Preparation and photocatalytic performance of surface B atom-modified porous g-C3N4 composites

In this study, a series of boron-modified mesoporous g-C 3 N 4 composites (B-CN-x) were synthesized via a facile solvothermal method using boric acid as the boron source. Structural characterization revealed that boron atoms formed B-O-C chemical bonds on the material surface, which enabled directional electron migration from the g-C 3 N 4 framework to the boron sites through the oxygen-bridge structure. Compared with bulk g-C 3 N 4 , the B-CN-x composites delivered enlarged specific surface areas and superior photocatalytic performance. The maximum specific surface area of the modified materials reached 84.26 m 2 /g. Among all the samples, B-CN-0.010 exhibited the optimal catalytic activity, achieving degradation rates of 80.08% for 10 mg/L methyl orange and 94.08% for 40 mg/L rhodamine B under 60 min of visible-light illumination. After 120 min light irradiation, the TOC removal efficiencies of RhB and MO reach 65.50% and 73.83%, respectively. The adsorption kinetics of both RhB and MO were well-described by the PSO model. In the photocatalytic degradation system, the Elovich model showed the highest fitting degree for RhB, while the PFO model provided the optimal fit for MO. After five consecutive cycles, no significant loss in degradation efficiency was observed, demonstrating excellent reusability and stability. Mechanism quenching tests verified that·OH, h+ and ·O 2 − acted as the dominant reactive species. The enhanced photocatalytic activity can be attributed to the constructed B-O-C chemical bonds and porous structures.