SiC/Pt/CdS纳米棒Z型异质结的制备及其高效光催化产氢性能

Fabrication of Z-Scheme Heterojunction of Si C/Pt/Cds Nanorod for Efficient Photocatalytic H2 Evolution

本文采用简单的化学还原辅助水热法制备了一种新型Si C/Pt/Cd SZ型异质结纳米棒,并将Pt纳米粒子锚定在Si C纳米棒与Cd S纳米粒子的界面间,诱导电子-空穴对沿着Z型迁移路径进行转移。进行一系列的表征来分析该催化体系的结构,形貌和性能。X射线衍射(XRD)和X射线光电子能谱(XPS)结果表明,成功合成了具有较好晶体结构的光催化剂。通过透射电子显微镜证明,Pt纳米颗粒生长在Si C纳米棒和Cd S纳米颗粒的界面间。UV-Vis漫反射光谱显示,所制备的Z-型异质结样品具有比原始Cd S材料更宽的光吸收范围。光致发光光谱和瞬态光电流响应进一步证明具有最佳摩尔比的Si C/Pt/Cd S纳米棒样品具有最高的电子-空穴对分离效率。通过控制Si C和Cd S的摩尔比,可以有效地调节Si C/Pt纳米棒表面Cd S的负载量,从而使得Si C/Pt/Cd S纳米棒光催化剂达到最佳性能。当Si C:Cd S=5:1(摩尔比)时可以达到最佳产氢性能,其最大析氢速率达到122.3μmol·h-1。此外,从扫描电子显微镜、XRD和XPS分析可以看出,经过三次循环测试后,Si C/Pt/Cd S光催化剂的形貌和晶体结构均基本保持不变,表明Si C/Pt/Cd S纳米复合材料在可见光下产氢时具有稳定的结构。通过选择性光沉积技术在光反应中同时进行Au纳米粒子的光还原沉积和Mn3O4纳米粒子光氧化沉积以证明电子-空穴对的Z-型转移机制。实验结果表明,Cd S导带上的电子主要参与光催化过程中的还原反应,Si C价带上的空穴更容易发生氧化反应,其中,Si C的导带上的电子将与Cd S价带上的空穴复合形成Z型传输路径。因此,提出了在光催化产氢过程中Si C/Pt/Cd S纳米棒催化体系可能的Z-型电荷迁移路径来解释产氢活性的提高。该研究为基于Si C纳米棒的Z-型光催化体系的合成提供了新的策略。基于以上分析,Si C/Pt/Cd S纳米复合材料具有高效、廉价、易于制备、结构稳定等优势,具有突出的商业应用前景。

In this study,a novel silicon carbide/platinum/cadmium sulfide(Si C/Pt/Cd S)Z-scheme heterojunction nanorod is constructed using a simple chemical reduction-assisted hydrothermal method,in which Pt nanoparticles are anchored at the interface of Si C nanorods and Cd S nanoparticles to induce an electron-hole pair transfer along the Z-scheme transport path.Multiple characterization techniques are used to analyze the structure,morphology,and properties of these materials.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)results show that the Si C/Pt/Cd S materials with good crystalstructure are successfully synthesized.Transmission electron microscopy reveals that Pt nanoparticles grow between the interfaces of Si C nanorods and Cd S nanoparticles.UV-Vis diffuse reflectance spectroscopy shows that the as-prepared Zscheme heterojunction samples have a wider light absorption range in comparison with pristine Cd S materials.Photoluminescence spectroscopy and the transient photocurrent response further demonstrate that the Si C/Pt/Cd S nanorod sample with an optimal molar ratio possesses the highest electron-hole pair separation efficiency.The loading amount of Cd S on the surface of Si C/Pt nanorods is effectively adjusted by controlling the molar ratio of Si C and Cd S to achieve the optimal performance of the Si C/Pt/Cd S nanorod photocatalysts.The optimal H2 evolution capacity is achieved at Si C:Cd S=5:1(molar ratio)and the maximum H2 evolution rate reaches a high value of 122.3μmol·h-1.In addition,scanning electron microscopy,XRD,and XPS analyses show that the morphology and crystal structure of the Si C/Pt/Cd S photocatalyst remain unchanged after three cycles of activity testing,indicating that the Si C/Pt/Cd S nanocomposite has a stable structure for H2 evolution under visible light.To prove the Z-scheme transfer mechanism of electron-hole pairs,selective photo-deposition technology is used to simultaneously carry out the photo-reduction deposition of Au nanoparticles and photo-oxidation deposition of Mn3 O4 nanoparticles in the photoreaction.The experimental results indicate that during photocatalysis,the electrons in the conduction band of Cd S participate mainly in the reduction reaction,and the holes in the valence band of Si C are more likely to undergo the oxidation reaction.The electrons in the conduction band of Si C combine with the holes in the valence band of Cd S to form a Z-scheme transport path.Therefore,a possible Z-scheme charge migration path in Si C/Pt/Cd S nanorods during photocatalytic H2 production is proposed to explain the enhancement in the activity.This study provides a new strategy for synthesizing a Z-scheme photocatalytic system based on Si C nanorods.Based on the characterization results,it is determined that Si C/Pt/Cd S nanocomposites are highly efficient,inexpensive,easy to prepare,and are stable structures for H2 evolution under visible light with outstanding commercial application prospects.