Graphene-Regulated Interfacial Z-Scheme Charge Transfer for CO₂ Photoreduction to CO with Nearly 100% Selectivity

Graphitic carbon nitride (g-C3N4) exhibits considerable potential in CO2 photoreduction, although its photocatalytic performance remains suboptimal, primarily attributed to sluggish charge separation and slow water oxidation kinetics. Herein, a Z-scheme FeWO4/g-C3N4 heterojunction with graphene interfacial regulation is proposed as a prototype for CO2 conversion. Remarkably, the optimized one (30FeWO4/1G/g-C3N4) exhibits a CO evolution rate of 51.42 μmol g–1 h–1 accompanied by nearly 100% selectivity in pure water, showing an approximately 14-fold increase in photocatalytic activity compared to pristine g-C3N4. Comprehensive characterization through time-resolved photoluminescence (TR-PL) spectra, electron paramagnetic resonance (EPR) spectra, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses reveals that the performance enhancement is primarily attributed to the enhanced charge separation achieved by constructing the Z-scheme heterojunction and accelerated interfacial charge flow between g-C3N4 and FeWO4 with graphene introduction, along with the FeWO4 for water oxidation. This work offers a feasible pathway for the rational design of Z-scheme heterojunctions for artificial photosynthesis.