November 21, 2014

Higly selective catalysts for CO2 electroreduction

Edge sites are highly selective.

The ability to convert CO2 to chemicals may enable renewable chemicals and fuels to be produced without the use of fossil fuels or biomass. In a previous publication, we used a combination of electronic structure calculations and precisely synthesized nanoparticles in order to identify that edge sites on Au electrocatalysts are highly selective for CO production from CO2, while the corner sites are highly active for the competitiv H2 evolution reaction.

With this knowledge of the active site, we were able to predict that changing the particle geometry from spherical to cylindrical would result in a highly-selective catalyst. This is due to maximizing the active edge sites, as shown in orange on the figure. In a collaboration with Shouheng Sun's group, we synthesized such particles, which are shown in a transmission electron micrograph in the background of the figure. These 'gold nanowires' have diameters of 2 nm and a lengths of up to 500 nm.

We used these particles in an electrochemical cell to measure their activity for CO2 reduction. The results are compared with those of the previous best nanoparticles in the figure. As can be seen, the Faradaic efficiency (FE) is drastically improved at low overpotentials as compared to the previous best nanoparticles. The resulting catalyst has among the highest-reported mass activity and selectivity of any heterogenous CO evolution catalyst.

Read more in JACS.