Surface Amino Group Regulation and Structural Engineering of Graphitic Carbon Nitride with Enhanced Photocatalytic Activity by Ultrafast Ammonia Plasma Immersion Modification

Abstract

Surface amino group regulation and structural engineering of graphitic carbon nitride (g-CN) for better catalytic activity have increasingly become a focus of academia and industry. In this work, the ammonia plasma produced by a microwave surface wave plasma generator was developed as a facile source to achieve fast, controllable surface modification, and structural engineering of g-CN by ultrafast plasma treatment in minutes, thus enhancing photocatalytic performance of g-CN. The morphology, surface hydrophilicity, optical absorption properties, and states of C–N bonds were investigated to determine the effect of plasma immersion modification on the g-CN catalyst. The structure and photoelectric features of the plasma-modified samples were characterized by X-ray diffractometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The results indicate that the ammonia plasma-treated g-CN–NH3 exhibits an ultrathin nanosheet structure, enriched amino groups, and an ideal molecular structure, a narrower band gap (2.35 eV), extended light-harvesting edges (560 nm), and enhanced electron transport ability. The remarkably enhanced photocatalytic activity demonstrated in the photoreduction and detoxification of hexavalent chromium (Cr­(VI)) can be ascribed to the optimization of the structural and photoelectric properties induced by the unique ammonia plasma treatment. The effective and ultrafast approach developed in this work is promising in the surface amino group regulation and structural engineering of various functional materials.

Fe3O4-Loaded g-C3N4/C-Layered Composite as a Ternary Photocatalyst for Tetracycline Degradation

“…13 Therefore, several strategies have been developed to enhance the photocatalytic performance of g-C 3 N 4 , such as porous structure design, metal or nonmetal element doping, surface modification, coupling with semiconductors, and so forth. 14 − 16 …”

One-Dimensional Multichannel g-C3N4.7 Nanostructure Realizing an Efficient Photocatalytic Hydrogen Evolution Reaction and Its Theoretical Investigations

“…These amine groups also act as a shallow electron donor whose free electron lone pairs also effectively and additionally contributed to the reduction of H + to H 2 as seen under the Computational Procedure section. 19,52 Here, more electron density is transferred to the CB of MDY from the −NH x groups as the Fermi level of the amine group is believed to lie above (more negative than) the CB of g-C 3 N 4.7 based on our current band structure experiment and reported electronic structure of liquid ammonia 53 and amine-doped graphene, 54,55 and as shown in Figure 4e (from DFT). Similar characteristics are seen in the electronic band structure of the NH 3 molecule adsorbed (ex situ doping) on a Si nanowire host material, which yields ntype doping, where the Fermi level of NH 3 found pinned near the CB of the host material.…”

Reduction of CO2 by Photoelectrochemical Process Using Non‐Oxide Two‐Dimensional Nanomaterials – A Review

“…This surface modification results in g-C 3 N 4 materials with enriched amino groups, extended light-harvesting edges, and electron transport ability, conferring good photoelectric and photocatalytic activity and selectivity. [93] Zhu et al [94] demonstrated, through DFT calculations, that CO 2 molecules preferably adsorb on the two-coordinated nitrogen atoms. Thus, nitrogen- Doping is an interesting approach to tune the electronic structure of semiconductors.…”