Enhanced depolarization field of Ag/β-AgFeO_2-x by external magnetic field for efficient overall photoelectrocatalytic degradation and water splitting

Designing catalysts with appropriate band edge positions, excellent light absorption capabilities, and efficient charge transfer properties to achieve coupled pollutant degradation and energy recovery while maintaining high efficiency remains a significant challenge. In this study, we synthesized a narrow bandgap ferroelectric heterojunction, Ag/β-AgFeO_2-x (Ag/AFO), and demonstrated its high efficiency in both photoelectrocatalytic degradation and water splitting. Additionally, we designed an efficient photoelectrocatalytic reactor that promotes the generation and conversion of reactive oxygen species (ROS) at the cathode through the anode oxygen evolution reaction. Theoretical calculations and experiments revealed that Ag nanoparticles modulate the energy band structure of β-AgFeO_2-x (AFO), leading to a decrease in the d-band center (from −3.18 to −3.27 eV) and a reduction in the OER energy barrier (from 3.87 to 0.38 eV). Moreover, it was confirmed that the depolarization field of the ferroelectric Ag/AFO can be regulated not only by an electric field but also by an external magnetic field, accelerating electron transfer dynamics and extending carrier lifetime. Benefiting from these favorable factors, Ag/AFO exhibits outstanding overall photoelectrocatalytic performance, capable of driving both pollutant degradation and water splitting reactions at a cell voltage of 1.5 V.