Dataset Information

Modulating Ni/Ce Ratio in Ni_yCe_100-yO_x Electrocatalysts for Enhanced Water Oxidation.

ABSTRACT: Oxygen evolution reaction (OER) is the key reaction for water splitting, which is used for hydrogen production. Oxygen vacancy engineering is an effective method to tune the OER performance, but the direct relationship between the concentration of oxygen vacancy and OER activity is not well understood. Herein, a series of Ni_yCe_100-yO_x with different concentration of oxygen vacancies were successfully synthesized. The larger concentration of oxygen vacancies in Ni₇₅Ce₂₅O_x and Ni₅₀Ce₅₀O_x result in their lower Tafel slopes, small mass-transfer resistance, and larger electrochemical surface areas of the catalysts, which account for the higher OER activities for these two catalysts. Moreover, with a fixed current density of 10 mA/cm², the potential remains stable at 1.57 V for more than 100 h, indicating the long-term stability of the Ni₇₅Ce₂₅O_x catalyst.

SUBMITTER: Yu J

PROVIDER: S-EPMC7914620 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Modulating Ni/Ce Ratio in NiyCe100-yOx Electrocatalysts for Enhanced Water Oxidation.

Yu Jun J Cao Qi Q Qiu Chen C Chen Lei L Delaunay Jean-Jacques JJ

Nanomaterials (Basel, Switzerland) 20210209 2

Oxygen evolution reaction (OER) is the key reaction for water splitting, which is used for hydrogen production. Oxygen vacancy engineering is an effective method to tune the OER performance, but the direct relationship between the concentration of oxygen vacancy and OER activity is not well understood. Herein, a series of NiyCe100-yOx with different concentration of oxygen vacancies were successfully synthesized. The larger concentration of oxygen vacancies in Ni ...[more]

PMID: 33572183

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Project description:The development of efficient and stable earth-abundant water oxidation catalysts is vital for economically feasible water-splitting systems. Cobalt phosphate (CoPi)-based catalysts belong to the relevant class of nonprecious electrocatalysts studied for the oxygen evolution reaction (OER). In this work, an in-depth investigation of the electrochemical activation of CoPi-based electrocatalysts by cyclic voltammetry (CV) is presented. Atomic layer deposition (ALD) is adopted because it enables the synthesis of CoPi films with cobalt-to-phosphorous ratios between 1.4 and 1.9. It is shown that the pristine chemical composition of the CoPi film strongly influences its OER activity in the early stages of the activation process as well as after prolonged exposure to the electrolyte. The best performing CoPi catalyst, displaying a current density of 3.9 mA cm-2 at 1.8 V versus reversible hydrogen electrode and a Tafel slope of 155 mV/dec at pH 8.0, is selected for an in-depth study of the evolution of its electrochemical properties, chemical composition, and electrochemical active surface area (ECSA) during the activation process. Upon the increase of the number of CV cycles, the OER performance increases, in parallel with the development of a noncatalytic wave in the CV scan, which points out to the reversible oxidation of Co2+ species to Co3+ species. X-ray photoelectron spectroscopy and Rutherford backscattering measurements indicate that phosphorous progressively leaches out the CoPi film bulk upon prolonged exposure to the electrolyte. In parallel, the ECSA of the films increases by up to a factor of 40, depending on the initial stoichiometry. The ECSA of the activated CoPi films shows a universal linear correlation with the OER activity for the whole range of CoPi chemical composition. It can be concluded that the adoption of ALD in CoPi-based electrocatalysis enables, next to the well-established control over film growth and properties, to disclose the mechanisms behind the CoPi electrocatalyst activation.

Dataset Information

Modulating Ni/Ce Ratio in Ni_yCe_100-yO_x Electrocatalysts for Enhanced Water Oxidation.

Publications

Modulating Ni/Ce Ratio in Ni<sub>y</sub>Ce<sub>100-y</sub>O<sub>x</sub> Electrocatalysts for Enhanced Water Oxidation.

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