Analyzing the Roles of Copper in Carbon Capture and Sequestration Using Mean Field Density Functional Theory and Scanning Transmission Electron Microscopy
Authors: Pourrahmani Hossein 
Published: December 2024

Exploring the role of Copper (Cu) in carbon capture and sequestration presents a rich area for research, including but not limited to Nanostructure copper materials, Copper-based hybrid materials, Copper-based electrocatalysts, copper in biomimetic systems, Copper-based membranes for gas separation, Copper in carbon mineralization, Copper in photochemical conversion, and copper-based direct air capture technologies that can enhance the capture and conversion. In this regard, efficient methods to characterize the role of Cu in carbon sequestration processes should be developed computationally and experimentally.
Among the computational methods, the mean-field density functional theory (DFT) is capable of calculating the adsorption isotherms of on Cu-containing materials, such as Cu nanoparticles or surfaces. By modeling the existing interactions between molecules and Cu sites using classical force fields or empirical potentials, it is possible to estimate the adsorption capacity, energetics, and equilibrium behavior of Cu-based adsorbents under various temperature and pressure conditions. Additionally, DFT is capable to provide insights into the surface chemistry and reactivity of Cu-based materials during adsorption and catalytic conversion reactions. In this regard, surface defects, step edges, and coordination sites can be elucidated to facilitate the activation, chemisorption, and subsequent reactions. As another application of DFT, the thermodynamic properties and phase equilibria of Cu- systems can be determined particularly in multi-component fluid mixtures where phase behavior, solubility limits, and speciation of Cu complexes in -rich environments can be predicted by modeling the interactions between Cu ions or clusters and molecules. Sorption mechanisms and kinetics of on Cu adsorbents can be modeled by DFT by presenting the diffusion processes, surface interactions, and pore-filling phenomena. Lastly, mean-field DFT can establish structure-property relationships between the atomic-scale structure and macroscopic properties of Cu-based materials in carbon sequestration applications. The result of DFT can be correlated to the experimental results to understand key structural features, surface modifications, or compositional variations that influence the performance of Cu catalysts or sorbents, leading to rational design strategies to improve carbon capture and sequestration.
Although DFT is a powerful computational tool to study the atomic-scale adsorption phenomena, surface reactivity, phase behavior, and kinetic mechanisms of Cu in carbon sequestration mechanisms, experimental techniques such as electron microscopy and spectroscopy are needed to verify the results. In this regard, the Nion UltraSTEM (STEM is the abbreviation of Scanning Transmission Electron Micrsoscopy) microscope offers unique capabilities that can significantly contribute to understanding the functionalities of Copper (Cu) in carbon sequestration processes. Among the existing options, Nion UltraSTEM provides the highest resolution at the highest stability which can even results in the visualization of the phonons. Similar to other microscopes in this level, energy dispersive X-ray spectroscopy (EDXS) is being offered for elemental mapping and chemical analysis of Cu-containing materials. Furthermore, the Electron Energy Loss Spectroscopy (EELS) capabilities of the mentioned microscope enable the characterization of electronic and chemical bonding properties of Cu-based materials. In this regard, the oxidation state, coordination environment, and chemical bonding configurations of Cu atoms in various oxidation states can be determined. Surface characterization to investigate the surface defects, crystal facets, and surface reconstructions of Cu catalysts or sorbents can be developed to correlate the surface properties with catalytic activities and adsorption capacity. The obtained information will lead to tailored designs of Cu-nanostructures to improve carbon capture and sequestrations by controlling the size, shape, and morphology of Cu nanoparticles that result in optimized surface area, porosity, and active sites. Lastly, in-situ and operando studies can be developed to enable real-time imaging and spectroscopic analysis of Cu-based catalysts or sorbets under reaction conditions relevant to carbon sequestration processes.
Overall, the goal of this research is to provide insights into the applications of mean-field DFT and advanced STEM microscopy as computational and experimental tools to characterize copper-based materials in carbon capture and sequestration. The main novelty of this research is to provide future research directions aimed at optimizing Cu-based materials for enhanced capture and sequestration efficiency.

Keywords
: Mean field Density Functional Theory; Scanning Transmission Electron Microscopy (STEM); Carbon capture and Sequestration; Copper-based materials