Basal Plane Activation via Grain Boundaries in Monolayer MoS2 for Carbon Dioxide Reduction

With the electrochemical carbon dioxide reduction reaction (CO2RR) being a promising method to reduce atmospheric carbon dioxide (CO2), transition metal dichalcogenides (TMDCs), such as molybdenum disulfide (MoS2), have recently risen as potential catalysts for CO2RR. However, pristine TMDCs are bottlenecked by the insufficiency of active sites in the basal plane. In this study, focusing on polycrystalline MoS2, we perform systematic density functional theory calculations to investigate the role of grain boundaries (GBs) on the catalytic performance of MoS2 for CO2RR. Our results show that most GBs contribute to lowering the reaction energy of the potential-limiting step in CO2RR. This effect can be further amplified with the introduction of S vacancies. In addition, the introduction of GBs with vacancies is shown to act as an effective method to break the scaling relations between reaction intermediates, which is crucial in improving catalytic efficiencies. Our findings demonstrate that defect engineering holds great potential to activate the basal plane of TMDCs for CO2RR, providing valuable insights into engineering TMDCs for high-performing CO2RR electrocatalysts.