Computational study of metal-nitrogen doped carbon catalysts in CO2 electroreduction

Abstract

The escalating threat of global warming and energy scarcity is driving the search for sustainable and efficient means to convert CO2 into value-added chemicals and fuels. This study presents an in-depth computational examination of the catalytic performance of metal-nitrogen doped carbon catalysts in the CO2 electroreduction reaction. In Chapter 1, the thesis provides an overview of electrochemical CO2 reduction, the role of M-N-C catalysts, and computational approaches for studying electrochemical reactions. The chapter sets the stage for the rest of the research by elaborating on the challenges and opportunities in this field, thereby demonstrating the potential of M-N-C catalysts in CO2 electroreduction. Chapter 2 focuses on a density functional theory (DFT)-based screening of M-N-C electrocatalysts for CO2 reduction to CO. The chapter demonstrates a systematic process to identify Fe-N-C, Co-N-C, and Ni-N-C electrocatalysts as promising candidates from 23 types of M-N-C nanomaterials. Furthermore, it reveals the potential of DFT-driven descriptors to predict the catalytic activity and selectivity of the candidates. This part of the study provides significant insights into the rational design of heterogeneous electrocatalysts for energy conversion. Chapter 3 extends the research to the construction of dual-atom Fe pair sites. It demonstrates the impressive CO2-to-CO electroreduction performance achieved through the unique dual Fe2-N6 configuration. This chapter also highlights the underlying mechanism responsible for the observed conversion, attributing it to the synergistic effects on Fe2 site formation. The discoveries in this chapter pave the way for the optimized design of dual atomic catalysts (DACs) for targeted heterogeneous catalysis. Finally, Chapter 4 provides a thorough computational study of the electrochemical CO2 reduction to CH4 on M-N-C catalysts. The study reveals the complexity of the CO2 reduction reaction, emphasizing the crucial role of catalyst selection and potential-dependent energetics in the conversion process. It further investigates the potential parasitic reactions during *CO protonation and potential-dependent energy differences in *CO protonation and competitive reactions. This comprehensive analysis contributes to the development of more efficient and selective catalysts for the electrochemical reduction of CO2. In conclusion, this thesis offers a robust computational investigation into the CO2 electroreduction on M-N-C catalysts. It underscores the potential of these catalysts in sustainable energy conversion, providing the foundation for future experimental validation and further theoretical exploration of other potential reaction intermediates and products.