Reaction on a Rink: Kondo-Enhanced Heterogeneous Single-atom Catalysis

Abstract

Boosting the efficiency of heterogeneous single-atom catalysts (SACs) by adjusting the microenvironment of the active atom has recently attracted enormous attention. However, attempts to tune the spin-spin interaction between the SAC and its microenvironment have remained rather scarce. Some interesting questions can be raised, among which a fundamental one is: can the surrounding environment influence the local spin state of an SAC, and if so, can such influence be utilized to enhance the catalytic activity? In this work, we explore such a possibility by investigating the thermochemical effect of Kondo screening of a local atomic spin by free electrons in the metal support. Inspired by the exothermicity of the spin-screening interaction, a novel approach to heterogeneous catalysis -- reaction on a rink (ROAR) -- is proposed. In contrast to the conventional notion of thermal catalytic reaction, lowering the temperature of metal support is predicted to result in a reduced reaction barrier. As a proof of concept, CO oxidation catalyzed by the Co@CoPc/Au(111) composite is scrutinized. By combining the density functional theory and a hierarchical equations of motion approach, it predicts that the existing s-d hybridization between the magnetic d orbital of Co adatom and the substrate metallic states in the transition state will lower the free energy barrier and accelerate the reaction rate. Furthermore, if the strength of s-d hybridization is enlarged, a more appreciable speedup will be achieved. This work highlights the potential usefulness of the spin degrees of freedom to heterogeneous single-atom catalysis, and our proposed ROAR approach could open up a new horizon for exploiting the role of atomic spin in chemical reactions.