Single-atom Catalysis

by Ning YAN
Single-atom Catalysis

Every Rh metal atom is a working horse!

Atomically dispersed Rh catalysts supported on phosphotungstic acid (PTA) with Rh loading up to 0.9 wt % were prepared through a self-assembly method. Rh stays exclusively as single atom species coordinated to six oxygen atoms, plausibly located at the 4-fold hollow site on one phosphotungstic acid (PTA) molecule together with a chemically adsorbed O2 molecule. The catalyst is active in CO oxidation affording turnover frequencies between 0.2 and 1.7 s−1 from 165 to 195 °C, with an apparent activation energy of 127 kJ/mol. The catalyst is highly stable, well maintaining the Keggin structure of PTA as well as the single-atom identity of Rh after three catalytic cycles. CO activation is mainly achieved on Rh via the formation of dicarbonyl species, while oxygen activation and transfer mainly occur through PTA. The proposed catalytic cycle consists of an alternation of Rh(CO)23+ species and Rh(CO)21+ species on PTA, during which CO transforms into CO2 with oxygen activation being rate-determining.

This work has been published in Ind. Eng. Chem. Res. on March 09, 2017 (doi: 10.1021/acs.iecr.7b00376), as Front Cover. It is also an invited article in themed issue “2017 Class of Influential Researchers”.

Corresponding author(s): Ning, Yan (ning.yan@nus.edu.sg)
Corresponding authors(s) Webpage: http://yan-nus.weebly.com/