The Effects of Hydrogenation on Graphitic C₃N₄ Nanosheets for Enhanced Photocatalytic Activity

Abstract

Graphitic carbon nitride (g‐C3N4) has recently been studied as a promising metal‐free catalyst for photocatalytic hydrogen generation and environmental pollution removal. However, its photocatalytic activities are far from satisfactory, partially due to unsatisfied optical absorption and poor charge separation. Hydrogenation has recently been proven as an efficient approach in enhancing the optical absorption and improving the charge separation in oxide photocatalysts. In this study, the effects of hydrogenation on nonoxide g‐C3N4 nanosheets have been elucidated for photocatalytic applications. Hydrogenation introduces structural defects, leads to disaggregation and fragmentation, and increases the specific surface area. And it increases and redshifts the optical absorption, narrows the bandgap, and increases the donor density. The photocatalytic activities are remarkably enhanced for hydrogen production from water by 45% and pollutant removal by 650% under stimulated sunlight irradiation. The enhanced photocatalytic activity is due to the synergistic effects brought by hydrogenation: the increased optical absorption, reduced bandgap, enlarged specific surface area, and increased donor density. Thus, this study shows that hydrogenation can have a wide range of effects on the structural, optical, electronic, and photocatalytic properties of g‐C3N4, providing a facile approach to modify properties and performances of nonoxide photocatalysts.

Sugarcane juice derived carbon dot–graphitic carbon nitride composites for bisphenol A degradation under sunlight irradiation

“…However, the photocatalytic performance of bulk g-C 3 N 4 remains unsatisfactory because of the fast recombination rate of electron pairs and narrower light absorption range over the entire solar spectrum. Turning g-C 3 N 4 into a mesoporous nanorod structure [31] and the hydrogenation of g-C 3 N 4 [32] could be an alternative to increase the light-harvesting ability and charge separation efficiency. Our group has reported the self-modification of g-C 3 N 4 structures using alkaline [28] and acid treatment [29] to overcome the limitations of g-C 3 N 4 .…”

Carbon‐Coated Cu nanoparticles as a Cocatalyst of g‐C3N4 for Enhanced Photocatalytic H2 Evolution Activity under Visible‐Light Irradiation

“…It is reported that there is almost no H 2 was produced on bare g‐C 3 N 4 . The hydrogen production rate of g‐C 3 N 4 was improved by preparing g‐C 3 N 4 with various structures and morphologies, doping metal and nonmetallic atoms, loading cocatalysts, etc. The supported cocatalyst can effectively reduce the recombination of photogenerated carriers and improve the hydrogen production activity of g‐C 3 N 4 due to reduction of Schottky barrier …”

Low Temperature and Controllable Formation of Oxygen Vacancy SrTiO3‐x by Loading Pt for Enhanced Photocatalytic Hydrogen Evolution

“…[29] Meng et al found that the surface oxygen vacancy overlayer of TiO 2 can be formed via hydrogenation with Pt loading, and the surface defects are responsible for its high catalytic activity due to the suppression of electron-hole recombination. [30] Similarly, introducing oxygen vacancies or deficient by hydrogenation can enhance photocatalytic activities of TiO 2 [31] ZnO, [32] CeO 2 , [33] BiOCl, [34] g-C 3 N 4 [35] and BiPO 4 . [36] The crystal structure of SrTiO 3 is very stable because of high oxygen binding energy.…”