Multiscale modification of carbon nitride-based homojunction for enhanced photocatalytic atrazine decomposition

[Display omitted] •PDI-g-C3N4/g-C3N4 (CPH) has been fabricated via multiscale modification strategy.•CPH exhibited excellent photocatalytic atrazine removal efficiency.•The mesoporous morphology of CPH enhanced the accessibility of contaminant.•The PDI decoration of CPH promoted light-harvesting and π-conjugation.•The construction of homojunction suppressed the recombination of photocarrier. Herein, PDI-g-C3N4/g-C3N4 homojunction has been fabricated via the multiscale modification strategy to enhance photocatalytic atrazine degradation. The morphological scale modification was realized by multistep thermal condensation, where the released gas could act as templates to form the porous structure. The molecular scale modification was achieved by the pyromellitic diimide (PDI) decoration, which could distort the planar nanosheet to induce a porous structure and provide more chromophores for better light absorption. The electronic scale modification was realized by the built-in electric field between the PDI-g-C3N4/g-C3N4 homojunction interfaces, which suppressed the recombination of photocarriers. The PDI-g-C3N4/g-C3N4 strengthened photocatalytic atrazine degradation was well-adapted to different environmental influence interference. The optimum atrazine degradation rate within one hour reached 90% in a strong acidic condition (pH = 3.09). It was found that the highly pH-dependent ATZ removal is related to the H2O2 generation during photocatalysis. Within one hour, the PDI-g-C3N4/g-C3N4 could generate 147.38 μM H2O2. In addition, 1O2, ·O2-, h+, and ·OH were found to have contributed to the ATZ decomposition. During photocatalysis, 14 intermediates and three pathways for atrazine degradation have been found. Hopefully, this study could pave a way for the development of the multiscale modification for the photocatalyst.