Boosting hydrogen evolution and triiodide reduction via electronic coupling on a (1T, 2H) MoS2@N-doped carbon dodecahedron†

Abstract

Designing a noble-metal-free catalyst with the desired composition and structure is highly significant for accelerating the catalytic kinetics of the hydrogen evolution reaction (HER) and triiodide reduction reaction (IRR), which is essential for advancing green hydrogen production from water electrolysis and improving the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Herein, small-sized (1T, 2H) phase MoS₂ nanosheets were uniformly wrapped around an N-doped C dodecahedron (MoS₂@NC) through a continuous synthesis strategy with ZIF-8 serving as the original template. When MoS₂@NC is used as a catalyst for the HER, it only requires a low overpotential of 93 mV to reach 10 mA cm⁻², surpassing most reported MoS₂-based catalysts. Furthermore, a device fabricated with MoS₂@NC achieves a PCE of 8.20%, which is comparable to that of a Pt-based one (8.59%). Theoretical calculations revealed that the enhanced HER activity of MoS₂@NC is mainly attributed to the enhanced water adsorption energy and a reduced energy barrier for overcoming the rate-determining step during the HER process. Additionally, the interfacial S sites in MoS₂@NC are responsible for the excellent catalytic activity in the IRR. The experimental and theoretical results collectively confirm that the as-designed MoS₂@NC is a promising bifunctional catalyst.