纳米Ti_(3)C_(2)/g-C_(3)N_(4)光催化剂的制备与高效降解亚甲基蓝

Preparation of nanoTi_(3)C_(2)/g-C_(3)N_(4)photocatalyst and its efficient degradation of methylene blue

通过一步水热法将纳米Ti_(3)C_(2)原位氧化为TiO_(2)量子点−碳量子点,并将其作为助催化剂包覆于g-C_(3)N_(4)基底上。通过表征复合光催化剂的物相组成、表面化学态和显微形貌,确定纳米Ti_(3)C_(2)成功转化为TiO_(2)量子点−碳量子点,并且均匀分布于g-C_(3)N_(4)基底表面。在制备过程中,当纳米Ti_(3)C_(2)加入量为60 mg时,该复合光催化剂展现出最高的催化效率,是单一g-C_(3)N_(4)的4.37倍。光电化学测试和第一性原理计算结果表明,该催化效率提升的主要原因为TiO2量子点与g-C_(3)N_(4)形成了结合紧密的type Ⅱ型异质结,从而提高了光生载流子的分离和迁移效率。同时,碳量子点(CQDs)的上转换效应将600~750 nm波长范围的光转化为g-C_(3)N_(4)可吸收的400~460 nm的可见光,提高了g-C_(3)N_(4)对太阳光的利用率。该研究为异质光催化剂的制备和性能提升提供了新的研究思路和方法借鉴。

Using simple hydrothermal method,Ti_(3)C_(2)nanoparticles were in situ oxidized into TiO_(2)quantum dots-carbon quantum dots(TiO_(2)QDs-CQDs)and coated onto the surface of g-C_(3)N_(4)as a co-catalyst.The phase composition,surface chemical states and microstructure of the composite photocatalyst were characterized,which confirms that Ti_(3)C_(2)is successfully transformed into TiO_(2)QDs-CQDs and uniformly distributes on the surface of g-C_(3)N_(4).During the preparation process,the composite photocatalyst exhibits the highest catalytic efficiency when the amount of Ti_(3)C_(2)added is 60 mg,which is 4.37 times higher than that of pure g-C_(3)N_(4).The results of the photoelectrochemical tests and first-principles calculations show that the main reason for the improved catalytic efficiency is the formation of closely combined type Ⅱ heterojunction between TiO_(2)QDs and g-C_(3)N_(4),which increases the separation and migration efficiency of photogenerated carriers.In addition,the upconversion effect of carbon quantum dots(CQDs)converts light in the wavelength range of 600−750 nm into visible light of 400−460 nm,which can be absorbed by g-C_(3)N_(4),thereby increasing the utilization of solar light by g-C_(3)N_(4).This study provides new research ideas and methods for the preparation and performance improvement of heterojunction photocatalysts.