Unveil the Potential-Dependent Electrochemical Formate Formation on Topological PtBi2 Monolayer

The lack of efficient catalysts has become a major obstacle to the large-scale commercialization of electrochemical CO2 reduction (ECR). Two-dimensional semi-metallic PtBi2 has garnered increasing attention due to its distinctive topological properties, superconductivity, and abundant active centers. In this work, comprehensive density functional theory calculations were performed to investigate the ECR performance of PtBi2 monolayer. An advanced constant potential model was employed to resolve the theory and experiment contradictions caused by ignoring the charge effect throughout the ECR process in the traditional constant charge model. We also simulated the polarization curve using the microkinetic method. We derived the current density of formate formation at different potentials and compared it with experimental values. Our results show that the limiting potential (UL) of formate formation on PtBi2 monolayer is −0.26 V, which is much lower than that of bismuth-based catalysts (−0.49 V) widely reported. The competitive CO and H2 formation can be suppressed (UL > −1.0 V). Especially at −0.54 V vs SHE, PtBi2 monolayer achieves a large current density (about ∼200 mA/cm2). Based on the electronic structure analysis, we found that the coinfluence of the intrinsic spin–orbit coupling effect and Pt–Bi synergistic effect is the fundamental reason for an enhanced *OCHO adsorption on PtBi2. Our work provides a promising candidate PtBi2 monolayer for formate formation and a systematic research framework for designing advanced ECR catalysts.