

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 92%

First-Row Transition Metal Antimonates for the Oxygen Reduction Reaction

et al. 2022

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“…The most stable Fe and Ni antimonates, as well as their equimolar mixes with Mn, have the rutile (MSb 2 O 6 ) structure . The theoretical activities of Mn 2 O 3 (100) and (110) surfaces were taken from a previous study . Among the considered surfaces with equal metal concentration, the Mn–Cr system shows the highest calculated ORR activity (Figure B and Table S2).…”

Section: Resultsmentioning

confidence: 99%

“…14 The theoretical activities of Mn 2 O 3 (100) and (110) surfaces were taken from a previous study. 54 Among the considered surfaces with equal metal concentration, the Mn−Cr system shows the highest calculated ORR activity (Figure 2B and Table S2). Mn and the secondary transition metals are considered as active sites, with both Cr and Fe sites showing higher activity than Mn on some facets.…”

Section: Tuning Materials Properties and Intrinsic Activity: Mixing M...mentioning

confidence: 99%

Strategies for Modulating the Catalytic Activity and Selectivity of Manganese Antimonates for the Oxygen Reduction Reaction

et al. 2022

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Strategies for improving the performance of nonprecious metal catalysts for the oxygen reduction reaction (ORR) can facilitate the cost-effective deployment of fuel cell devices. Electrocatalyst performance is typically improved via two approaches: increasing the number of active sites and increasing the intrinsic activity of the active site. Herein, we utilize these two methods of improving performance for MnSb 2 O 6 , which we have recently shown to be a promising ORR catalyst due to improvements in per-metal-site activity in the antimonate framework. First, electrode engineering is used to investigate the role of mass and conductive support loading in the observed ORR performance and selectivity. The apparent 2-electron selectivity is found to decrease with increases in mass and/or conductive support loading, indicating that rotating ring disk electrode studies do not necessarily measure the intrinsic selectivity of the catalyst. Second, theoretical calculations are used to identify Cr, Fe, and Ni as promising first-row transition metals for improving the intrinsic activity of MnSb 2 O 6 . Experimentally, the addition of Cr results in 3-fold and 2-fold increases in the mass and specific activities at 0.7 V vs the reversible hydrogen electrode, respectively. This enhancement is attributed to the modulation of the active site structure and Mn oxidation state with the addition of Cr. Through these studies, we gain insight into the intrinsic and extrinsic factors that govern ORR performance.

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“…Due to their alkaline environment, AEM FCs have the potential to stabilize a larger range of materials, including non-PGMs. Combined efforts from the TRI consortium have refined the approach of alloy engineering by demonstrating significant ORR activity enhancements on Ag–Cu, 47 Ag–Mn, 48 and Ag–Pd 37 alloys, in 0.1 M KOH, compared to their parent materials. Ag–Pd alloys were systematically synthesized using the same e-beam PVD co-deposition technique resulting in stable electrocatalysts with state-of-the-art intrinsic ORR activities (Fig.…”

Section: Conventional Approach: Fundamental Activity Relationships Gu...mentioning

confidence: 99%

New challenges in oxygen reduction catalysis: a consortium retrospective to inform future research

Stevens

Kreider

Price

et al. 2022

Energy Environ. Sci.

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Engineering metal–metal oxide surfaces for high-performance oxygen reduction on Ag–Mn electrocatalysts

Abstract: Diverse Ag–MnOx surface sites/structures in Ag–Mn electrocatalysts afford robust local electronic structures tuned for efficient oxygen reduction.

Cited by 30 publications

References 77 publications

First-Row Transition Metal Antimonates for the Oxygen Reduction Reaction

First-Row Transition Metal Antimonates for the Oxygen Reduction Reaction

Strategies for Modulating the Catalytic Activity and Selectivity of Manganese Antimonates for the Oxygen Reduction Reaction

New challenges in oxygen reduction catalysis: a consortium retrospective to inform future research

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