Density Functional Theory Investigation of Structure–Activity Relationship for Efficient Electrochemical CO₂ Reduction on Defective SnSe₂ Nanosheets

Developing efficient strategies to optimize the performance of electrocatalysts is essential for practical applications of electrochemical CO2 reduction, which, however, remains a great challenge. In this work, by means of density functional theory calculations, we report a surface defect-size engineering strategy to optimize the catalytic activity of two-dimensional SnSe2 nanosheets for CO2 reduction. Our results show that the basal plane of SnSe2 can be activated through the formation of an Se vacancy, where the CO2 can be efficiently captured and reduced into CH4 with a low limiting potential of −0.58 V. In addition, a structure–activity relationship has been established, which shows that the limiting potential can be further reduced by adopting external strain to tailor the Se vacancy to an optimal size. This work not only highlights a very promising catalyst for CO2 reduction but also provides an efficient way to tailor the catalysts to achieve enhanced activities and high selectivity.