(12d) The Influence of Plasma-Induced Surface Charging on Single-Atom Catalysis for CO2 Reduction

Low-temperature plasma (LTP) catalysis is a growing field of research, reporting various synergistic effects for increased activity, yield, or selectivity compared to conventional thermocatalytic approaches. LTP can activate stable molecules such as CO₂ via interactions with high-energy electrons. Still, the many effects that LTP has on surface-catalyzed reactions are multi-faceted and poorly understood at an atomistic level. It would help to understand the effects of plasma on a catalyst surface by studying each in isolation. For instance, the LTP contains many charged particles and excited electrons, and this causes a negative charge to accumulate on the exposed surface. In this work, we study the effect of surface charging due to LTP in isolation for the CO₂ reduction reaction.

Using density functional theory modeling, we study single-atom catalyst systems across the periodic table to understand the importance of surface charging on CO₂ activation. We analyze six different metals (Co, Ni, Cu, Rh, Pd, and Ag) as dispersed metal ions. These metals are dispersed on three different supports (CeO₂, TiO₂, Al₂O₃), each with varying levels of reducibility.

Our modeling approach is adapted from recent literature¹ and applied to observe the plasma’s effect on catalytic activity. We add a negative charge to the single metal atom on the catalyst surface and a counterion (H⁺) to the vacuum layer to maintain overall neutrality. This simulates an electric field that can be tuned by varying the distance between point charges. We predict CO₂ binding energy and reaction barrier trends to characterize each system’s catalytic activity. Our results show that the adsorption and reaction trends for CO₂ reduction differ between plasma and thermal catalysis, implying that insights from one field may not necessarily apply to the other.

1. K. M. Bal, S. Huygh, A. Bogaerts and E. C. Neyts, Plasma Sources Sci. Technol., 2018, 27, 024001.