<p>The escalating global energy demand has spurred the emergence of diverse solar-powered systems. As a typical example, photocathodic protection (PCP) is a promising technology to prevent metal corrosion via a “solar-electric-chemical” energy conversion process. However, the implementation of reported PCP systems has been greatly restricted by two key issues, that is, severe electron–hole recombination and sluggish surface water oxidation reaction. Herein, we report a high-performance bilayer PCP photoanode composed of single-domain ferroelectric PbTiO₃ nanoplates at the bottom and NiCo-LDH nanosheets at the top. Controlled external poling aligns the depolarization fields of individual PbTiO₃ nanoplates and adds up to a much enhanced “macroscopic electric field” through the entire photoanode, which is harnessed to steer the charge flow inside the PCP system. In addition, the integration of NiCo-LDH nanosheets on top of the PbTiO₃ nanoplates not only introduces an electric field at the heterostructure interface to further promote the interfacial charge transfer, but more importantly, accelerates the oxygen evolution reaction (OER) kinetics and suppresses the electron–hole recombination. Such a rational design allows for the synergistic contribution of the ferroelectric polarization of PbTiO₃ and the superior OER catalytic activities of 2D LDH to the overall energy conversion efficiency, leading to stable cathodic protection for 304 stainless steel. This work provides a feasible design strategy for efficient PCP systems through precise optimization of the core photoelectrochemical reaction steps.</p> Graphical Abstract <p>A “ferroelectric-catalytic” bilayer was tailored to harness synergistic contributions from the intrinsic spontaneous polarization of ferroelectrics and the superior water oxidation activity of catalysts to improve “solar-electric-chemical” energy conversion for efficient cathodic metal protection.</p> <p></p>