Amorphous-Crystalline FeOOH/COF S-Scheme Heterojunctions: Internal Electric Field-Modulated Charge Dynamics for Efficient CO2 Conversion.

Designing stable photocatalysts with optimized charge transfer and surface kinetics remains a critical challenge for achieving solar-driven CO2 reduction. In this work, an amorphous FeOOH/covalent organic frameworks (COFs) S-scheme heterojunction was rationally constructed via a solvent-assisted strategy. The integration of defect-rich amorphous FeOOH with the porous COFs matrix not only maximizes the interfacial contact but also induces a strong internal electric field (IEF), enabling directional charge migration and efficient carrier separation. The optimized amorphous FeOOH/COF3 heterostructure exhibits a CO evolution rate of 200.98 μmol·g-1·h-1 with a selectivity as high as 93.6% under visible-light irradiation, outperforming the individual components. Spectroscopic and photoelectrochemical studies confirm that the built-in electric field can effectively regulate the formation of an S-scheme charge transfer pathway, which retains the highly reducing electrons on COFs while maintaining the excellent oxidation capability of FeOOH. This work highlights the crucial roles of amorphous/crystalline interface engineering and IEF modulation in constructing high-performance COFs-based photocatalysts and provides new insights into designing efficient S-scheme systems for solar-driven CO2 conversion.