Method could quicken the characterization of single-nanoparticle catalysts

Nanoparticles can potentially be used as industrial catalysts, but characterizing the exact catalytic behavior of a nanoparticle is difficult since no two nanoparticles are the same. The catalytic activity of the same type of nanoparticle, for example, can vary by several orders of magnitude due to different morphologies and reactive sites. Gao et al. reported a high-throughput method to measure the catalytic activities of multiple, single nanoparticles in realistic working conditions.

With a microwell-based method, the authors determined, in operando, the catalytic activities of single nanoparticles when placed in conditions with a high reactant concentration and high turnover frequency. The activities, as expected, differed for each single nanoparticle. Furthermore, utilizing this method, two types of catalytic behaviors were deciphered for cadmium sulfide nanoparticles: rapid decline in activity for most nanoparticles and an initially increased activity prior to deactivation for a minor population of catalysts. This finding was not easily observable in traditional bulk level measurements.

“Increased concentration of reactants might lead to a significant diffusion of reactants and products among different individuals, i.e., cross talking, which may hamper the measurement of intrinsic activities of single entities,” author Wei Wang said. “By sealing individual nanoparticles into separated microwells, the cross talking among individuals in the case of high concentration of reactants was eliminated.”

Wang added the method was inspired by microwell arrays used to characterize single-molecule enzyme catalysts.

In addition to measuring catalytic activities, the authors hope to understand the relationship between nanoparticle structure and catalytic activities with both in situ and ex situ techniques.

Source: “A microwell array-based approach for studying single nanoparticle catalysis with high turnover frequency,” by Jia Gao, Hua Su, and Wei Wang, Journal of Chemical Physics (2021). The article can be accessed at https://doi.org/10.1063/5.0058402 .

This paper is part of the Chemical Imaging Collection, learn more here .