Design and fabrication of Ni-Mn-Co sulfides@NiCo2S4 structure anchored on nitrogen-doped carbon nanotubes as a sufficient and promising counter electrode for high-efficiency dye-sensitized solar cells

Inexpensive electrocatalysts with excellent catalytic activity as the counter electrodes (CEs) are crucial for the commercialization of solar cells. In this study, the Ni-Mn-Co sulfides@NiCo 2 S 4 structures are constructed and anchored on nitrogen-doped carbon nanotubes (Ni-Mn-Co sulfides@NiCo 2 S 4 /N-CNTs) via hydrothermal and sonication methods. This catalyst is applied as CE in a dye-sensitized solar cells (DSSC). The results exhibit better electrochemical activities and improved properties of the Ni-Mn-Co sulfides@NiCo 2 S 4 /N-CNTs compared to platinum (Pt) and other CEs toward the triiodide reduction. Consequently, solar cells constructed with Ni-Mn-Co sulfides@NiCo 2 S 4 /N-CNTs provide an impressive power conversion efficiency of 9.18 %, which is superior to that of Pt-based devices (6.81 %). This robust behavior is mainly attributed to the positive synergistic effect between Ni-Mn-Co sulfides and NiCo 2 S 4 , large specific surface area and the excellent conductivity of N-CNTs, and the coupling effect between N-CNTs and Ni-Mn-Co sulfides@NiCo 2 S 4 structure. The results of the computational study show the low HOMO-LUMO bandgap for Ni-Mn-Co sulfides@NiCo 2 S 4 /N-CNTs which suggests that by decoration of Ni-Mn-Co sulfides@NiCo 2 S 4 on N-CNTs, the electron transfer can be facilitated. The current study leads towards designing highly efficient and cost-effective multifunctional electrocatalysts for advanced energy conversion technologies. • Ni-Mn-Co sulfides@NiCo 2 S 4 /N-CNTs is created by simple method. • Catalyst shows good catalytic activity and stability. • DSSC with this catalyst achieves a high PCE of 9.18 %. • N-CNTs increase active sites and improve efficiency.