Ordered and Ultralong Graphitic Carbon Nitride Nanotubes Obtained via In-Air CVD for Enhanced Photocatalytic Hydrogen Evolution

Abstract

Metal-free graphitic carbon nitride (g-C3N4) has become one of the most up-and-coming photocatalyst candidates for the hydrogen evolution reaction. However, the improvement in photocatalytic property is strongly suppressed by the limited active reaction sites due to the bulk microstructure of g-C3N4. On this basis, we exploit a moderate and economical approach to prepare an ordered and one-dimensionally ultralong carbon nitride nanotube (CN-NT) via the in-air chemical vapor deposition (CVD) with SiO2 nanofiber templates synthesized by electrostatic spinning. Due to the uniform size, fluffiness, and easy removal, SiO2 nanofiber templates are conducive to prepare ordered and tubular CN-NT. The obtained CN-NT sample exhibits an excellent photocatalytic hydrogen evolution rate (HER) of 4605.2 μmol·h–1·g–1 under visible light, which is 33.4 times higher than that of the original bulk g-C3N4. The apparent quantum efficiency reaches 6.49% at 420 nm. The enhancement in the photocatalytic activity is ascribed to the increased specific surface area, faster electron transfer pathway, advanced light absorption ability, and furthermore the lower recombination rate of photogenerated electrons.

Synergistically interactive MnFeM (M = Cu, Ti, and Co) sites doped porous g-C3N4 fiber-like nanostructures for an enhanced green hydrogen production

“…37 The photocatalytic HER rate of g-C 3 N 4 nanotubes (4605.2 μmol h −1 g −1 ) was 33.4 folds higher than that of bulk g-C 3 N 4 sheets, due to the porous nanotube morphology with a higher surface area and visible-light absorption capability. 47 Porous fiber-like is among the most promising g-C 3 N 4 nanostructures due to their high aspect ratio, accessible active sites, and durability against aggregation; however, they are rarely reported for the HER. We have previously developed a relatively green, simple, and one-pot approach for the synthesis of various one-dimensional g-C 3 N 4 nanostructures doped with binary noble metal atoms, such as PtPd/g-C 3 N 4 nanorods, Au/Pd/g-C 3 N 4 nanotubes, Au/Pd/g-C 3 N 4 nanotubes, Au/Pd/g-C 3 N 4 nanofibers, and Pd/Cu/g-C 3 N 4 nanowires based on the protonation of melamine and then annealing under N 2 for the CO oxidation reaction.…”

Simultaneous Dual-Functional Photocatalysis by g-C3N4-Based Nanostructures

“…They prepared hierarchical carbon nitride nanorods with carbon vacancies, which showed an excellent sonophotocatalytic performance for removing about 100% of tetracycline under visible-light irradiation . In another study, Wu et al prepared ultralong g-C 3 N 4 nanotubes via a CVD method and the obtained photocatalyst exhibited an excellent hydrogen evolution activity at a rate of 4605.2 μmol·h –1 ·g –1 , which was 33.4 times greater than that of the bulk g-C 3 N 4 . Several strategies, such as thermal, chemical, and ultrasonic exfoliation, were applied to obtain g-C 3 N 4 nanosheets.…”

“…h i b i t e d .excellent hydrogen evolution activity at a rate of 4605.2 μmol• h −1 •g −1 , which was 33.4 times greater than that of the bulk g-C 3 N 4 72. Several strategies, such as thermal, chemical, and ultrasonic exfoliation, were applied to obtain g-C 3 N 4 nanosheets.…”

Multiple ordered porous honeycombed g-C3N4 with carbon ring in-plane splicing for outstanding photocatalytic H2 production

“…6,7 However, pristine bulk g-C 3 N 4 exhibits a low hydrogen production rate (HER) and apparent quantum efficiency (AQE) because of its low specic surface area, poor electronic properties, insufficient light absorption and high recombination rate of photogenerated electron-hole pairs. 4,8 Accordingly, numerous modication methods have been explored to improve the photocatalytic activity of g-C 3 N 4 , such as element doping, 9,10 exfoliation, [11][12][13] multiple types of nanostructural designs, [14][15][16][17][18][19] coupling with other semiconductors and construction of metal-free heterojunctions. [20][21][22] The simultaneous morphology control and in-plane modication of highperformance g-C 3 N 4 with high yield is still challenging.…”