Enhancing the performance of electrocatalysts for applications like carbon conversion is important for making that technology viable. Nanoconfinement is a promising strategy for doing so. Understanding how it is created and why it enhances reaction rates can lead to a better characterization of nanoconfinement– the first step towards smarter nanoconfined catalyst design. A nanoconfined microenvironment is a characteristic feature of the activated silver nanoparticle/ordered ligand interlayer catalyst. This nanoconfined region is hypothesized to facilitate CO 2 electrochemical reduction to CO at selectivities as high as 98% compared to H 2 . We use density functional theory to a) study conditions to create nanoconfinement, b) design systems to create it more energy efficiently, and c) demonstrate why it enhances CO 2 reduction in this catalyst. First, we show that nanoconfinement can only be created at highly negative potentials. As the potential becomes more negative, the surface repels the ligand more strongly, causing it to detach from the surface one bond at a time. At highly negative potentials, the ligand completely detaches, forming a pocket in the metal/ligand interlayer. This is the nanoconfined pocket. Second, we explore ways to create nanoconfinement efficiently by decreasing the magnitude of the potential needed to build it. Since the charge transfer between Au and the ligand is lower than Ag, it is easier to detach the ligand and create nanoconfinement at lower potentials in Au-doped catalysts. The opposite is true for Cu dopants. Further, we show that this phenomenon can be captured by electronegativity differences between the metal and ligand. Finally, we investigate CO 2 reduction reaction rates under nanoconfinement. The reaction intermediates adsorbed on the surface are further stabilized by the dipole interactions with the confining ligand. Thus, by stabilizing key intermediates, nanoconfinement enhances overall reaction rates. This series of computational investigations is advancing our understanding of electrochemistry under confinement, offering a new way to improve CO 2 RR conversion efficiency.
Biography:
Dr. Asmita Jana is a postdoctoral researcher in the Chemical Sciences Division at Lawrence Berkeley National Laboratory. Her research uses computational materials science to study carbon capture and conversion by modeling interactions in electrochemical interfaces. She holds a PhD in Materials Science and Engineering from MIT where she worked on modeling fluid permeation through graphene-based membranes and crosslinking in aromatic molecules to generate carbon fibers. She is also an advocate for women in STEM. She regularly volunteers to promote STEM awareness in the local community.
