Nitrogen doped carbon ribbons modified g-C3N4 for markedly enhanced photocatalytic H2-production in visible to near-infrared region

Designing carbonaceous materials modified g-C3N4-based photocatalytic system with broadband solar absorption from the visible to near-infrared (NIR) region for photocatalytic H-2 evolution (PHE) remains a big challenge. Herein, urea formaldehyde resin-carbonized nitrogen doped carbon (UFR-NC) ribbons modified g-C3N4 nanosheets were prepared by a facile thermal treatment method. Experimental results imply that g-C3N4/UFR-NC composites not only show larger specific surface area (SSA), better crystallinity and outstanding stability but also exhibit faster separation of charge carriers, in which the UFR-NC ribbons are more apt to accept electrons. Additionally, g-C3N4/UFR-NC composites possess superior optical adsorption from visible to NIR light and the band gap can be easily adjusted by changing the content of UFR-NC ribbons. Surprisingly, g-C3N4/UFR-NC0.02 exhibits the highest PHE activity (84.32 mu mol h(-1)), which is over 54.75 and 6.51 times higher than that of the g-C3N4 obtained by direct calcination of melamine (g-C3N4-M) and direct calcination of urea (g-C3N4-U) under visible light, and the apparent quantum efficiency (AQE) reaches 6.2% at 420 nm. In addition, the g-C3N4/UFR-NC0.02 displays an enhanced PHE activity of 26.59 mu mol h(-1) and 0.45 mu mol h(-1) under the blue visible (lambda = 475 nm) and NIR light irradiation (lambda > 800 nm). And the PHE activity of g-C3N4/UFR-NC0.02 has no obvious change after fourteen runs within 70 h. Our results suggest that constructing carbonaceous materials modified g-C3N4-based photocatalytic system will be a promising strategy to PHE.