Strong Interface Coupling Enables Stability of Amorphous Meta-Stable State in CoS/Ni₃S₂ for Efficient Oxygen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Rational design of heterostructure catalysts is crucial for improving electrocatalytic performance.
• Phase engineering is a key strategy for developing advanced catalysts.
• Amorphous/crystalline (a/c) heterostructures offer unique properties compared to crystalline/crystalline counterparts.

Purpose of the Study:

• To synthesize a novel amorphous/crystalline heterostructure catalyst (a-CoS/Ni3S2) using a facile hydrothermal sulfurization method.
• To investigate the impact of amorphous phase presence on catalyst stability, sulfur vacancies, and electrocatalytic activity.
• To understand the charge transfer dynamics and catalytic mechanism in a/c heterostructures for the oxygen evolution reaction (OER).

Main Methods:

• Facile hydrothermal sulfurization method for synthesizing a-CoS/Ni3S2.
• Electrochemical characterization, including OER performance testing (overpotential, current density).
• Fabrication of an electrocatalytic cell for overall water splitting.
• Theoretical calculations (e.g., DFT) to elucidate charge transfer mechanisms.

Main Results:

• The a-CoS/Ni3S2 heterostructure exhibited stronger interface coupling and enhanced stability compared to the crystalline control (c-CoS/Ni3S2).
• The a-CoS/Ni3S2 material displayed a significantly lower OER overpotential (192 mV at 10 mA cm-2) than c-CoS/Ni3S2 (242 mV).
• An assembled water-splitting cell using a-CoS/Ni3S2 achieved a low cell voltage of 1.51 V at 50 mA cm-2.

Conclusions:

• The amorphous/crystalline heterostructure strategy effectively enhances electrocatalytic activity for OER.
• The enhanced performance is attributed to improved interface coupling, increased sulfur vacancies, and favorable charge transfer.
• This work provides a valuable fabrication strategy for a/c catalysts and deepens the understanding of their catalytic mechanisms.