The Synergy\nof the Electric Polarization and Built-In\nElectric Field for Efficient OER/ORR Supported on 2D Ferroelectric\nTM-Gr@Ga<sub>2</sub>O<sub>3</sub> Heterojunctions Using Constant-Potential\nMethods

The pursuit of efficient oxygen reduction and evolution\nreactions\n(ORR/OER) using non-noble-metal catalysts is a coveted goal, yet it\npresents considerable challenges. In this study, we utilize first-principles\ncalculations to engineer heterojunctions by integrating Ga<sub>2</sub>O<sub>3</sub> monolayers with transition metal-doped graphene (TM-Gr)\nand then systematically evaluate the catalytic performance of these\nTM-Gr@Ga<sub>2</sub>O<sub>3</sub> heterojunctions in the OER and ORR.\nOur results reveal that the synergistic effect of the built-in electric\nfield created by the charge transfer and the Ga<sub>2</sub>O<sub>3</sub> electric polarization markedly enhances the catalytic activity for\nOER/ORR. Altering Ga<sub>2</sub>O<sub>3</sub> polarization orientations\nsynergistically affects interfacial charge transfer and monolayer\ncharge distribution. This involves charge redistribution across monolayers\naligned with intrinsic interfacial charge transfer, including both\ninterfacial and intralayer transfer, driven by the system’s\ninherent polarization. Using a constant charge approach, 69 systems\nwere evaluated as the potential electrocatalysts, including TM-Gr,\nTM-Gr@Ga<sub>2</sub>O<sub>3</sub>↑, and TM-Gr@Ga<sub>2</sub>O<sub>3</sub>↓, for which TM-Gr@Ga<sub>2</sub>O<sub>3</sub> produces more high-performance catalyst candidates compared with\nTM-Gr. Furthermore, detailed analysis of highly active catalysts based\non the constant-charge method such as Co-Gr@Ga<sub>2</sub>O<sub>3</sub>↓, Co-Gr@Ga<sub>2</sub>O<sub>3</sub>↑, and Ni-Gr@Ga<sub>2</sub>O<sub>3</sub>↑ through constant-potential assessment\nand microkinetic modeling revealed the best performance with overpotentials\nof 0.23 (OER) and 0.21 V (ORR) and half-wave potentials of 0.85 V\nand potentials of 1.36 V at a current density of 10 mA cm<sup>–2</sup> in acidic or alkaline conditions. This research provides a theoretical\nfoundation for developing efficient nonprecious metal electrocatalysts.