Advancing n-π* electron transition of carbon nitride via distorted structure and nitrogen heterocycle for efficient...

To adequately utilize solar energy for water pollution remediation, tailoring graphite carbon nitride (CN) with sufficient active sites exposure, visible-light harvest and eminent charge separation/migration/recombination efficiency, has long been pursuing. Herein, a pyrazine doped distorted architecture CN with advancing n-π* electron transition was tailored via one-pot thermal-melting assemble following thermal-induce copolymerization of pyrazine-2,3-dicarboxylic acid and urea. Various characterizations verify the successful construction of distorted porous thin wall CN. The nitrogen adsorption-desorption, photoelectric and band structure analysis manifest that the optimized 20-PACN sample possesses propelled visible-light capture ability with wavelength above 500 nm, more active sites exposure with high specific surface area and hybrid electron structure with distinctly improved charge separation/migration/recombination efficiency. More importantly, 10 mg of 20-PACN can photodegradation 97 % of tetracycline (91 % of rhodamine B or 91 % of methylene blue) within 100 min, which is 7.1 times of bulk counterparts. ESR and quenching tests confirm that apart from h⁺, ⋅O₂^- and ¹O₂ significantly assist to the photodegradation reaction, which profit from upshifted CB and the appearance of intermediate state. The mass spectrum, toxicity prediction and on-line infrared spectroscopy explicated intermediates, routes and toxicity, as well as real-time monitor the variation of functional groups during photodegradation reaction. At last, combined the above test characterization and density functional theory analysis, a potential propelled mechanism of photodegradation was proposed.