Electrospun and hydrothermal techniques to synthesize the carbon-coated nickel sulfide microspheres/carbon nanofibers nanocomposite for high performance liquid-state solar cells

Abstract

To achieve optimal electrochemical performance, a highly efficient and stable noble-metal-free catalyst which consists of carbon-coated nickel sulfide microspheres (Ni3S4@C) and carbon nanofibers (CNFs) are synthesized through the electrospinning and hydrothermal method. The optimized sample provides a large amount of active sites that benefit electron transfer which is further applied as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). A series of electrochemical measurements reveal that the resultant Ni3S4@C/CNFs show higher catalytic activity toward the reduction of I3− to I− in comparison to the benchmark Pt, Ni3S4@C, pure Ni3S4 and CNFs. As a result, the DSSC device assembled with Ni3S4@C/CNFs-based CE affords a decent power conversion efficiency (PCE) of 8.29%, which surpasses the corresponding values of the device using the commercial Pt (7.35%), Ni3S4@C(6.81%), pure Ni3S4(6.51%) and CNFs (6.11%) CE under identical conditions. This work unfolds a new strategy for developing low-cost and effective CE materials in DSSCs.