Covalent ligation of Co molecular catalyst to carbon cloth for efficient electroreduction of CO2 in water

Aleksei N. Marianov, Yijiao Jiang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)

Abstract

Electrochemical reduction of CO2 to CO in water catalysed by porphyrins is a viable way to environmentally friendly CO2 valorisation, while efficient catalyst immobilization on the electrode surface is one of the key challenges to answer. Herein we present a concept of "molecular wire" i.e. connection of the catalyst to electrode via a conductive covalent linker. To covalently immobilize Co porphyrin core onto carbon cloth we employed reduction of corresponding diazonium salt. "Wiring' via resulting phenylene group had profound effect on electrocatalytic performance. Formation of CO in neutral aqueous electrolyte at –1.05 V vs NHE (η = 500 mV) occurs with TOF of 8.3 s−1 while noncovalent counterpart has TOF of 4.5 s−1 only. Compared to the noncovalent mode, covalent ligation leads to 2.4 times higher surface density of electrochemically active species and maximum FE (CO) is achieved at 50 mV less negative potential. The catalyst accumulated 3.9‧105 TON in 24 h long electrolysis surpassing performance of drop-cast analogue by a factor of 3 and showed FE (CO) of up to 81%. Notably, the TON and TOF values achieved in our study are one of the highest reported to date surpassing those measured for Fe hydroxyporphyrins and Co porphyrin-based covalent organic frameworks. Electrokinetic analysis demonstrated that the electron transfer from electrode onto porphyrin moiety plays an important role in overall reaction kinetics and conductive link with the support is a key element of heterogeneous catalyst design.

Original languageEnglish
Pages (from-to)881-888
Number of pages8
JournalApplied Catalysis B: Environmental
Volume244
DOIs
Publication statusPublished - 5 May 2019

Keywords

  • CO₂ electroreduction
  • Electrochemistry
  • Covalent immobilization
  • Cobalt porphyrin

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