碳纳米管改性g-C3N4提升可见光催化降解性能

以尿素为原料,引入少量的多壁碳纳米管(CNT)改性,采用简便方法制备CNT/g-C_3N_4催化剂。利用扫描电镜(SEM)、透射电镜(TEM)、傅里叶红外光谱仪(FT-IR)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见-近红外分光光度计(UV-Vis-NIR Spectrophotometer)、荧光光谱(PL)等手段对CNT/g-C_3N_4催化剂进行表征。结果表明,g-C_3N_4与CNT之间的协同作用,影响了gC_3N_4的能带结构,增强了其对可见光的吸收,改善了光生载流子的分布,提高了电子-空穴对的分离效率。并以罗丹明B(RhB)水溶液模拟废水,在可见光下考察催化剂的光催化降解性能,发现当CNT掺杂量为0.1%(w/w)时效果最佳,降解速率常数是体相g-C_3N_4的3.1倍,且研究发现超氧自由基是该体系下的主要活性物种。

Synthesis of Carbon Nanotubes Modified g-C3N4 Photocatalysts for Enhanced Photocatalytic Degradation Activity

Graphitic carbon nitride hybridized with a small number of carbon nanotubes (CNT) was synthesized using urea as precursor. The resulting CNT/g-C₃N₄ composite photocatalysts were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier infrared spectrometer (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible-near infrared Reflection Spectrophotometer (UV-Vis-NIR Spectrophotometer) and photoluminescence spectroscopy (PL). Results indicate that the synergistic interaction between CNT and g-C₃N₄ changed the optical properties of bulk g-C₃N₄, affected the energy band structure, enhanced the absorption of visible light, optimized the distribution of the photogenerated carrier and improved the electron-hole separation rate. The photocatalytic degradation of rhodamine B solution (RhB) was performed under visible light irradiation. The photocatalytic activity of CNT/g-C₃N₄ composite was the highest when 0.1%(w/w) CNT was loaded on the substrate, the rate constant for the photocatalyst was 3.1 times as high as that of pure g-C₃N₄. It was also found that the superoxide radical was the main active species for catalytic degradation in this system.