Vacancy-control of g-C3N4 microtubular through C/N atomic modulation for boosted photocatalytic hydrogen peroxide production

Graphitic carbon nitride (g-C 3 N 4 ) is a promising photocatalyst with broad applicability. Yet, its performance is frequently hindered by intrinsic drawbacks such as insufficient visible light absorption, poor surface area, and fast recombination of charge carriers. Therefore, the highly porous carbon-doped g-C 3 N 4 (CCN) microtubular were synthesized by a simple and practical synthesis utilizing silica as a hard template for the porous structure and carbon doping derived from cellulosic kapok fiber bio-templates. The findings indicated that the modification effectively tailored the band gap, extended its light absorption into the near-infrared region, and increased hydrogen peroxide (H 2 O 2 ) production. The 15S-CCN photocatalyst prepared by 15 % silica-coated kapok fiber produces the highest rate of H 2 O 2 at 1697.37 μM g −1 h −1 , which is 2.4 times higher than pristine g-C 3 N 4 . The porous microtubular structure efficiently extends the CCN light absorption and improves the effectiveness of light energy conversion. Besides, the appearance of carbon doping and nitrogen defects has significantly suppressed the charge recombination and facilitated the migration of photogenerated charge carriers, as evidenced by a reduction in PL intensity. These responses have improved the photocatalytic performance of the CCN. Besides, the radical trapping experiment has validated the dominant role of photogenerated electrons and holes in the photocatalytic system, and in line with the proposed band structure, which favors a direct two-electron transfer pathway for oxygen reduction reaction, offering a promising strategy for sustainable solar fuel production. This study unveils exciting approaches for creating porous microtubular CCN structures designed to significantly enhance solar fuel production. • Highly porous CCN microtubular structures with nitrogen vacancies and carbon doping • Widened light absorption into NIR region and narrowed band gap of highly porous CCN • Presence of nitrogen defects promotes migration of photogenerated charge carriers. • Synergistic effects of the modification approaches enhance the H 2 O 2 production.