Low-frequency inductive features in the electrochemical impedance spectra of mass-transport limited redox reactions

Choudhury, Debittree; Das, Rubul; Maurya, Rajan; Gupta, Geetanksha; Neergat, Manoj

doi:10.1039/d3cp00047h

“…Once the current density recovers to 1 mA cm −2 , the discharge voltage returns to 1.34 V, implying the prominent rate performance of the ZAB with FePc‐{PW 12 }@NT cathode. The electrochemical impedance spectroscopy (EIS) plots are measured and displayed in Figure 5c, in which the smaller semicircle diameter of FePc‐{PW 12 }@NT based ZAB represents a lower charge transfer resistance [21] . The fast mass transport and accelerated reaction kinetics of FePc‐{PW 12 }@NT cathode play a crucial role for the superior electrochemical performance of the assembled ZAB.…”

Section: Resultsmentioning

confidence: 99%

Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Zhu,

Ding,

Zhang

et al. 2023

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Iron phthalocyanine (FePc) with unique FeN4 site has attracted increasing interests as a promising non‐precious catalyst. However, the plane symmetric structure endows FePc with undesired catalytic performance toward the oxygen reduction reaction (ORR). Here, we report a novel one‐dimensional heterostructured ORR catalyst by coupling FePc at polyoxometalate‐encapsulated carbon nanotubes (FePc‐{PW12}@NTs) using host‐guest chemistry. The encapsulation of polyoxometalates can induce a local tensile strain of single‐walled NTs to strengthen the interactions with FePc. Both the strain and curvature effects of {PW12}@NT scaffold tune the geometric structure and electronic localization of FeN4 centers to enhance the ORR catalytic performance. As expected, such a heterostructured FePc‐{PW12}@NT electrocatalyst exhibits prominent durability, methanol tolerance, and ORR activity with a high half‐wave potential of 0.90 V and a low Tafel slope of 30.9 mV dec−1 in alkaline medium. Besides, the assembled zinc‐air battery demonstrates an ultrahigh power density of 280 mW cm−2, excellent charge/discharge ability and long‐term stability over 500 h, outperforming that of the commercial Pt/C+IrO2 cathode. This study offers a new strategy to design novel heterostructured catalysts and opens a new avenue to regulate the electrocatalytic performance of phthalocyanine molecules.

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“…The electrochemical impedance spectroscopy (EIS) plots are measured and displayed in Figure 5c, in which the smaller semicircle diameter of FePc-{PW 12 }@NT based ZAB represents a lower charge transfer resistance. [21] The fast mass transport and accelerated reaction kinetics of FePc-{PW 12 }@NT cathode play a crucial role for the superior electrochemical performance of the assembled ZAB.…”

Section: Performance Of Zinc-air Batteriesmentioning

confidence: 99%

Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Zhu,

Ding,

Zhang

et al. 2023

Angewandte Chemie

0

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Iron phthalocyanine (FePc) with unique FeN4 site has attracted increasing interests as a promising non‐precious catalyst. However, the plane symmetric structure endows FePc with undesired catalytic performance toward the oxygen reduction reaction (ORR). Here, we report a novel one‐dimensional heterostructured ORR catalyst by coupling FePc at polyoxometalate‐encapsulated carbon nanotubes (FePc‐{PW12}@NTs) using host‐guest chemistry. The encapsulation of polyoxometalates can induce a local tensile strain of single‐walled NTs to strengthen the interactions with FePc. Both the strain and curvature effects of {PW12}@NT scaffold tune the geometric structure and electronic localization of FeN4 centers to enhance the ORR catalytic performance. As expected, such a heterostructured FePc‐{PW12}@NT electrocatalyst exhibits prominent durability, methanol tolerance, and ORR activity with a high half‐wave potential of 0.90 V and a low Tafel slope of 30.9 mV dec−1 in alkaline medium. Besides, the assembled zinc‐air battery demonstrates an ultrahigh power density of 280 mW cm−2, excellent charge/discharge ability and long‐term stability over 500 h, outperforming that of the commercial Pt/C+IrO2 cathode. This study offers a new strategy to design novel heterostructured catalysts and opens a new avenue to regulate the electrocatalytic performance of phthalocyanine molecules.

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“…Equivalent circuit fitting was carried out to gain quantitative data on the performance of these catalysts. To fit a spectrum with an inductive loop with no mass transport limitations, typically, an equivalent circuit, as shown in Figure 13, is used [99]. In this circuit, Rs is the solution resistance, CPEdl is a constant phase element that accounts for the double layer capacitance of an inhomogeneous surface; Rp is the resistance of the Faradaic process, here approximated as the charge transfer resistance; and L and R0 account for the low-frequency inductance.…”

Section: Eis Measurementsmentioning

confidence: 99%

“…CPE values were recalculated into capacitance by Equation ( 13) [99], and the results are shown in Table 5. Another feature of the spectra is the emerging low-frequency inductive loops, particularly apparent for the Co 3 O 4 /gCN sample.…”

Section: Eis Measurementsmentioning

confidence: 99%

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Investigation of Hydrogen and Oxygen Evolution on Cobalt-Nanoparticles-Supported Graphitic Carbon Nitride

Zabielaite,

Balciunaite,

Upskuviene

et al. 2023

Materials

7

0

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This study focuses on fabricating cobalt particles deposited on graphitic carbon nitride (Co/gCN) using annealing, microwave-assisted and hydrothermal syntheses, and their employment in hydrogen and oxygen evolution (HER and OER) reactions. Composition, surface morphology, and structure were examined using inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The performance of Co-modified gCN composites for the HER and OER were investigated in an alkaline media (1 M KOH). Compared to the metal-free gCN, the modification of gCN with Co enhances the electrocatalytic activity towards the HER and OER. Additionally, thermal annealing of both Co(NO3)2 and melamine at 520 °C for 4 h results in the preparation of an effective bifunctional Co3O4/gCN catalyst for the HER with the lower Eonset of −0.24 V, a small overpotential of −294.1 mV at 10 mA cm−2, and a low Tafel slope of −29.6 mV dec−1 in a 1.0 M KOH solution and for the OER with the onset overpotential of 286.2 mV and overpotential of 422.3 mV to achieve a current density of 10 mA cm−2 with the Tafel slope of 72.8 mV dec−1.

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Low-frequency inductive features in the electrochemical impedance spectra of mass-transport limited redox reactions

Abstract: The low-frequency (lf) inductive features in the impedance spectra of electron-transfer reactions at the electrode-electrolyte interface in acidic and alkaline media are investigated. The trend in the lf equivalent circuit...

Cited by 5 publications

References 54 publications

Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Biaxially‐Strained Phthalocyanine at Polyoxometalate@Carbon Nanotube Heterostructure Boosts Oxygen Reduction Catalysis

Investigation of Hydrogen and Oxygen Evolution on Cobalt-Nanoparticles-Supported Graphitic Carbon Nitride

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