Abstract Two types of bulk graphitic carbon nitrides (CN) were synthetized by heating melamine at 550 °C for 4 h in the air (CN/air) and nitrogen (CN/N2) atmosphere for us to find the effect of present oxygen on their properties. Bulk CN was exfoliated by further heating at 500 °C for 1–3 h in air and nitrogen as well. The obtained materials were studied in terms of structural, textural and physico-chemical properties including photocatalytic activity. The CN/air materials contained less oxygen (2.3–5.0 wt%) than the CN/N2 ones (about 7 wt%) due to decarboxylation during their synthesis and exfoliation in air. The CN/N2 materials had more structural defects, which were attacked by oxygen from the moment the materials came into contact with air. In both types of materials oxygen was supposed to be present mostly in the form of hydroxyl groups. As a result, the CN/N2 materials were slightly exfoliated and their surfaces were more hydrophilic than the CN/air ones. The photocatalytic activity of CN materials was dependent on their specific surface area (SSA). It was found that native oxygen existed in the CN materials and was important for their properties.

中文翻译：

---

空气和氮气气氛下合成的石墨氮化碳中氧的存在及影响

摘要 通过在空气 (CN/air) 和氮气 (CN/N2) 气氛中将三聚氰胺在 550 °C 下加热 4 h 合成了两种类型的块状石墨氮化碳 (CN)，以研究当前氧气对其的影响。特性。通过在空气和氮气中在 500°C 下进一步加热 1-3 小时，散装 CN 被剥离。研究了所得材料的结构、质地和物理化学性质，包括光催化活性。由于在合成过程中脱羧和在空气中剥离，CN/空气材料比 CN/N2 材料（约 7wt%）含有更少的氧气（2.3-5.0 wt%）。CN/N2 材料具有更多的结构缺陷，从材料与空气接触的那一刻起，这些缺陷就会受到氧气的攻击。在这两种类型的材料中，氧主要以羟基的形式存在。结果，CN/N2 材料轻微剥落，其表面比 CN/空气材料更亲水。CN 材料的光催化活性取决于它们的比表面积 (SSA)。发现天然氧存在于 CN 材料中，并且对其性能很重要。