Modified Carbon Nanotubes: Surface Properties and Activity in Oxygen Reduction Reaction
In order to develop highly efficient and stable catalysts for oxygen reduction reaction (ORR) that do not contain precious metals, it is necessary to modify carbon nanotubes (CNT) and define the effect of the modification on their activity in the ORR. In this work, the modification of CNTs included...
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| Autores principales: | , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/c3daff0787744a39af5230ab132617bb |
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| Sumario: | In order to develop highly efficient and stable catalysts for oxygen reduction reaction (ORR) that do not contain precious metals, it is necessary to modify carbon nanotubes (CNT) and define the effect of the modification on their activity in the ORR. In this work, the modification of CNTs included functionalization by treatment in NaOH or HNO<sub>3</sub> (soft and hard conditions, respectively) and subsequent doping with nitrogen (melamine was used as a precursor). The main parameters that determine the efficiency of modified CNT in ORR are composition and surface area (XPS, BET), hydrophilic–hydrophobic surface properties (method of standard contact porosimetry (MSP)) and zeta potential (dynamic light scattering method). The activity of CNT in ORR was assessed following half-wave potential, current density within kinetic potential range and the electrochemically active surface area (S<sub>EAS</sub>). The obtained results show that the modification of CNT with oxygen-containing groups leads to an increase in hydrophilicity and, consequently, S<sub>EAS</sub>, as well as the total (overall) current. Subsequent doping with nitrogen ensures further increase in S<sub>EAS</sub>, higher zeta potential and specific activity in ORR, reflected in the shift of the half-wave potential by 150 mV for CNT<sub>NaOH-N</sub> and 110 mV for CNT<sub>HNO3-N</sub> relative to CNT<sub>NaOH</sub> and CNT<sub>HNO3</sub>, respectively. Moreover, the introduction of N into the structure of CNT<sub>HNO3</sub> increases their corrosion stability. |
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