Ab-initio and comparative analysis of single-atom metal–nitrogen–carbon systems for CO reduction

Sze-Chun Tsang

Research output: Book/ReportPh.D. thesis

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Abstract

Metal–nitrogen–carbon (MNC) systems are seeing an explosion of research interest in recent years for their potential role in diverse energetically- and environmentally-relevant catalytic applications, for example the electrochemical CO2 reduction reaction (CO2RR). Their varied morphologies promise high tunability towards specific reactions, and their compositions represent a way-out from the commonplace use of precious metals in thermo-and electro-catalysis. Naturally, the catalytic activities of these systems are dictated by their interactions with the reactive species and the environment, which are underpinned by their structural and electronic properties.
In this thesis, the current state of the ongoing collaborative work on MNCs in which I have taken part is first summarized. Then, in view of the mixed experimental and theoretical results, I set out to further our understanding of the aforementioned fundamental properties from an ab-initio approach. This is done by the comparative characterization of the electronic structures of both molecular and extended MNCs – specifically, metal–cyclic-tetrapyrrole complexes and graphene-embedded MNC centers; such comparative analysis is then extended to the adsorption energetics on these sites. Attempts are made to construct and identify consistent trends across the various motifs, whilst “traditional” electronic-structure descriptors are illustrated to be insufficient in describing the adsorption energetics. This complexity of chemisorption on MNCs, which sets them apart from transition-metal catalysts, is summarized and discussed. The knowledge compiled and generated in the thesis is envisioned to facilitate the future search and engineering of these materials as catalysts for CO2RR and adjacent reactions. 
Original languageEnglish
PublisherDepartment of Physics, Technical University of Denmark
Number of pages206
Publication statusPublished - 2023

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