(66f) Exploring Non-Equilibrium Chemical Subspace in Electrocatalysis

Many electrocatalysis undergo significant surface changes in the reaction conditions. Knowledge of its correct atomic structure is the prerequisite of any reactivity study. The recent development of grand canonical optimization techniques enables efficient exploration of the off-stoichiometric chemical space to construct grand canonical ensemble representations and surface phase diagrams. However, there have been emerging concerns that many electrochemical systems may suffer kinetic trapping in the metastable regime, and even more, evolves and operates in non-equilibrium in the catalytic timescale. They do not follow the ab initio thermodynamics, and regular global optimization techniques (going after the regions near the global minimum) would under-sample many metastable regimes.

Here we showcase the recent developments in biasing and constraining the global optimizers into the catalysis-relevant regions corresponding to kinetic trapping. This technique is applied to better understand the off-equilibrium structures of Cu in CO2/CO reduction reaction, surface of borated Cu in CO2/CO reduction reaction, and metal boride surface in hydrogen evolution reaction. We demonstrate the importance of biased sampling in extensively exploring the off-equilibrium chemical space, and the rich insights it provides. I'd also highlight a case where the treatment saves us from the danger of "getting the right answer for the wrong reason".

This collection of work is highly relevant to the emerging interests in exploring non-equilibrium states in both catalysis and material science.