(582at) Engineering Metal/SnOx Interfaces for Electrochemical CO2 Reduction

With dwindling fossil fuels and rising concern about their impacts on climate, electrochemical reduction of CO₂ has attracted researchers’ attention as it has the potential to utilize the abundant greenhouse gas in the Earth’s atmosphere and store intermittent energy from solar panels and wind turbines in chemical bonds^1,2. A commercially viable catalyst for CO₂ electroreduction should meet the cost-effective requirement while possessing high efficiency and selectivity. Experimental studies showed that tin oxides (SnOx) have the ability to selectively convert CO₂ to formate (HCOO^-), although the reaction mechanism is not clear with respect to the nature of active sites and the process occurs at prohibitively high overpotentials (~1 V) ³.

The goal of this study is to understand the reaction mechanism of CO₂ electroreduction on SnOx and leverage that knowledge to design metal/SnOx composite catalysts with superior activity. In this poster, we will discuss the reaction mechanism of CO₂ reduction on SnOx obtained from first-principles density functional theory calculations, focusing on the competing pathways leading to the production of CO, H₂, and HCOO^-. We found that the outcome of CO₂ electroreduction on SnOx is highly dependent on its surface structure, which can explain a wide range of faradaic efficiencies for formate production on SnOx reported in different studies. By engineering the lattice strain of SnOx, we illustrated that the electrocatalytic reactivity toward formate can be further optimized, while the CO formation pathway is barely affected^4,5.

1. Hori, Y. in Modern Aspects of Electrochemistry (eds. Vayenas, C. G., White, R. E. & Gamboa-Aldeco, M. E.) 89–189 (Springer New York, 2008).

2. Ma, X., Li, Z., Achenie, L. E. K. & Xin, H. Machine-Learning-Augmented Chemisorption Model for CO2 Electroreduction Catalyst Screening. J. Phys. Chem. Lett. 6, 3528–3533 (2015).

3. Chen, Y. & Kanan, M. W. Tin Oxide Dependence of the CO2 Reduction Efficiency on Tin Electrodes and Enhanced Activity for Tin/Tin Oxide Thin-Film Catalysts. J. Am. Chem. Soc. 134, 1986–1989 (2012).

4. Wang, S., Wang, J. & Xin, H. Insights into electrochemical CO2 reduction on tin oxides from first-principles calculations. Green Energy Environ. doi:10.1016/j.gee.2017.02.005

5. Luc, W. et al. Ag–Sn Bimetallic Catalyst with a Core–Shell Structure for CO2 Reduction. J. Am. Chem. Soc. 139, 1885–1893 (2017).