Defect engineering of Z-scheme heterojunction catalysts for efficient CO2 photoreduction

Defect-engineered Z-scheme heterojunction catalysts (Fe-O v 300/PCN) exhibit remarkable improvements in photocatalytic CO 2 reduction performance, attributed to their enhanced charge separation and stable structural features. By introducing oxygen vacancies (O v ) in Fe 2 O 3 and coupling it with polymeric graphitic carbon nitride (PCN), the catalyst achieves superior activity compared to conventional materials. The unique Z-scheme charge transfer mechanism facilitates efficient carrier dynamics, while the robust interface between components ensures long-term stability. This design promotes effective CO 2 adsorption and reaction pathways, showcasing the potential of combining defect engineering with heterojunction strategies to advance sustainable energy conversion and environmental technologies. • Defect-engineered Fe-O v 300/PCN forms a Z-scheme heterojunction for photocatalysis. • Fe-O v 300/PCN achieves 106 μmol g -1 h −1 CH 4 , 12 times higher than pristine PCN . • Z-scheme design enables efficient charge separation, prolonging carrier lifetimes. • Isotope study & DFT confirm Z-scheme, ensuring stability & sustained performance. Photocatalytic CO 2 reduction coupled with water oxidation for the generation of valuable hydrocarbons represents a promising solution to address the challenges in sustainable energy production and clean environments. However, the limited efficiency of conventional photocatalysts due to their rapid charge recombination and insufficient visible-light utilization remains a bottleneck. Herein, we report defect-engineered Z-scheme heterojunction catalysts to overcome these challenges. Fe-O v 300/PCN was synthesized via precise control of oxygen vacancies in α-Fe 2 O 3 and integrated with polymeric graphitic carbon nitride (PCN) and showed significantly enhanced photocatalytic activity for CO 2 reduction. Comprehensive characterization by X-ray diffraction, transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS) revealed robust interfacial electronic coupling and stable structural integrity. Photocatalytic CO 2 reduction tests under visible light irradiation showed a CH 4 production rate of 106 μmol g -1 h - 1 , approximately 12 times that of pristine PCN and significantly higher than benchmark α-Fe 2 O 3 /PCN. Mechanistic investigations by UV–vis diffuse reflectance spectroscopy, electron paramagnetic resonance, and in-situ XPS confirmed the establishment of a direct Z-scheme charge transfer pathway with efficient separation and prolonged carrier lifetimes. This work demonstrates the potential of defect engineering and heterojunction design in advancing CO 2 conversion technologies for sustainable energy production and ensuring clean environments.