Work-function-tailored electron transfer in 1D g-C₃N₄-HU/AC nanorods: ultrasonic-hydrothermal microstructure crafting for heavy metal ions photoreduction

In this paper, we developed a one-dimensional activated carbon (AC) coated graphitic carbon nitride (g-C 3 N 4 ) hybrid nanorods (CN HU/AC) synthesized via an ultrasonic-hydrothermal method. The dual modulation of ultrasonic cavitation and hydrothermal confinement enables simultaneous morphology engineering (1D nanorod formation) and inerfacial microstructure optimization, endowing CN HU/AC with exceptional photoelectron transfer properties. Comparative studies with pristine g-C 3 N 4 and hydrothermally modified CN HU without AC addition reveal that the optimal AC loading (CN HU/AC5) achieves remarkable Cr(VI) photoreduction under visible light, exhibiting rate constants 6.6 times and 2.1 times higher than those of g-C 3 N 4 and CN HU, respectively. This enhancement originates from synergistic effects: (1) AC’s photosensitization broadens light absorption while its coating establishes intimate interfacial contact for accelerated charge transfer; (2) The 1D architecture directs axial elctron transport, coupled with surface C = O / O = C OH groups acting as electron traps; (3) Citric acid functions as both hole scavenger and Cr(VI) complexation agent to lower reduction barriers. This study establishes a paradigm for designing carbon-coupled heterostructures for the sustainable heavy metal remediation.