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In this contribution, the effect of hydrogenation conditions atmosphere (temperature and time) on physicochemical properties and photocatalytic efficiency of graphitic carbon nitride (g-C3N4, gCN) was studied in great details. The changes in the morphology, chemical structure, optical and electrochemical properties were carefully investigated. Interestingly, the as-modified samples exhibited boosted photocatalytic degradation of Rhodamine B (RhB) with the assistance of visible light irradiation. Among modified gCN, the sample annealed at 500 °C for 4 h (500-4) in H2 atmosphere exhibited the highest photocatalytic activity—1.76 times higher compared to pristine gCN. Additionally, this sample presented high stability and durability after four cycles. It was noticed that treating gCN with hydrogen at elevated temperatures caused the creation of nitrogen vacancies on gCN surfaces acting as highly active sites enhancing the specific surface area and improving the mobility of photogenerated charge carriers leading to accelerating the photocatalytic activity. Therefore, it is believed that detailed optimization of thermal treatment in a hydrogen atmosphere is a facile approach to boost the photoactivity of gCN. [ABSTRACT FROM AUTHOR]

Spherical photocatalyst based on ordered mesoporous carbon and graphitic carbon nitride with core/shell structure (CS/GCN) was successfully synthesized via facile electrostatic self-assembly strategy. The photocatalytic properties of the hybrid were evaluated by the decomposition of Acid Red 18 under simulated solar light irradiation in comparison to the bulk graphitic carbon nitride (GCN). The results clearly revealed that coupling of carbon nitride with mesoporous carbon allows the catalyst to form with superior photocatalytic performance. The photoactivity of CS/GCN was over nine times higher than that of pristine GCN. Introducing mesoporous carbon into GCN induced higher surface area of the heterojunction and also facilitated the contact surface between the two phases. The synergistic effect between those two components enhanced the visible light-harvesting efficiency and improved photoinduced charge carrier generation, and consequently their proper separation. The electrochemical behavior of the obtained composite was also evaluated by electrochemical impedance, transient photocurrent response and linear sweep potentiometry measurements. The results confirmed that transport and separation of charge carriers in the hybrid was enhanced in comparison to the reference bulk graphitic carbon nitride. Detailed electrochemical, photoluminescence and radical scavenger tests enabled determination of the possible mechanism of photocatalytic process. This work presents new insights to design a core/shell hybrid through the simple preparation process, which can be successfully used as an efficient photocatalyst for the treatment of wastewater containing dyes under solar light irradiation. [ABSTRACT FROM AUTHOR]