Experimental and computational investigation of multi-walled carbon nanotubes decorated by Co–Ni–Se@MoSe2 core–shell as a sustainable counter electrode for dye-sensitized solar cells

Abstract

The development of a highly active, long-lasting, and cost-effective electrocatalyst as an alternative to platinum (Pt) is a vital issue for the commercialization of dye-sensitized solar cells (DSSCs). Herein, Co–Ni–Se@MoSe2 core–shell structures decorated on multi-walled carbon nanotubes (MWCNTs) were synthesized for the first time by the hydrothermal and probe-sonication methods. The electrochemical performance of this composite was examined using electrochemical measurement techniques. The results showed improved properties and better electrochemical activities of the Co–Ni–Se@MoSe2@MWCNTs than Pt and other counter electrodes (CEs) for the triiodide reduction and exhibit good electrochemical stability in iodine-based electrolytes. The power conversion efficiency of DSSCs based on Co–Ni–Se@MoSe2@MWCNTs CE reaches 9.43%, significantly superior to that with Co–Ni–Se@MoSe2 core–shell (8.13%), Pt CE (7.44%), and other CEs. The notable performance is attributed to the synergistic effect between Co–Ni–Se@MoSe2 and MWCNTs. As a result, the transfer of electrons to the active site is promoted, the agglomeration of Co–Ni–Se@MoSe2 is hampered, and more active sites are available. Density functional theory calculations revealed that I2 adsorption on MoSe2 surfaces facilitated the generation of I− ions, which played a critical role in enhancing the reaction efficiency. Therefore, the Co–Ni–Se@MoSe2@MWCNTs composite is a promising candidate for use in high-performance DSSCs.