Preparation and photoelectrochemical performance of graphite/4H silicon carbide nanoporous array photoanodes
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 4.72 mA/cm2 at 1.23 V versus the reversible hydrogen electrode(RHE)under simulated solar illumination with a light power of 100 mW/cm2,representing an enhancement of 4.14 mA/cm2 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.