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

Abstract

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.