Three-Dimensional Hierarchical g-C₃N₄ Architectures Assembled by Ultrathin Self-Doped Nanosheets: Extremely Facile Hexamethylenetetramine Activation and Superior Photocatalytic Hydrogen Evolution

Abstract

Photocatalytic hydrogen evolution has broad prospects as a clean solution for the energy crisis. However, the rational design of catalyst complex, the H 2 evolution efficiency, and the yield are great challenge. Herein, three-dimensional hierarchical g-C 3 N 4 architectures assembled by ultrathin carbon-rich nanosheets (3D CCNS) were prepared via an extremely facile hexamethylenetetramine activation approach at the bulk scale, indicating the validation of scale-up production process. The two-dimensional ultrathin carbon-rich nanosheets were several hundred nanometers in width but only 5−6 nm in thickness and gave rise to a unique 3D interconnected network. The unique composition and structure of the nanosheets endow them with a remarkable light absorption spectrum with the tunable band gap, high electrical conductivity, fast charge separation, and large surface areas with abundant reaction active sites, and thus significantly improved H 2 production performance. As high as ∼7.8%, quantum efficiency can be achieved by irradiating 3D CCNS at 420 nm with a H 2 evolution rate >2.7 × 10 4 μmol/g/h, which is ∼31.3 times higher than that of the pristine g-C 3 N 4 . Our work introduces an extremely facile route for mass production of doping modified 3D g-C 3 N 4 -based photocatalyst with excellent H 2 evolution performances. KEYWORDS: 3D hierarchical g-C 3 N 4 architectures, ultrathin self-doped nanosheets, tunable band structures, photocatalytic hydrogen evolution

Flower-like NiCo2O4–CN as efficient bifunctional electrocatalyst for Zn-Air battery

“…The peaks in the range of 1200-1700 cm -1 can be attributed to the C=N stretching and C-N bonds. The peak locating at 811 cm -1 is origin from the out-of-plane bending of heptazine rings [24,28]. As for pure NiCo 2 O 4 , it mainly displays the peak below 700 cm -1 , which is the typical IR spectra of metal oxide.…”

0D CoP cocatalyst/ 2D g‐C3N4 nanosheets: An efficient photocatalyst for promoting photocatalytic hydrogen evolution

“…As a visible light responsive metal‐free polymer semiconductor, g‐C 3 N 4 , has good thermal/chemical stability, electronic and optical properties, and is widely used in the field of solar energy conversion . The conduction band potential of g‐C 3 N 4 is −1.3 eV (vs, NHE, pH = 7), photogenerated electrons generated under visible light excitation have strong reduction ability . Moreover, the surface group of g‐C 3 N 4 is negatively charged to help build a composite photocatalytic system with other semiconductors.…”

“…[8][9][10] The conduction band potential of g-C 3 N 4 is −1.3 eV (vs, NHE, pH = 7), photogenerated electrons generated under visible light excitation have strong reduction ability. [11][12][13][14] Moreover, the surface group of g-C 3 N 4 is negatively charged to help build a composite photocatalytic system with other semiconductors.…”

Hydrothermal Synthesis of g‐C3N4/NiFe2O4 Nanocomposite and Its Enhanced Photocatalytic Activity

“…On the other hand, there are still a number of shortcomings related with g‐C 3 N 4 that limited its efficient photocatalytic activities. The most important limitations are (a) low specific surface area, (b) fast charge recombination, and (c) poor visible‐light absorption . Furthermore, the recyclability of g‐C 3 N 4 after use is not an easy and high amount of g‐C 3 N 4 losses during separation using filtration or centrifugation .…”