Assessing Stability of Transition Metal Nitrides in Aqueous Environments: The Case of Molybdenum, Iron, Vanadium and Nickel Nitride

Matanović, Ivana; Garzón, Fernando H.

doi:10.1149/1945-7111/ab7a8b

Cited by 10 publications

(22 citation statements)

References 35 publications

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“…This hypothesis is in agreement with a recently published analysis of solution thermochemical data, showing that Fe 2 N is stable in strongly alkaline and reducing conditions, otherwise decomposing to yield Fe 2 O 3 or Fe 3 O 4. However, we cannot exclude the possibility that the FeO 1– x N x is formed, at least in part, by in situ reaction between ε-Fe 2+ x N and/or γ″-FeN with the NaOH byproduct. The presence of FeO 1– x N x from this synthesis in substantial yield may also prove exploitable for metastable oxynitride synthesis.…”

Section: Resultsmentioning

confidence: 97%

Low-Temperature Nitridation of Fe₃O₄ by Reaction with NaNH₂

et al. 2021

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Low-temperature soft chemical synthesis routes to transition-metal nitrides are of interest as an alternative to conventional high-temperature ammonolysis reactions involving large volumes of chemotoxic NH 3 gas. One such method is the reaction between metal oxides and NaNH 2 at ca. 200 °C to yield the counterpart nitrides; however, there remains uncertainty regarding the reaction mechanism and product phase assemblage (in particular, noncrystalline components). Here, we extend the chemical tool box and mechanistic understanding of such reactions, demonstrating the nitridation of Fe 3 O 4 by reaction with NaNH 2 at 170–190 °C, via a pseudomorphic reaction. The more reduced Fe 3 O 4 precursor enabled nitride formation at lower temperatures than the previously reported equivalent reaction with Fe 2 O 3 . The product phase assemblage, characterized by X-ray diffraction, thermogravimetric analysis, and 57 Fe Mössbauer spectroscopy, comprised 49–59 mol % ε-Fe 2+ x N, accompanied by 29–39 mol % FeO 1– x N x and 8–14 mol % γ″ - FeN. The oxynitride phase was apparently noncrystalline in the recovered product but could be crystallized by heating at 180 °C. Although synthesis of transition-metal nitrides is achieved by reaction of the counterpart oxide with NaNH 2 , it is evident from this investigation that the product phase assemblage may be complex, which could prove a limitation if the objective is to produce a single-phase product with well-defined electrical, magnetic, or other physical properties for applications. However, the significant yield of the FeO 1– x N x oxynitride phase identified in this study opens the possibility for the synthesis of metastable oxynitride phases in high yield, by reaction of a metal oxide substrate with NaNH 2 , with either careful control of H 2 O concentration in the system or postsynthetic hydrolysis and crystallization.

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Section: Resultsmentioning

confidence: 97%

Low-Temperature Nitridation of Fe₃O₄ by Reaction with NaNH₂

et al. 2021

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“…1 × 10 –8 mol cm –2 s –1 . Follow-up studies of these metal nitrides, however, indicate negligible activity for e-NRR and instead confirm that detected NH 3 arises from metal nitride decomposition under reducing conditions. , A computational study of the thermodynamic stability of metal nitrides, including Mo, V, Fe, and Ni nitrides in aqueous environments, identified limited regions of stability across pH values and applied potentials . For example, the relative stabilities of cubic Mo 2 N and hexagonal MoN change as a function of pH and applied potential.…”

Section: Experimental E-nrr Performance Of Metal Oxynitrides Oxides A...mentioning

confidence: 95%

“…Of these various materials, metal nitrides are interesting in that they can incorporate dinitrogen into vacant surface lattice sites via a Mars–van Krevelen (MvK) mechanism to form ammonia while potentially suppressing HER. Nonetheless, metal nitrides suffer from thermodynamically driven decomposition under e-NRR conditions and still do not have acceptable activity. , …”

Section: Introductionmentioning

confidence: 99%

“…Nonetheless, metal nitrides suffer from thermodynamically driven decomposition under e-NRR conditions and still do not have acceptable activity. 26,27 Some of the activity, selectivity, and stability limitations of metal nitrides could be addressed by transforming them to their partial oxide counterparts, metal oxynitrides (A x O w N z or A x B y O w N z , where A and B are usually transition metals; Figure 1). 28,29 Metal oxynitrides contain both O and N anions in varying compositions.…”

Section: Introductionmentioning

confidence: 99%

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Metal Oxynitrides for the Electrocatalytic Reduction of Nitrogen to Ammonia

et al. 2022

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The successful deployment of technologies for the electrocatalytic nitrogen reduction reaction (e-NRR) to synthesize ammonia would enable distributed ammonia production with lower greenhouse gas emissions compared to the Haber−Bosch process. However, electrocatalysts that can readily activate N 2 , promote selective ammonia formation over the competing hydrogen evolution reaction, and maintain stability under reaction conditions are needed to enable this technology. Herein, we give our perspective on metal oxynitrides (A x B y O w N z ) as an emerging and underexplored materials class for e-NRR. We contrast the activity, selectivity, and stability of metal oxynitrides with those of their metal nitride and metal oxide counterparts. We discuss the different possible e-NRR reaction mechanisms on metal oxynitrides, emphasize challenges related to using metal oxynitrides for e-NRR, and provide an outlook for future research. Ultimately, the huge design space of metal oxynitrides is ripe for exploration to find catalyst formulations that overcome some of the limitations of traditional metal oxides and metal nitrides for e-NRR.

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“…Thus, the limited stability of the metal nitrides places severe constraints for their use in aqueous electrocatalytic applications. Changing pH from acidic to alkaline decreases the stability of VN and the oxide formation potentials shift to more negative values [69]. Later, the high oxidation tendency was reported for surface vanadium atoms of nanocrystalline VN material prepared by thermal decomposition of the V(acac) 3 precursor using oleylamine as a surface stabilizing agent [70].…”

Section: Introductionmentioning

confidence: 99%

Exploring of catalytic oxygen reduction reaction activity of lattice carbons of vanadium and niobium doped nitrogen codoped carbon nanotubes by density functional theory

Kuzmin

Shainyan

2022

Int J of Quantum Chemistry

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The oxygen electroreduction mechanism on the V‐ and Nb‐doped nitrogen‐codoped (6,6)armchair carbon nanotube with incorporated MN4 fragment has been studied using the ωB97XD and PBE density functional theory approaches. The metal center in MN4 fragment and the adjacent NCCN double bond (C2 site) of the support have been revealed as active centers. The metal active centers turned out to be irreversibly oxidized at the first step of ORR affording stable O*, 2O*, or O*HO* adsorbates depending on the applied electrode potential U, that makes them no longer active in ORR. Therefore, the C2 site comes at the forefront in ORR catalysis. Among the metal oxidized forms M(O)N4, M(O)(O)N4, and M(O)(OH)N4CNT, the C2 site of the latter turned out to be most active for 4e dissociative ORR. For both metals the last protonation/electron transfer step, HO* + H* → H2O, is the rate‐limiting step. The alternative hydrogen peroxide formation is not only thermodynamically less favorable but also kinetically slower than the 4e dissociative ORR route on the C2 site of model M(O)(OH)N4CNT catalyst.

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Assessing Stability of Transition Metal Nitrides in Aqueous Environments: The Case of Molybdenum, Iron, Vanadium and Nickel Nitride

Cited by 10 publications

References 35 publications

Low-Temperature Nitridation of Fe₃O₄ by Reaction with NaNH₂

Low-Temperature Nitridation of Fe₃O₄ by Reaction with NaNH₂

Metal Oxynitrides for the Electrocatalytic Reduction of Nitrogen to Ammonia

Exploring of catalytic oxygen reduction reaction activity of lattice carbons of vanadium and niobium doped nitrogen codoped carbon nanotubes by density functional theory

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Assessing Stability of Transition Metal Nitrides in Aqueous Environments: The Case of Molybdenum, Iron, Vanadium and Nickel Nitride

Cited by 10 publications

References 35 publications

Low-Temperature Nitridation of Fe3O4 by Reaction with NaNH2

Low-Temperature Nitridation of Fe3O4 by Reaction with NaNH2

Metal Oxynitrides for the Electrocatalytic Reduction of Nitrogen to Ammonia

Exploring of catalytic oxygen reduction reaction activity of lattice carbons of vanadium and niobium doped nitrogen codoped carbon nanotubes by density functional theory

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Low-Temperature Nitridation of Fe₃O₄ by Reaction with NaNH₂

Low-Temperature Nitridation of Fe₃O₄ by Reaction with NaNH₂