Template-Assisted Surface Hydrophilicity of Graphitic Carbon Nitride for Enhanced Photocatalytic H₂ Evolution

Abstract

Grafting organic groups with different electronegativities or conjugation properties on the surface of polymeric organic materials is an effective route to improving the electron structure and the charge separation. Introducing catalytic active sites on the surface of carbon nitride, such as defect creation and functional group coupling, has been developed to hinder recombination of photogenerated carriers. Herein, we report, for the first time, the fabrication of a surface-functionalized porous carbon nitride with remarkable water adsorption via a low-cost template method. By using calcium cyanamide (CaCN2) with cyano groups as a surface adjustment operator and template, the hydrophilic groups are grafted on the surface of carbon nitride. As a result, the optimized hydrogen evolution rate of macropore carbon nitride (MCN) is 4.4 times higher than that of bulk graphitic carbon nitride. The enhanced photocatalytic performance can be attributed to the formation of hydrophilic groups on the surface and the microstructural properties. This work pioneered an idea of using a promising and eco-friendly template method to tailor surface properties of carbon nitride by terminal functional groups.

Crystalline oxygen-bridged carbon nitride from self-assembled supramolecular intermediate for efficient photocatalytic H2 evolution

“…These aligned with sp 2 hybridized aromatic nitrogen (C–NC), tertiary N atoms bonded to carbon in the form of N–(C) 3 , amino groups (NH x ), and the π excitations of heterocycles or localization of positive charge. 48,49 The elevated oxygen content of 12.4% within the bulk of CMe 32 –CN, surpassing g-C 3 N 4 's 3.1%, and surface composition of 7.5%, evidenced oxygen's substitution for imido groups and its role as a bridge linking the heptazine units. Overall, the C/N ratio within CMe 32 –CN exceeded that of g-C 3 N 4 , further validating the configuration of oxygen-bridged heptazine units.…”

Cyano‐Rich g‐C3N4 in Photochemistry: Design, Applications, and Prospects

“…The template method has received much attention for its ability to synthesize porous structures to enhance the photocatalytic characteristics of carbon nitride, but further modifications can be made to prepare cyanide-modified carbon nitride materials, which broadens the application of this method in the synthesis of carbon nitride. [24,176,177] The main template agents currently used are the following: SiO 2 (relatively harmful), BaCO 3 , CaH 2 , Zn-MOFs, CaCN 2 , Halloysite, Magadiite, MgO, CaCO 3 , some of which are being used to reduce environmental hazards (Table 2). Zhang et al mixed dicyandiamide and SiO 2 in a certain ratio for self-assembly then calcined at 550 °C in nitrogen to obtain samples, and then removed the template agent by NH 4 HF 2 to obtain the final catalyst (DMCN) (Figure 10a).…”

Graphitic carbon nitride (g-C3N4) as an emerging photocatalyst for sustainable environmental applications: a comprehensive review

“…This approach enables the creation of g-C 3 N 4 materials with nely tuned properties for applications like pollutant removal and solar energy conversion. [66][67][68][69][70]…”