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Ordered Mesoporous Metastable α‐MoC1−x with Enhanced Water Dissociation Capability for Boosting Alkaline Hydrogen Evolution Activity

Baek, Du San ; Jung, Gwan Yeong ; Seo, Bora ; Kim, Jin Chul ; Lee, Hyun‐Wook ; Shin, Tae Joo ; Jeong, Hu Young ; Kwak, Sang Kyu ; Joo, Sang Hoon

Advanced functional materials, 2019-07, Vol.29 (28), p.n/a [Periódico revisado por pares]

Hoboken: Wiley Subscription Services, Inc

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  • Título:
    Ordered Mesoporous Metastable α‐MoC1−x with Enhanced Water Dissociation Capability for Boosting Alkaline Hydrogen Evolution Activity
  • Autor: Baek, Du San ; Jung, Gwan Yeong ; Seo, Bora ; Kim, Jin Chul ; Lee, Hyun‐Wook ; Shin, Tae Joo ; Jeong, Hu Young ; Kwak, Sang Kyu ; Joo, Sang Hoon
  • Assuntos: alkaline electrolyzers ; Catalysis ; Catalysts ; Hydrogen evolution ; hydrogen evolution reaction ; mesoporous materials ; molybdenum carbide ; Nanoparticles ; Reaction kinetics ; Surface area ; Tafel slopes ; water dissociation
  • É parte de: Advanced functional materials, 2019-07, Vol.29 (28), p.n/a
  • Descrição: The sluggish reaction kinetics of the alkaline hydrogen evolution reaction (HER) remains an important challenge for water–alkali electrolyzers, which originates predominantly from the additional water dissociation step required for the alkaline HER. In this work, it is demonstrated theoretically and experimentally that metastable, face‐centered‐cubic α‐MoC1−x phase shows superior water dissociation capability and alkaline HER activity than stable, hexagonal‐close‐packed Mo2C phase. Next, high surface area ordered mesoporous α‐MoC1−x (MMC) is designed via a nanocasting method. In MMC structure, the α‐MoC1−x phase facilitates the water dissociation reaction, while the mesoporous structure with high surface area enables a high dispersion of metal NPs and efficient mass transport. As a result, Pt nanoparticles (NPs) supported on MMC (Pt/MMC) show substantially enhanced alkaline HER activity in terms of overpotentials, Tafel slopes, mass and specific activities, and exchange current densities, compared to commercial Pt/C and Pt NPs supported on particulate α‐MoC1−x or β‐Mo2C. Notably, Pt/MMC shows very low Tafel slope of 30 mV dec–1, which is the lowest value among the reported Pt‐based alkaline HER catalysts, suggesting the critical role of MMC in enhancing the HER kinetics. The promotional effect of MMC support in the alkaline HER is further demonstrated with an Ir/MMC catalyst. An ordered mesoporous material constructed with a metastable, face‐centered‐cubic α‐MoC1−x phase is presented as a catalyst promoter and support for metal catalysts to boost sluggish alkaline HER activities. Density functional theory calculations and experimental studies reveal that the enhanced activity originates from excellent water dissociation capability, facile proton adsorption, and efficient mass transport.
  • Editor: Hoboken: Wiley Subscription Services, Inc
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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