(127f) CO2 Electroreduction on Modified Cu Catalysts: Using Subsurface Dopants to Enhance Catalytic Performance | AIChE

(127f) CO2 Electroreduction on Modified Cu Catalysts: Using Subsurface Dopants to Enhance Catalytic Performance

Authors 

Che, F. - Presenter, University of Toronto
Sargent, E., University of Toronto
Zhou, Y., University of Toronto
Liu, M., University of Toronto
Zou, C., University of Toronto
Liang, Z., University of Toronto
Luna, P. D., University of Toronto
Yuan, H., University of Toronto
Li, J., University of Toronto
Sinton, D., University of Toronto
Wang, Z., Western University
Xie, H., University of Toronto
Li, H., University of Toronto
Chen, P., University of Toronto
Bladt, E., University of Antwerp
Quintero-Bermudez, R., University of Toronto
Sham, T. K., University of Western Ontario
Bals, S., University of Antwerp
Hofkens, J., University of Toronto
Chen, G., Harbin Institute of Technology
The electrochemical reduction of CO2 (CO2RR) over Cu to a single class of target hydrocarbons – ethylene represents one prominent example of intense recent interest – is attracting considerable attention. It provides an avenue to the synthesis of high energy density and high economic value feedstocks and fuels using renewable electricity. However, before CO2RR can be widely applied, at least two significant issues need to be addressed: (1) Previous research has shown that modified copper is especially selective in CO2RR; however, diverse C1 and C2 species are generated simultaneously. It is of interest to enhance the selectivity to a single high-value hydrocarbon product at high activity; (2) High Faradaic efficiencies for C2 products have been achieved by inducing surface Cuδ+ sites in Cu via oxygen species. Since such Cuδ+ sites are expected to be readily reduced to Cu0 under CO2RR, it is of interest to increase the stability of the Cuδ+ sites in Cu.

We took the view that the electronegativity of new dopants could increase Cuδ+ sites and offer a subsurface doping strategy that keeps the Cuδ+ sites stable under the reducing potentials used in CO2RR. In DFT calculations (Figure 1), we found that boron and carbon elements under negative applied potential can be stable at the subsurface of a Cu(111) slab, and that they greatly alter the Cu oxidation state to be positive, and as a consequence enhance the selectivity of ethylene products from CO2RR. Our corresponding experiments also achieve a high Faradaic efficiency for ethylene of ~52% for boron-doped Cu and ~78% for carbon-doped Cu. Importantly, boron-doped and carbon-doped copper showed ~40 h and ~170 h stability for CO2RR to ethylene. This theoretical and experimental combined work indicates a role for subsurface chemistry in enhancing the selectivity and stability of the Cu based CO2RR system.