Bi2S3 nanorods modified with Co(OH)2 ultrathin nanosheets to significantly improve its pseudocapacitance for high specific capacitance

Abstract

Nanostructured Bi₂S₃ has been used in various energy conversion and storage systems, but it alone does not possess significant capacitance and this has never been investigated. A modification at the nanoscale is used to create a structure composed of Bi₂S₃ nanorods and α-Co(OH)₂ nanosheets, which is controllably synthesized by a facile seed-layer assisted hydrothermal method to produce the former followed by electrochemical deposition of the latter. The Co(OH)₂-modified Bi₂S₃ nanorods significantly boost the pseudocapacitance of Bi₂S₃ for high specific capacitance, while improving the cycle life stability. Results reveal that the controlled Co(OH)₂ modification process promotes a networked, highly porous structure for a considerably larger surface allowing the electrolyte-access; thus, enhancing the pseudocapacitance and resulting in a high specific capacitance.