Electrocatalysis Using Cobalt Porphyrin Covalently Linked with Multi‐Walled Carbon Nanotubes: Hydrazine Sensing and Hydrazine‐Assisted Green Hydrogen Synthesis

Abstract

AbstractAcid‐treated multi‐walled carbon nanotube (MWCNT) covalently functionalized with cobalt triphenothiazine porphyrin (CoTriPTZ‐OH) A3B type porphyrin, containing three phenothiazine moieties (represented as MWCNT‐CoTriPTZ) is synthesized and characterized by various spectroscopic and microscopic techniques. The nanoconjugate, MWCNT‐CoTriPTZ, exhibits a pair of distinct redox peaks due to the Co2+/Co3+ redox process in 0.1 M pH 7.0 phosphate buffer. Further, it electrocatalytically oxidizes hydrazine at a low overpotential with a high current. This property is advantageously utilized for the sensitive determination of hydrazine. The developed electrochemical sensor exhibits high sensitivity (0.99 µAµM−1cm−2), a low limit of detection (4.5 ppb), and a broad linear calibration range (0.1 µM to 3.0 mM) for the determination of hydrazine. Further, MWCNT‐CoTriPTZ is exploited for hydrazine‐assisted green hydrogen synthesis. The high efficiency of hydrazine oxidation is confirmed by the low onset potential (0.45 V (vs RHE)) and 0.60 V (vs RHE) at the current density of 10 mA.cm−2. MWCNT‐CoTriPTZ displays a high current density (77.29 mA.cm−2) at 1.45 V (vs RHE).