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O: Fachverband Oberflächenphysik

O 111: Heterogeneous Catalysis II

O 111.3: Vortrag

Freitag, 22. März 2024, 11:00–11:15, TC 006

Systematic evaluation of trends in CO2 reduction on metal–nitrogen–carbon systems from first principles — •Sze-Chun Tsang, Sihang Liu, and Georg Kastlunger — Catalysis Theory Center, Technical Univ. of Denmark, 2800 Kgs. Lyngby, Denmark

The electrochemical CO2 reduction reaction (e-CO2RR) can be a crucial aspect of sustainability. Metal–nitrogen–carbon (MNC) single-atom catalysts (SACs) hold promises towards electroreduction, besting transition-metal (TM) surface catalysts in suppressing side reactions and unlocking new energetic degrees-of-freedom. However, adsorbates on MNCs are often poorly modeled; and the oft-assumed and -used analogy between graphene-based (G-) and molecular MNCs has yet to be examined.

Using density-functional theory, we compare the adsorption energetics relevant to the CO2RR on G-MNCs and molecular MNCs. We will show energetic trends to be largely metal-dependent and consistent across SAC geometries. We also demonstrate that higher-level theories like the exact-exchange functional are crucial towards capturing said energetics. Further, we examine the pairwise correlation, or the lack thereof, between reaction-intermediate formation energies on 3d-TM-based MNCs. Finally, we discuss several caveats: (1) the sampling of spin states and its energetic ramifications; and (2) the tendencies for protons to potentially destabilize the active site. These results emphasize the importance of and highlight the difficulties in correctly describing MNC systems, illuminating key theoretical insights into this distinguished class of catalysts.

Keywords: MNC; DFT; CO2RR; Electrocatalysis; 2D materials