Utilizing Density Functional Theory to Study the Carbon Dioxide Reduction Reaction on Variants of Monolayer MoSSe*

Throughout the past decade, two-dimensional transition metal dichalcogenides (2D TMDs) have been

studied extensively as alternatives to noble metal electrocatalysts for carbon dioxide reduction (CRR)

and transformation into usable fuels. Two-dimensional Janus TMDs are asymmetrical variations of regular TMDs,

where the chalcogenide layers are different. Such structures have interesting adsorption properties due

to the intrinsic magnetic moment between their layers. We study adsorption of various CRR reactants

and products (ie. CO and CH₄) on both sides of monolayer MoSSe via first-principles, density functional

theory (DFT) calculations. We compare our results to MoSe ₂, and we introduce chalcogenide vacancies

and Cu dopants to both materials, both of which raise adsorption energy of the CRR intermediates

compared to the bare TMD case. For instance, CO adsorbed to the S-side of MoSSe has adsorption

energies of -0.12 eV, -0.18 eV, and -1.25 eV for the bare, S-vacancy, and Cu defect cases respectively. We

detail the favored reduction pathway of each material by comparing the free energies of the adsorbed

CRR intermediates. The results serve to aid in the identification of potential CRR catalysts, and are to be

used as a reference for further investigation.