石墨/4H碳化硅纳米多孔阵列光阳极的制备及其光电催化性能研究

Preparation and photoelectrochemical performance of graphite/4Hsilicon carbide nanoporous array photoanodes

为提高4H碳化硅(4HSilicon carbide,4H-SiC)纳米材料的光电催化性能,采用两步阳极氧化法制备了4H-SiC纳米多孔阵列(Nanoporous array,NA),并通过高温退火制备石墨/4H-SiC NA光阳极;通过扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、高分辨多功能光谱仪和电化学工作站对石墨/4H-SiC NA光阳极的形貌、结构和性能进行了表征。结果表明:阳极氧化法能够刻蚀出纳米多孔,有效提高了4H-SiC的比表面积,同时增强了电解液与材料的接触面积;经过退火处理后,4H-SiC NA光阳极表面含有分散的石墨;在光照和暗场条件下石墨的存在增强了光生载流子的分离效果,经过优化的4H-SiC NA光阳极在光功率100mW/cm^(2)的模拟太阳光照条件下,相对于可逆氢电极(Reversible hydrogen electrode,RHE),其光电流密度在1.23V达到4.72mA/cm^(2),相比4HSiC NA光阳极提升了4.14mA/cm^(2)。该研究为提升基于4H-SiC材料的光电催化制氢性能提供了一种新思路。

To enhance the photoelectrochemical performance of 4H silicon carbide(4H-SiC)nanomaterials,a two-step anodic oxidation method was employed to prepare a 4H-SiC nanoporous array(NA).Subsequently,high-temperature annealing was applied for the fabrication of graphite/4H-SiC NA photoanodes.Then,the morphology,structure,and performance of graphite/4H-SiC NA photoanodes were characterized through scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectrometer,high-resolution multifunctional spectroscopy and an electrochemical workstation.The results indicate that anodic oxidation can etch out nano-pores,effectively increasing the specific surface area of 4H-SiC,while enhancing the contact area between the electrolyte and the material;after annealing,the surface of 4H-SiC NA photoanodes contains dispersed graphite.Under both light and dark conditions,the presence of graphite enhances the separation of photogenerated charge carriers,and the optimized 4H-SiC NA photoanodes achieve a photocurrent density of 4.72mA/cm^(2) at 1.23Vversus the reversible hydrogen electrode(RHE)under simulated solar illumination with a light power of 100 mW/cm^(2),representing an enhancement of 4.14 mA/cm^(2) compared to 4H-SiC NA photoanodes.This paper provides a new approach for improving the photoelectrochemical(PEC)hydrogen production performance based on 4H-SiC materials.