New catalyst concepts for the electrochemical conversion of CO2


Event details

Date 30.11.2017
Hour 10:3011:30
Speaker Dr. Peter Broekmann, Department of Chemistry and Biochemistry, University of Bern, Switzerland
Category Conferences - Seminars
ChE-605 - Highlights in Energy Research seminar series

The electrochemical conversion of CO2 into products of higher value (e.g. CO, formate, ethanol, n-propanol) can be considered as a seminal approach that has the technological potential of contributing to a future closing of the anthropogenic carbon cycle. Such CO2 electroreduction process (denoted as CO2RR) offers not only the unique chance to reduce the amount of environmentally harmful CO2, it provides in addition means of storing intermittently produced excesses of electricity originating from renewables like wind, solar and hydro sources.

Major challenges that currently prevent such electrochemical CO2 conversion technology from being implemented into industrial applications are related to the enormous overpotentials needed for CO2 activation, thus typically resulting into a poor energy efficiency of the entire full cell-level process. Another key challenge of the process development remains the product selectivity. Among the vast number of materials screened so far, it is Cu which deserves particular attention since it is the only catalyst which is capable to convert CO2 into hydrocarbons and alcohols in considerable amounts. Crucial for the performance of the Cu catalysts is their pre-treatment, e.g. by thermal annealing, exposure to oxygen plasma, electrodeposition, and electrodeposition. This pretreatment provides not only means of forming catalytically active sites and surface textures but creates in addition particular catalyst morphologies on various length scales that are needed to guide the CO2RR into the desired direction. 

An additive-assisted metal foam electrodeposition can be considered as a promising approach towards design and production of novel high-surface area CO2RR catalysts.[1-2] For selected examples, it will be demonstrated that oxide-derived Cu foam catalysts can reach Faradaic efficiencies of up to 25% for the production of highly valuable C2 and C3 alcohols. Identical location (IL) SEM/TEM investigations in combination with operando Raman and EXAFS/XANES measurements clearly prove that the actually active catalyst forms only under reactive conditions during an ongoing CO2RR. Particularly important for the long-term stability of the Cu catalysts is the complete suppression of the C1 pathway of methane production.          
[1]  A. Dutta, M. Rahaman, N. C. Luedi, M. Mohos, P. Broekmann, ACS Catal. 6 (2016) 3804-3814
[2]  A. Dutta, M. Rahaman, M. Mohos, A. Zanetti, P. Broekmann, ACS Catal. 7 (2017) 5431–5437