Exploring the synergistic effect of NixSn2xS4x thiospinel with MWCNTs for enhanced performance in dye-sensitized solar cells, the hydrogen evolution reaction, and supercapacitors

Abstract

Trifunctional nickel tin sulfide (Ni_xSn_2xS_4x) with a thiospinel-like structure composited with multiwalled carbon nanotubes (MWCNTs) (M–Ni_xSn_2xS_4x) was synthesized by a facile method. The unit cell arrangement of the prepared composite was studied by density functional theory, and the theoretical interpretation satisfactorily inferred the presence of a synergistic effect between the thiospinel and MWCNTs. The high metallic conductivity and superior electrocatalytic activity of the M–Ni_xSn_2xS_4x composite endow it with diverse applications. The composite shows promise as a counter electrode for dye-sensitized solar cells (efficiency of 4.67% for fluorine-doped indium tin oxide compared to 5.23% for platinum); an efficient catalyst for the hydrogen evolution reaction with good cycling stability and a low overpotential of −41 mV at a cathode current density of 10 mA cm² and a Tafel slope of 43 mV dec⁻¹ on a graphite sheet electrode; and an impressive capacitance material on a graphite sheet electrode alternative to expensive current collectors such as Ni foam, with a specific capacitance value of 1200 F g⁻¹ at a current density of 1 A g⁻¹ and a long life span of 92.6% that is retained for up to 15 000 cycles.