(647f) Theoretical Insights on Boron Nitride-Supported Sub-Nanometer Pd6 Clusters for Formic Acid Decomposition: The Effect of Defects

Authors: 
Schimmenti, R., University of Wisconsin-Madison
Mavrikakis, M., University of Wisconsin-Madison
Sub-nanometer metallic clusters were recently demonstrated to be promising, highly selective catalysts for various chemical processes, such as propylene epoxidation.1,2 The presence of extremely low-coordinated metal sites as well as effects arising from the interaction with supports are among the reasons of their peculiar catalytic properties.

By means of a periodic, self-consistent planewave DFT approach, we evaluate the potential use of a hexagonal boron nitride (h-BN) supported sub-nanometer Pd6 cluster as catalysts for the selective decomposition of formic acid (FA) to hydrogen. The competition between formate (HCOO) and carboxyl (COOH) decomposition pathways was studied on different sites. The effect of support defects (e.g., B and N monovacancies) was explicitly considered.

DFT calculations suggest that Pd­6 could be a promising candidate for the selective production of H2 from FA. Indeed, the reaction mainly follows the HCOO route, while formation of COOH, a well-known CO precursor, is energetically not favored, which is in contrast to what we expect for large Pd nanoparticles.3,4

However, we demonstrated that the reaction energetics can be controlled by the interplay of various factors, such as electronic charge transfer and cluster reconstructions, which appear when defects are present on the support. The rationalization of these effects, which is possible through the use of electronic structure calculations, is essential to capture and then predict catalytic properties at the sub-nano regime.

References

  1. Vajda S., White G., ACS Catal. 5, 12, 7152–7176 (2015).
  2. Lei Y., Mehmood F., Lee S., Greeley J., Lee B., Seifert S., Winans R. E., Elam J. W., Meyer R. J., Refdern P. C., Teschner D., Schlögl R., Pellin J. M., Curtiss L. A., Vajda S., Science 328, 5975, 224–228 (2010)
  3. Schimmenti R., Cortese R., Duca D., Mavrikakis M., ChemCatChem 9, 9, 1610–1620 (2017).
  4. Herron J. A., Scaranto J., Ferrin P., Li S., Mavrikakis M., ACS Catal., 4, 12, 4434–4445 (2014)