Toward Totally Defined Nanocatalysis: Deep Learning Reveals the Extraordinary Activity of Single Pd/C Particles

TLDR

Heterogeneous nanocatalysis is poorly defined because supported catalysts are heterogeneous, morphologically diverse, and nanoscale, making active metal nanoparticles hard to characterize relative to bulk. The study introduces the Totally Defined Catalysis concept and investigates individual Pd/C particles to overcome characterization challenges. The authors used nanomanipulation in a field‑emission scanning electron microscope coupled with neural‑network analysis of individual Pd/C particles. The approach enabled full characterization of single Pd/C particles and revealed an unprecedented turnover number of 10⁹ for individual palladium on a nanoglobular carbon particle.

Abstract

Homogeneous catalysis is typically considered "well-defined" from the standpoint of catalyst structure unambiguity. In contrast, heterogeneous nanocatalysis often falls into the realm of "poorly defined" systems. Supported catalysts are difficult to characterize due to their heterogeneity, variety of morphologies, and large size at the nanoscale. Furthermore, an assortment of active metal nanoparticles examined on the support are negligible compared to those in the bulk catalyst used. To solve these challenges, we studied individual particles of the supported catalyst. We made a significant step forward to fully characterize individual catalyst particles. Combining a nanomanipulation technique inside a field-emission scanning electron microscope with neural network analysis of selected individual particles unexpectedly revealed important aspects of activity for widespread and commercially important Pd/C catalysts. The proposed approach unleashed an unprecedented turnover number of 109 attributed to individual palladium on a nanoglobular carbon particle. Offered in the present study is the Totally Defined Catalysis concept that has tremendous potential for the mechanistic research and development of high-performance catalysts.