Defect-Rich Heterogeneous MoS₂/rGO/NiS Nanocomposite for Efficient pH-Universal Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Molybdenum disulfide (MoS2) is a known electrocatalyst for the hydrogen evolution reaction (HER).
• Challenges with MoS2 include low conductivity, limited active sites, and poor stability, especially across various pH levels.
• Creating interfaces and defects using other materials can improve catalyst performance.

Purpose of the Study:

• To synthesize a defect-rich, heterogeneous ternary nanocomposite for enhanced hydrogen evolution reaction (HER) performance.
• To investigate the synergistic effects of MoS2, NiS, and reduced graphene oxide (rGO) for pH-universal catalysis.
• To develop an inexpensive and stable electrocatalyst for efficient hydrogen production.

Main Methods:

• Synthesis of a ternary nanocomposite using ultrathin αNi(OH)2 nanowires as the nickel source.
• Incorporation of MoS2, NiS, and rGO to form a defect-rich heterogeneous structure.
• Electrochemical characterization of the MoS2/rGO/NiS-5 nanocomposite in acidic, alkaline, and neutral buffer solutions.

Main Results:

• The optimal MoS2/rGO/NiS-5 formulation demonstrated low overpotentials for HER: 152 mV in H2SO4, 169 mV in KOH, and 209 mV in PBS at 10 mA cm-2.
• The enhanced performance is attributed to synergistic effects from heterogeneous interfaces, expanded interlayer spacing, and the high conductivity of rGO.
• The catalyst exhibits excellent activity and stability across a wide pH range.

Conclusions:

• The developed MoS2/rGO/NiS-5 nanocomposite is a highly effective pH-universal electrocatalyst for HER.
• The synthesis strategy offers a new approach for designing Ni-Mo heterojunction catalysts.
• This work presents a pathway towards inexpensive and stable electrocatalysts for hydrogen production.