Programmable photocatalytic CO2 reduction: Ferroelectric polarization switching for on-demand reversible product selectivity on Pd SAC/In2S3 monolayer

Abstract

Precise regulation of reaction pathways and product selectivity is the long-standing core bottleneck of photocatalytic CO₂ reduction for greenhouse gas valorization. Conventional photocatalysts with static active sites are locked into fixed reaction pathways once synthesized, failing to meet the on-demand product switching demand in complex CO₂ reduction reaction (CO₂RR) networks. Herein, we systematically investigate the regulation of ferroelectric polarization direction on the electronic structure and CO₂RR performance of Pd single-atom active sites via first-principles calculations based on the room-temperature ferroelectric α-In₂S₃ monolayer. We reveal that the intrinsic ferroelectric polarization promotes the photogenerated carrier separation and, dynamically tunes the d-band center and charge state of Pd active centers. This modulation optimizes the adsorption of key intermediates and reduces the energy barrier of the rate-determining step (RDS) by 0.68 eV. More importantly, polarization reversal realizes the fully reversible switching of CO₂ initial hydrogenation pathways between ∗HCOO and ∗COOH, thus achieving on-demand selective generation of C1 products including HCOOH, CO, CH₃OH and CH₄. Meanwhile, the activity of the competitive hydrogen evolution reaction (HER) can be synchronously tuned to optimize CO₂RR selectivity. This work breaks the traditional paradigm of static catalyst design, establishes a complete theoretical framework for programmable photocatalysis, and provides solid theoretical guidance for next-generation tunable CO₂ conversion systems.