Issue 24, 2017

A biomimetic photoelectrocatalyst of Co–porphyrin combined with a g-C3N4 nanosheet based on π–π supramolecular interaction for high-efficiency CO2 reduction in water medium

Abstract

Aiming at high-efficiency biomimetic CO2 photoelectrochemical conversion, a photoelectrocatalyst with excellent CO2 catalytic activity was designed and prepared by immobilizing CoTPP (cobalt meso-tetraphenylporphyrin) onto g-C3N4 conveniently via self-assembly based on π–π supramolecular interaction. The quasi 3-D structure of CoTPP showed a suitable hole with a size of 3.8 Å × 9.6 Å which favoured CO2 adsorption. The pores formed by the π–π stacking of CoTPP and g-C3N4 also provided additional space for CO2 adsorption, which was confirmed by the appearance of a desorption peak at 250 °C in the temperature programmed desorption measurement for CoTPP/g-C3N4. As a normal efficient homogeneous catalyst in organic media, CoTPP commendably maintained outstanding CO2 photoelectrocatalytic activity in heterogeneous aqueous solution, even at a low overpotential of −0.6 V (vs. normal hydrogen electrode, NHE). Under 8 h PEC CO2 reduction, formic acid generation on CoTPP/g-C3N4 reached 154.4 μmol with a TON of 137 and high selectivity of nearly 100% in liquid products. The formation of CoTPP–COO and CoTPP–COOH intermediates by the Co(II) active site and CO2 was investigated by in situ UV-vis and Raman spectra. Moreover, an isotopic labelling experiment indicated that water supplied abundant protons for the production of formic acid.

Graphical abstract: A biomimetic photoelectrocatalyst of Co–porphyrin combined with a g-C3N4 nanosheet based on π–π supramolecular interaction for high-efficiency CO2 reduction in water medium

Supplementary files

Article information

Article type
Paper
Submitted
31 aug 2017
Accepted
03 nov 2017
First published
06 nov 2017

Green Chem., 2017,19, 5900-5910

A biomimetic photoelectrocatalyst of Co–porphyrin combined with a g-C3N4 nanosheet based on π–π supramolecular interaction for high-efficiency CO2 reduction in water medium

J. Liu, H. Shi, Q. Shen, C. Guo and G. Zhao, Green Chem., 2017, 19, 5900 DOI: 10.1039/C7GC02657A

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