Phenyl-Bridged Graphitic Carbon Nitride with a Porous and Hollow Sphere Structure to Enhance Dissociation of Photogenerated Charge Carriers and Visible-Light-Driven H₂ Generation

Abstract

Graphitic carbon nitride (CN) suffers from rapid recombination of photoexcited charges due to the existing highly symmetrical tri-s-triazine ring and long charge diffusion path, resulting in moderate photocatalytic activity. The bridged phenyl embedded in the CN structure was used to reduce the symmetry of the tri-s-triazine ring. In addition, the CN material was constructed with a porous and hollow sphere structure to shorten the diffusion path of charge carriers. Herein, simple thermal polymerization of a trimesic acid-doped melamine–cyanuric acid (MCA) supramolecular was employed to construct phenyl-bridged graphitic carbon nitride (Ph-CN-MCA) with a hollow sphere structure composed of porous nanosheets for visible-light catalytic H2 evolution. The porous and hollow sphere-structured Ph-CN-MCA possessed increased degree of polymerization, more negative conduction band potential, enlarged Brunauer–Emmett–Teller (BET) surface area, and shortened charge diffusion path. In addition, bridged phenyl embedded in the Ph-CN-MCA structure not only accelerated the dissociation of photogenerated carriers but also narrowed the band gap and extended the visible-light absorption. Further, the separated highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of Ph-CN-MCA facilitated the spatial dissociation of photogenerated charges, which was also confirmed by theoretical calculations. As a consequence, compared with the reference CN-MA catalyst prepared from melamine, Ph-CN-MCA showed approximately 48.42 times the photocatalytic H2 evolution under visible-light irradiation. The developed synthetic method herein highlights that phenyl-bridged graphitic carbon nitride with a porous and hollow sphere structure could provide an efficient platform to boost the dissociation of photoexcited charge carriers and photocatalytic H2 evolution.

Instantaneous Sonophotocatalytic Degradation of Tetracycline over NU-1000@ZnIn2S4 Core–Shell Nanorods as a Robust and Eco-friendly Catalyst

“…26,27 To develop such type of processes, there is a need for the design of high-performance photocatalysts. 28 Diverse semiconductor substances such as metal oxides, oxynitrides, sulfides, and metal-free semiconductors were tested for the photocatalytic degradation of antibiotics. 29,30 However, metal sulfides with robust adsorption in the visible light zone are viewed as acceptable alternative photocatalysts for the degradation of antibiotics.…”

Semi‐Synthetic Chlorophyll‐Carotenoid Dyad for Dye‐Sensitized Photocatalytic Hydrogen Evolution

“…Thus development of photocatalysis for PHE is considered to be a matter of central focus to solve the problem of energy shortage and environmental pollution. [4][5][6] PHE systems based on various kinds of semiconductors have been extensively investigated so far, [7,8] among which Pt/TiO 2 has been regarded as one of the most major photocatalysts. [9][10][11][12][13] To overcome the inherent defects of TiO 2 such as large band gap which leads to low photocatalytic efficiency, some research groups reported the development of dye-sensitized Pt/TiO 2 photocatalysts for hydrogen evolution.…”

Photocatalytic Reduction of Aromatic Nitro Compounds with Ag/AgxS Composites under Visible Light Irradiation

“…The charge carrier separation was verified by photoluminescence (PL) (Figure S4). The intensity of fluorescence signal at 450–500 nm showed a gradually decrease with l -cys/Ag + molar ratio increasing from 0.5 to 1, but a gradually increase with l -cys/Ag + molar ratio increasing from 1 to 8, suggesting that Ag/Ag x S-1 had the lowest recombination rate of electrons and holes under visible light irradiation. − Therefore, Ag/Ag x S-1 owned the strongest ability to oxidize S 2– to polysulfide S 2 2– and S 4 2– in aqueous solution.…”