Heterojunction Bi<sub>2</sub>Se<sub>3</sub>/Sb<sub>2</sub>Se<sub>3</sub> on Flexible Mo Metal Foils for Photoelectrochemical Water Splitting Applications
Bheem Singh, Sudhanshu Gautam, Vishnu Aggarwal, Govinda Chandra Behera, Nasima Khatun, Rahul Kumar, J.S. Tawale, Ramakrishnan Ganesan, Somnath C. Roy, Vidya Nand Singh, Sunil Singh Kushvaha
Abstract
Nanostructured heterojunctions are an effective approach to enhance the photoelectrochemical (PEC) performance of semiconducting materials, as they facilitate the separation of the photogenerated charge carriers. Here, we report the PEC properties of the Bi 2 Se 3 /Sb 2 Se 3 heterojunction structure on a thin flexible Mo metal foil. Raman spectroscopy confirmed the structural composition of Bi 2 Se 3 and Sb 2 Se 3 with their corresponding vibrational modes. X-ray diffraction showed a rhombohedral crystal structure for Bi 2 Se 3 and an orthorhombic crystal structure for Sb 2 Se 3 on polycrystalline substrates. X-ray photoelectron spectroscopy further revealed the formation of Bi 2 Se 3 and Sb 2 Se 3 compounds corresponding to their chemical and electronic states. PEC measurements were carried out under 100 mW/cm 2 (AM 1.5G) simulated solar radiation in a 0.5 M Na 2 SO 4 aqueous electrolyte solution and demonstrated an enhancement in photocurrent density from the Bi 2 Se 3 /Sb 2 Se 3 heterojunction (127.6 μA/cm 2 ) attributed to more active sites and easy separation of photogenerated charges in comparison to bare Bi 2 Se 3 (7.5 μA/cm 2 ) and Sb 2 Se 3 (76.5 μA/cm 2 ) thin films at 0.9 V vs RHE. This preliminary study on thin metal foil-based photoelectrodes paves the way toward the futuristic production of large-area PEC water-splitting applications.