Developing immobilized molecular complexes, which demonstrate high product efficiencies at low overpotential in the electrochemical reduction of CO2 in aqueous media, is essential for the practical production of reduction products. In this work, a simple and facile self-assembly method is demonstrated by electrostatic interaction and π–π stacking for the fabrication of a porphyrin/graphene framework (FePGF) composed of Fe(III) tetraphenyltrimethylammonium porphyrin and reduced liquid crystalline graphene oxide that can be utilized for the electrocatalytic reduction of CO2 to CO on a glassy carbon electrode in aqueous electrolyte. The FePGF results in an outstanding robust catalytic performance for the production of CO with 97.0% faradaic efficiency at an overpotential of 480 mV and superior long-term stability relative to other heterogeneous molecular complexes of over 24 h (cathodic energy efficiency: 58.1%). In addition, a high surface area carbon fiber paper is used as a substrate for FePGF catalyst, resulting in enhanced current density of 1.68 mA cm−2 with 98.7% CO faradaic efficiency at an overpotential of 430 mV for 10 h, corresponding to a turnover frequency of 2.9 s−1 and 104 400 turnover number. Furthermore, FePGF/CFP has one of the highest cathodic energy efficiencies (60.9%) reported for immobilized metal complex catalysts.
Bibliographical noteFunding Information:
This work was supported by the ARC Centre of Excellence Scheme (Project No. CE 140100012). J.C. also thanks the University of Wollongong (UOW) for a University Postgraduate Award. D.R.M. is grateful for support from the Australian Research Council for his Australian Laureate Fellowship. The authors thank the Materials Node of the Australian National Fabrication Facility (ANFF) and the UOW Electron Microscopy Centre for their facilities and research support.
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All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)