Heterojunction Bi₂Se₃/Sb₂Se₃ on Flexible Mo\nMetal Foils for Photoelectrochemical\nWater Splitting Applications

Abstract

Nanostructured heterojunctions are an effective approach\nto enhance\nthe photoelectrochemical (PEC) performance of semiconducting materials,\nas they facilitate the separation of the photogenerated charge carriers.\nHere, we report the PEC properties of the Bi₂Se₃/Sb₂Se₃ heterojunction structure on a thin\nflexible Mo metal foil. Raman spectroscopy confirmed the structural\ncomposition of Bi₂Se₃ and Sb₂Se₃ with their corresponding vibrational modes. X-ray diffraction\nshowed a rhombohedral crystal structure for Bi₂Se₃ and an orthorhombic crystal structure for Sb₂Se₃ on polycrystalline substrates. X-ray photoelectron spectroscopy\nfurther revealed the formation of Bi₂Se₃ and\nSb₂Se₃ compounds corresponding to their chemical\nand electronic states. PEC measurements were carried out under 100\nmW/cm² (AM 1.5G) simulated solar radiation in a 0.5 M Na₂SO₄ aqueous electrolyte solution and demonstrated\nan enhancement in photocurrent density from the Bi₂Se₃/Sb₂Se₃ heterojunction (127.6 μA/cm²) attributed to more active sites and easy separation of photogenerated\ncharges in comparison to bare Bi₂Se₃ (7.5 μA/cm²) and Sb₂Se₃ (76.5 μA/cm²) thin films at 0.9 V vs RHE. This preliminary study on thin metal\nfoil-based photoelectrodes paves the way toward the futuristic production\nof large-area PEC water-splitting applications.