Energy efficient electrochemical reduction of CO2 to CO using a three-dimensional porphyrin/graphene hydrogel

• Published in: Energy & environmental science 2019-01, Vol.12 (2), p.747-755
• Main Authors: Choi, Jaecheol, Kim, Jeonghun, Wagner, Pawel, Gambhir, Sanjeev, Jalili, Rouhollah, Byun, Seoungwoo, Sayyar, Sepidar, Lee, Yong Min, MacFarlane, Douglas R, Wallace, Gordon G, Officer, David L
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Carbon dioxide; Carbon monoxide; Catalysis; Catalytic activity; Chemical reduction; Coordination compounds; Durability; Electrocatalysts; Electrochemistry; Electrolysis; Energy conversion efficiency; Energy efficiency; Graphene; Hydrogels; Iron; Organic chemistry; State of the art
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c8ee03403f

Although electrochemical CO2 reduction is one of the most promising ways to convert atmospheric CO2 into value-added chemicals, there are still numerous limitations to overcome to achieve highly efficient CO2 conversion performance. Herein, we report for the first time the development and use of a three-dimensional iron porphyrin-based graphene hydrogel (FePGH) as an electrocatalyst for extremely efficient robust CO2 reduction to CO. Electrocatalytic CO2 conversion was performed in aqueous medium with FePGH, which has a highly porous and conductive 3D graphene structure, resulting in high catalytic activity for CO production with ∼96.2% faradaic efficiency at a very low overpotential of 280 mV. Furthermore, FePGH showed considerable catalytic durability maintaining a consistent CO yield (96.4% FE) over 20 h electrolysis at the same overpotential, corresponding to the highest cathodic energy efficiency yet observed of 79.7% compared to other state-of-the-art immobilised metal complex electrocatalysts. This approach to fabricating a 3D graphene-based hydrogel electrocatalyst should provide an exciting new avenue for the development of other kinds of molecular electrocatalysts.