Beta-PdBi2 Monolayer: Two-Dimensional Topological Metal with Superior Catalytic Activity for Carbon Dioxide Electroreduction to Formic Acid

The lack of efficient electrocatalysts has been a main obstacle for the large-scale commercialization of CO2 electroreduction. In this work, we demonstrate that two-dimensional (2D) beta-PdBi2 mono-layer is a promising solution for this issue. beta-PdBi2 monolayer is a stable 2D crystal and the three-dimensional (3D) bulk interlayer energy is similar as for other layered materials that can be exfoliated into 2D crystals. Interestingly, beta-PdBi2 monolayer has rather intri-guing electronic properties: while being metallic, it also has a non-trivial topological point. Remarkably, the extra electronic states at the Fermi level induced by the intrinsic spinorbit coupling (SOC) effect significantly enhance the adsorption of OCHO* intermediate on beta-PdBi2 monolayer, resulting in a rather small onset potential of -0.26 V vs. RHE for CO2 electroreduction to HCOOH. These results not only suggest a promising candidate for CO2 electrolysis but also deepen our understanding of the factors dominating the catalytic activity of 2D materials.