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In this paper, a novel pristine carbon nitride (np-CN) with hollow capsule-like morphology was facilely prepared by the thermal polymerization of melamine and cyanuric chloride at 550 1C in air for 4 h. Then, modified carbon nitride (CN-P4mg) micro-flakes with zigzag edges were synthesized by the copolymerization of melamine, cyanuric chloride, and triaminotriphenylamine with a mass fraction of 0.13%. Analysis of the microstructure, surface state, porosity, and optoelectronic properties of the two samples indicates that CN-P4mg has a larger specific surface area and a lower bandgap than np-CN. Under visible light, CN-P4mg displays enhanced photocatalytic performance for the generation of hydrogen compared to that of np-CN and bulk graphite carbon nitride (g-C3N4). The photocatalytic hydrogen evolution rate of CN-P4mg reaches 16897.3 mmol g-1 h-1, which is 1.84 times that of np-CN and 72 times that of bulk g-C3N4. The experimental results confirm that the addition of triaminotriphenylamine provides a modified design for developing metal-free carbon nitride derivatives and a new route to study efficient photocatalytic materials. [ABSTRACT FROM AUTHOR]

Graphite carbon nitride (g-C3N4) has attracted much attention in the field of photocatalysis because of its visible light response and stable properties. However, its photocatalytic activity is not ideal because of its limited visible light response range, easy recombination of photogenerated electron holes, and poor dispersion. In this study, the visible light catalytic performance of g-C3N4 was significantly improved by the double modification method of surface hydroxyl and coupling agent grafting. Firstly, g-C3N4 was prepared by thermal polymerization with melamine as the raw material, and then the surface hydroxyl group was introduced by hydrogen peroxide. Finally, the organic groups were grafted on the surface of g-C3N4 by using silane coupling agent YDH171 as the grafting agent. The catalysts were characterized by FT-IR, XPS, XRD, contact angle measurements, UV-vis DRS, PL, electrochemical methods and particle size distribution. Taking simulated oily wastewater as the target material, the reaction rate of graphite carbon nitride was increased by 2.7 times after surface double modification. Moreover, a radical trap experiment was carried out, which indicated that the hole acted as the main reactive species for the photocatalytic degradation process. The catalytic mechanism of the material was investigated. The results showed that the synergistic effect of surface hydroxyl group grafting and coupling agent grafting increased the separation efficiency of photogenerated electron holes and improves their dispersion in water, thus promoting the photocatalytic performance of the catalyst. [ABSTRACT FROM AUTHOR]