Dohyung Kim1 Yifan Li1 Peidong Yang1

1, University of California, Berkeley, Berkeley, California, United States

Growing concerns of the economical, societal and environmental impacts of the human age (i.e. Anthropocene) have led to finding innovative carbon management solutions to mitigate its negative effects and to move on to a more sustainable era. As a part of the effort, electrochemically converting carbon dioxide to value-added products has gained significant interest. However, developments in the field have been slow, mainly from the difficulties associated with finding efficient catalysts for multicarbon (C2-C3) formation. Not only it is difficult to selectively form multicarbon products from CO2, but the overpotentials required to enable their formation is significantly high limiting the efficiency. Recently, we discovered a Cu-based electrocatalyst that could selectively reduce CO2 to C2-C3 products at significantly reduced overpotentials, compared to what have been mostly reported so far. This active catalyst was made from using copper nanoparticle ensembles as precursors and inducing their structural transformation during CO2 electrolysis. In-situ structural change led to the formation of cuboidal particles which facilitated the formation of ethylene, ethanol, and n-propanol as the major C2-C3 products. The onset of these products occurred as low as -0.5 volts (vs. RHE, reversible hydrogen electrode) and C2-C3 faradaic efficiency (FE) > 50% was acquired at only -0.75 volts. This catalytic structure also remains active for longer periods demonstrated by stable performance over 10 hours. Investigating the structural evolution in the relevant electrochemical environments has led to identifying unique traits of the process that shed light into the dynamic processes involved for materials in electrochemical conditions. Furthermore, structural characteristics responsible for selective C2-C3 formation have been studied to correlate with electrokinetic studies identifying CO dimerization as a rate determining step for C2 products and a separate pathway for C3.