(676a) Impact of Pt Nuclearity on CO2 Reduction and Aldol Condensation Reactions | AIChE

(676a) Impact of Pt Nuclearity on CO2 Reduction and Aldol Condensation Reactions


Shi, H. - Presenter, University of Calgary
Murali, S., Pacific Northwest National Laboratory
Lin, F., Pacific Northwest National Laboratory
Lu, Y., Lawrence Berkeley National Laboratory
Zhu, Y., Pacific Northwest National Laboratory
Chen, L., Pacific Northwest National Laboratory
Fulton, J. L., Pacific Northwest National Laboratory
Kovarik, L., Pacific Northwest National Laboratory
Bowden, M., Pacific Northwest National Laboratory
Lercher, J., Pacific Northwest National Laboratory
Gutiérrez-Tinoco, O., Pacific Northwest National Laboratory
Wang, Y., Pacific Northwest National Laboratory
Today, significantly enhanced activity and/or selectivity have been reported on single-atom catalysts (SACs) that surpass those of nanoparticles for heterogeneous reactions. There is considerable evidence that the outstanding performance of SACs arises from a drastic modification of the electronic environment on the catalyst surface to bring in the new chemistry. To understand the structure-function relationships of metal oxide-supported Pt catalysts, especially to study the electronic feature and catalytic performance of sub-nanometer-sized Pt sites that have small atom numbers, we adjusted the geometry of Pt supported on Fe3O4 changing from single-atoms to rafts to nanoparticles gradually. The functionality and stability of the above-mentioned Pt geometries are tested on two different reactions: the reduction of CO2 and the aldol condensation of acetone. Reactivities of CO2 reduction and acetone aldol condensation were found to follow different trends in the presented structures. In the reaction of CO2 reduction, the raft catalysts demonstrate the same turn-over-frequency (TOF) but significantly improved stability compared to the single atoms. In addition, the nuclearity of the Pt structures is found to be crucial in determining the phase transition and involvement of the Fe3O4 support in the CO2 reduction. On the other side, the raft and nanoparticle catalysts cannot compete with the single atoms regarding the activity in the aldol-condensation reaction. A series of prevailing characterizations were performed on the synthesized Pt structures, and the results underline our hypothesis that doping Pt single atoms to the surface of Fe3O4 creates stronger Ptδ+-O2- pairs facilitating the acetone adsorption and α-H abstraction steps, which eventually results in the remarkable high activity of the Pt SAC in the self-coupling of acetone.