Deciphering the regulatory mechanism of electrocatalytic activity in an Fe-anchored CuInP ₂ S ₆ monolayer <i>via</i> ferroelectric switching and in-plane strain

Single-atom catalysts (SACs) have attracted considerable attention due to their extremely high atomic utilization and tunable electronic structures. However, the precise control of their catalytic activity and selectivity remains a significant challenge affecting catalytic efficiency. Meanwhile, the development of two-dimensional (2D) materials offers new opportunities for optimizing the catalytic efficiency of SACs, especially 2D ferroelectric materials, whose intrinsic polarization properties and bistable states switchable under an external electric field, provide new ideas for regulating the local electronic structure of SACs. In this work, based on first-principles calculations, we systematically investigated the activity regulation mechanism of iron (Fe)-anchored 2D ferroelectric CuInP₂S₆ (Fe-anchored CIPS) as a bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Our findings reveal that the switching of polarization direction in the ferroelectric layer can significantly alter the local charge distribution around Fe and the adsorbate. Based on the adsorption energy mechanism and d-band center analysis, it can be observed that the switching of the polarized-state can achieve different catalytic selectivity. More importantly, in-plane strain can be used as an independent and effective regulation tool to continuously adjust the ferroelectric properties of CIPS, thereby synergistically influencing the electronic distribution and further optimizing catalytic activity. This study demonstrates that 2D ferroelectric substrates provide a more abundant and stable regulation means for SACs, offering a new platform and research direction for designing highly efficient multifunctional SACs.