The Symmetry Principle in Catalysis: A Viewpoint of the Pseudo-Jahn–Teller Effect

Abstract A symmetry principle for understanding key elementary reaction steps in catalytic reactions is proposed in this study by employing the pseudo-Jahn–Teller effect (PJTE) vibronic coupling theory. The reactivity of elementary reaction steps can be correlated with fractional charge transfer between the catalyst and reactant, which promotes PJTE instability and the symmetry breaking of the adsorbed molecule. Beyond the commonly used adsorption energy, the degree of symmetry deformation of the reactant can serve as an intuitive and important indicator for evaluating the elementary reaction characteristics. Using the adsorption-induced structural activation of reactants in representative elementary steps of the carbon dioxide reduction reaction (CO2RR) and nitrate reduction reaction (NO3RR) as examples, combined with experimental and theoretical evidence, we reveal the intrinsic relationship among fractional charge transfer, reactant distortion, and elementary reaction thermodynamics and activation barriers. This work provides a new physical picture for understanding reactant reactivity and developing new activity descriptors in catalysis.