Activation of basal-plane sulfur sites on MoS₂ @Ni₃S₂ nanorods by Zr plasma ion implantation for bifunctional electrocatalysts

Water electrolysis is one of the most promising technologies for sustainable and clean energy production, yet the sluggish kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) hampers the commercialization. In this work, Zr-doped MoS₂ @Ni₃S₂ (MSNF) heterogeneous nanorods as bifunctional electrocatalysts were successfully explored to boost the catalytic activity of water electrolysis. The structural characterizations demonstrate the uniform modification of Zr atoms on the basal plane of MoS₂ at the heterointerface of MSNF. MSNF implanted with a Zr plasma ion fluence of 5 × 10¹⁶ ions-cm⁻² (Zr500-MSNF) shows the most remarkable bifunctional electrocatalytic characteristics such as Tafel slope of 60.9 mV dec⁻¹ and overpotential of 98 mV at 10 mA cm⁻² for HER, as well as Tafel slope of 78.5 mV dec⁻¹ and overpotential of 275 mV at 20 mA cm⁻² for OER. Consistent with the structural and electrocatalytic characterizations, first-principles calculation confirms that the activated S sites in the basal plane of MoS₂ upon Zr doping have more empty states in its valence orbital to favor the adsorption of hydrogen and hydroxide, thus contributing to enhanced HER and OER activity. The findings in this work reveal a facile strategy to design high-performance and low-cost bifunctional catalysts based on two-dimensional materials for overall water splitting. © 2023 Elsevier B.V.