Mechanistic Aspects of the Electrocatalytic Oxygen Evolution Reaction over Ni−Co Oxides

Negahdar, Leila; Zeng, Feng; Palkovits, Stefan; Broicher, Cornelia; Palkovits, Regina

doi:10.1002/celc.201901265

Cited by 110 publications

(90 citation statements)

References 50 publications

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“…These low Tafel slope values indicate that the second reaction of the OER mechanism in alkaline media was rate-determining [ 56 ]. The low Tafel slope also indicates a strong adsorption of surface intermediates in the primary step, hampering the following step which became rate limiting [ 57 ]. In summary, the different Co-doped PAN-N samples showed similar surface adsorption energies, being almost independent of the distinct Co loading.…”

Section: Resultsmentioning

confidence: 99%

Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

et al. 2021

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We report a new class of polyacrylonitrile (PAN)-based Co-N-doped carbon materials that can act as suitable catalyst for oxygen evolution reactions (OER). Different Co loadings were mechanochemically added into post-consumed PAN fibers. Subsequently, the samples were treated at 300 °C under air (PAN-A) or nitrogen (PAN-N) atmosphere to promote simultaneously the Co3O4 species and PAN cyclization. The resulting electrocatalysts were fully characterized and analyzed by X-ray diffraction (XRD) and photoelectron spectroscopy (XPS), transmission (TEM) and scanning electron (SEM) microscopies, as well as nitrogen porosimetry. The catalytic performance of the Co-N-doped carbon nanomaterials were tested for OER in alkaline environments. Cobalt-doped PAN-A samples showed worse OER electrocatalytic performance than their homologous PAN-N ones. The PAN-N/3% Co catalyst exhibited the lowest OER overpotential (460 mV) among all the Co-N-doped carbon nanocomposites, reaching 10 mA/cm2. This work provides in-depth insights on the electrocatalytic performance of metal-doped carbon nanomaterials for OER.

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Section: Resultsmentioning

confidence: 99%

Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

et al. 2021

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“…For complex reactions like aerobic oxidation, co-adsorbate interactions between, for example, O 2 and the substrate, can lead to non-Langmuirian adsorption and attenuate substrate reaction orders. 25,26,27,28,29 The SC model provides insight into the origin of the observed fractional order and the differential contributions to it from each half reaction. In particular, comparing the FA polarization curves at both concentrations (Fig.…”

Section: Resultsmentioning

confidence: 99%

Thermochemical Aerobic Oxidation Catalysis in Water Proceeds via Coupled Electrochemical Half-Reactions

Ryu

Bregante

Howland

et al. 2021

Preprint

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Heterogeneous aqueous-phase aerobic oxidations are an important emerging class of catalytic transformations, particularly for upgrading next generation bio-derived substrates. The mechanism of these reactions and the precise role of O2 in particular remains unclear. Herein, we test the hypothesis that thermochemical aerobic oxidation proceeds via two coupled electrochemical half-reactions for oxygen reduction and substrate oxidation. We collect electrochemical and thermochemical data on common noble metal catalysts under identical reaction/transport environments, and find that the electrochemical polarization curves of the O2 reduction and the substrate oxidation half-reaction closely predict the mixed potential of the catalyst measured in operando during thermochemical catalysis across 13 diverse variables spanning reaction conditions, catalyst composition, reactant identity, and pH. Additionally, we find that driving the oxidation half-reaction reaction electrochemically in the absence of O2 at the mixed potential leads to very similar rates and selectivities as for the thermochemical reaction in all cases examined. These findings strongly indicate that the role of O2 in thermochemical aerobic oxidation is solely as an electron scavenger that provides an incipient electrochemical driving force for substrate oxidation. These studies provide a quantitative and predictive link between thermochemical and electrochemical catalysis, thereby enabling the rational design of new thermochemical liquid-phase aerobic oxidation schemes by applying the principles of electrochemistry.

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“…For complex reactions like aerobic oxidation, co-adsorbate interactions between, for example, O2 and the substrate, can lead to non-Langmuirian adsorption and attenuate substrate reaction orders. 25,26,27,28,29 The SC model provides insight into the origin of the observed fractional order and the differential contributions to it from each half reaction. In particular, comparing the FA polarization curves at both concentrations (Fig.…”

Section: The Short Circuit Model Provides a Detailed Picture Of How Rmentioning

confidence: 99%

Thermochemical Aerobic Oxidation Catalysis in Water Proceeds via Coupled Electrochemical Half-Reactions

Ryu¹,

Bregante²,

Howland³

et al. 2021

Preprint

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<div> Heterogeneous aqueous-phase aerobic oxidations are an important emerging class of catalytic transformations, particularly for upgrading next generation bio-derived substrates. The mechanism of these reactions and the precise role of O2 in particular remains unclear. Herein, we test the hypothesis that thermochemical aerobic oxidation proceeds via two coupled electrochemical half-reactions for oxygen reduction and substrate oxidation. We collect electrochemical and thermochemical data on common noble metal catalysts under identical reaction/transport environments, and find that the electrochemical polarization curves of the O2 reduction and the substrate oxidation half-reaction closely predict the mixed potential of the catalyst measured in operando during thermochemical catalysis across 13 diverse variables spanning reaction conditions, catalyst composition, reactant identity, and pH. Additionally, we find that driving the oxidation half-reaction reaction electrochemically in the absence of O2 at the mixed potential leads to very similar rates and selectivities as for the thermochemical reaction in all cases examined. These findings strongly indicate that the role of O2 in thermochemical aerobic oxidation is solely as an electron scavenger that provides an incipient electrochemical driving force for substrate oxidation. These studies provide a quantitative and predictive link between thermochemical and electrochemical catalysis, thereby enabling the rational design of new thermochemical liquid-phase aerobic oxidation schemes by applying the principles of electrochemistry. </div>

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Mechanistic Aspects of the Electrocatalytic Oxygen Evolution Reaction over Ni−Co Oxides

Cited by 110 publications

References 50 publications

Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

Thermochemical Aerobic Oxidation Catalysis in Water Proceeds via Coupled Electrochemical Half-Reactions

Thermochemical Aerobic Oxidation Catalysis in Water Proceeds via Coupled Electrochemical Half-Reactions

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