Highly dispersed cerium doping induced amorphization of tubular g-C3N4 for weakening exciton effects and boosting CO2 photoreduction

Graphitic carbon nitride (g-C 3 N 4 ) holds great promise for photocatalytic CO 2 reduction, but its performance is critically limited by strong excitonic effects that hinder charge separation and migration. Herein, a highly dispersed Ce-doped tubular g-C 3 N 4 framework was designed to induce a tailored amorphous phase transition, fundamentally modifying its electronic and structural properties. The amorphization creates a static exciton self-trapping network that reduces the exciton binding energy from 65 to 54.3 meV and generates a robust localized built-in electric field, driving spatial separation and directional charge migration along the one-dimensional tubular channels. Meanwhile, Ce 3+ /Ce 4+ redox couples act as a dynamic electron buffer, kinetically capturing and shuttling electrons. Consequently, the optimized 3%Ce-TCN achieves a CO production rate of 87.31 μmol/(g·h) under visible light, a 2.5-fold enhancement over pristine TCN, with an apparent quantum efficiency of 0.799% at 420 nm. In-situ Fourier transform infrared (FTIR) and density functional theory (DFT) calculations confirm that the Ce sites lower the energy barrier for key *COOH intermediate formation. This work establishes a new paradigm for manipulating exciton dynamics and carrier migration through rare earth-doping-induced microstructural engineering.