Facile synthesis of nitrogen-deficient mesoporous graphitic carbon nitride for highly efficient photocatalytic performance

A visible-light-driven photocatalyst nitrogen-deficient mesoporous graphitic carbon nitride (mpg-C3N4-delta) was prepared by a thermal polymerization-assisted colloidal crystal templating method. The unique mesoporous structure of mpg-C3N4-delta was confirmed to be formed with relatively uniform pores and cyano groups (-C N)-related nitrogen defects, which were generated from the break of the -C = N bonds of triazine rings and the subsequent loss of terminal NHx species during the pore-making process. Benefiting from the larger surface area, suitable energy level and increased unpaired electrons on C atoms of aromatic rings, the photocatalytic activity of mpg-C3N4-delta for RhB degradation was 11 and 2.6 times higher than that of bulk g-C3N4 and mpg-C3N4, respectively, under visible light irradiation (lambda >= 420 nm). Furthermore, nitrogen defects in mpg-C3N4-delta were verified to serve as electron/hole traps to boost the separation and transfer of photoexcited charge carriers and thus enhanced the production of main active species h(+) and O-2.(-), resulting in the efficient destruction of the intrinsic structure and functional groups of RhB molecules into small molecules. This work highlights that construction of uniform mesoporous architectures with surface nitrogen defects could be useful for developing highly efficient metal-free photocatalysts.