TiO_(2)@H^(+)/g⁃C_(3)N_(4)复合材料的光催化产氢性能及机理分析

Photocatalytic Hydrogen Production Properties and Mechanism Analysis of TiO_(2)@H^(+)/g⁃C_(3)N_(4)Composites

本文研究了TiO_(2)含量对TiO_(2)@H^(+)/g-C_(3)N_(4)异质结光催化剂产氢性能的影响。首先将石墨相氮化碳(g-C_(3)N_(4))用硫酸处理,得到酸洗氮化碳(H^(+)/g-C_(3)N_(4)),然后通过煅烧法在H^(+)/g-C_(3)N_(4)表面负载TiO_(2)得到TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料,利用透射电镜、X射线衍射仪、紫外-可见漫反射仪和比表面仪对TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料进行了表征,研究了其在可见光下的光催化产氢性能,探讨了TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料光催化产氢机理。实验结果表明:1)煅烧法可以成功制备TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料,且TiO_(2)的负载显著地提升了H^(+)/g-C_(3)N_(4)的光催化产氢性能,这主要归功于TiO_(2)/g-C_(3)N_(4)异质结的形成降低了光生电子空穴的复合速率,加快了电子的转移速率;2)实验结果还表明TiO_(2)的负载量对TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料的光催化产氢性能有很大影响,当TiO_(2)含量为25%时,所制备的25-TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料的光催化产氢性能最好,其光催化产氢速率为3.47 mmol·g^(−1)·h^(−1),是H^(+)/g-C_(3)N_(4)产氢速率的4.05倍,这主要归功于25-TiO_(2)@H^(+)/g-C_(3)N_(4)大的比表面积和高的光吸收度;3)所制备的25-TiO_(2)@H^(+)/g-C_(3)N_(4)复合材料还表现出良好的稳定性。

The influence of the loading amount of TiO_(2)on the photocatalytic H2 production performance of TiO_(2)@H^(+)/g-C_(3)N_(4)composites were studied.Graphite phase carbon nitride(g-C_(3)N_(4))was first treated with sulfuric acid to obtain pickled carbon nitride(H^(+)/g-C_(3)N_(4)),and then TiO_(2)@H^(+)/g-C_(3)N_(4)composites were prepared by loading TiO_(2)on the surface of H^(+)/g-C_(3)N_(4)by calcination method.The photocatalytic hydrogen production of TiO_(2)@H^(+)/g-C_(3)N_(4)composite was characterized by transmission electron microscopy,X-ray diffractometer,UV-vis diffractometer and specific surface analyzer.The photocatalytic performances of H2 production of TiO_(2)@H^(+)/g-C_(3)N_(4)composites were investigated under the irradiation of visible light.The photocatalytic hydrogen production mechanism of TiO_(2)@H^(+)/g-C_(3)N_(4)composite was discussed.The results show that the TiO_(2)@H^(+)/g-C_(3)N_(4)composites are synthesized by calcination.The photocatalytic property of H^(+)/g-C_(3)N_(4)is increased by the loading of TiO_(2),which is due to the separation promotion of the photogenerated electron-hole pairs and the acceleration of the electrons transfer rate by TiO_(2)/g-C_(3)N_(4)heterojunctions.Moreover,the loading amount of TiO_(2)has great effects on the photocatalytic H2 production performance of TiO_(2)@H^(+)/g-C_(3)N_(4)composites.With TiO_(2)loading of 25%,the photocatalytic H2 production rate of the prepared 25-TiO_(2)@H^(+)/g-C_(3)N_(4)composite is the highest,which is 3.47 mmol·g^(−1)·h^(−1)and about 4.05 times of that of H^(+)/g-C_(3)N_(4).This good property is attributed to the large specific surface area and high absorbance of 25-TiO_(2)@H^(+)/g-C_(3)N_(4)composite.Moreover,the prepared 25-TiO_(2)@H^(+)/g-C_(3)N_(4)composites show good stability in the process of photocatalytic H2 production.