School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, People's Republic of China.
Nanotechnology. 2019 Aug 2;30(31):315601. doi: 10.1088/1361-6528/ab10fd. Epub 2019 Mar 19.
Modified g-CN samples (g-X, where X corresponds to the number of hours of acid treatment of the melamine) with outstanding photocatalytic performance were prepared by using hydrochloric acid-treated melamine as a precursor and calcining at 550 °C for 2 h. An x-ray diffractometer, field-emission scanning electron microscope, infrared spectrometer, N adsorption-desorption test, x-ray photoelectron spectroscopy, and ultraviolet-visible diffuse-reflectance spectroscopy analysis were carried out to characterize the phase composition, microstructure, chemical structure, specific surface area (SSA), chemical states, elemental composition and optical properties of the samples, respectively. The photocatalytic performance of the samples was evaluated by degrading the Rhodamine B (RhB) aqueous solution. The results showed that the crystal structure and vibration bands of melamine changed due to the reaction with hydrochloric acid. The crystallinity and grain size of g-CN in g-X (X = 1, 2, 4, 6, 8, 10) reduced, and the SSA values of g-X increased compared to that of the g-0 sample, which was synthesized from pristine melamine. The g-X samples exhibited excellent photocatalytic activity towards degradation of RhB compared to g-0. The photocatalytic activity of the g-X samples increased gradually as the acid treatment time of the melamine increased from 1 h to 2 h, and then decreased gradually with the extension of the acid treatment time. The rate constant (k) values of g-X are higher than that of g-0. g-2 presented the highest rate constant (k = 0.052 min), which was 5.5 times higher than that of g-0. The improved photocatalytic activity of the g-X samples was attributed to the higher SSA value, the appearance of surface defects, the outstanding photo-carrier separation efficiency and stronger light harvesting ability of g-X, with the last two factors being more significant. Acid treatment of melamine is helpful in the preparation of high performance g-CN photocatalyst, and the microstructure and photocatalytic performance of g-CN were affected significantly by the acid treatment time.
采用盐酸处理过的三聚氰胺作为前驱体，在 550°C 下煅烧 2 h，制备出具有优异光催化性能的改性 g-CN 样品（g-X，其中 X 对应于三聚氰胺酸处理的小时数）。采用 X 射线衍射仪、场发射扫描电子显微镜、红外光谱仪、N2 吸附-脱附测试、X 射线光电子能谱和紫外-可见漫反射光谱分析，分别对样品的物相组成、微观结构、化学结构、比表面积（SSA）、化学态、元素组成和光学性能进行了表征。通过降解罗丹明 B（RhB）水溶液评价了样品的光催化性能。结果表明，由于与盐酸的反应，三聚氰胺的晶体结构和振动带发生了变化。与由原始三聚氰胺合成的 g-0 相比，g-X（X=1、2、4、6、8、10）中 g-CN 的结晶度和晶粒尺寸降低，SSA 值增加。与 g-0 相比，g-X 样品对 RhB 的降解具有优异的光催化活性。随着三聚氰胺酸处理时间从 1 h 增加到 2 h，g-X 样品的光催化活性逐渐增加，然后随着酸处理时间的延长逐渐降低。g-X 样品的速率常数（k）值高于 g-0。g-2 表现出最高的速率常数（k=0.052 min），比 g-0 高 5.5 倍。g-X 样品光催化活性的提高归因于更高的 SSA 值、表面缺陷的出现、出色的光载流子分离效率和更强的光捕获能力，后两个因素更为显著。三聚氰胺的酸处理有助于制备高性能 g-CN 光催化剂，g-CN 的微观结构和光催化性能受酸处理时间的影响显著。
