Perovskite Oxide for Photoelectrochemical Water Splitting and Purification: Polarization Field Engineering

Perovskite oxide photoelectrodes enable efficient photoelectrochemical (PEC) energy conversion and environmental remediation due to tunable bandgaps, high stability, and inherent multifunctionality. While their conventional PEC applications have been extensively reviewed, their emerging role under piezoelectric, ferroelectric, and pyroelectric polarization fields remains inadequately systematized. This review systematically summarizes recent advances in enhancing the performance of PEC water splitting and water purification using piezoelectric, ferroelectric, and pyroelectric polarization fields in perovskite oxide photoelectrodes. The fundamental mechanism by which external stimuli (mechanical stress, electric fields, and thermal gradients) generate these intrinsic polarization fields within the structure of perovskite oxides is elucidated. Additionally, the relationship between polarization fields and charge separation in the PEC water splitting and purification is comprehensively investigated, and the synergistic effects of multiple coexisting polarization effects are explored. The practicality of polarization fields in perovskite oxide PEC water splitting and purification is demonstrated through case studies. Finally, we propose a key framework and forward-looking perspective for designing the next generation of stimulus-responsive perovskite photoelectrodes, aiming to integrate these effects under actual operating conditions by combining fundamental theory with scalable, high-performance, multifunctional PEC systems, thereby supporting the development of water-energy coupled technologies.