Engineering Amorphous/Crystalline Rod-like Core-Shell Electrocatalysts for Overall Water Splitting.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Designing bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with high activity and stability is crucial for water splitting.
• Existing catalysts often face challenges in achieving both high performance and long-term durability.

Purpose of the Study:

• To develop a novel amorphous ruthenium dioxide-encapsulated crystalline nickel selenide nanorod structure (a/c-RuO2/Ni0.85Se) as a bifunctional electrocatalyst.
• To enhance both hydrogen and oxygen evolution reaction activities and overall water splitting performance.
• To investigate the theoretical mechanism behind the enhanced HER activity.

Main Methods:

• Synthesis of amorphous RuO2-encapsulated crystalline Ni0.85Se nanorods.
• Electrochemical characterization for HER, OER, and overall water splitting performance.
• Long-term stability testing of the electrocatalyst.
• Density functional theory (DFT) calculations to analyze the electronic structure and adsorption properties.

Main Results:

• The a/c-RuO2/Ni0.85Se nanorods exhibited excellent HER activity (58 mV@10 mA cm-2) and OER activity (233 mV@10 mA cm-2).
• The catalyst demonstrated superior overall water splitting performance with an applied voltage of 1.488 V at 10 mA cm-2.
• The bifunctional electrocatalyst showed remarkable long-term stability, with negligible performance decay after 50 hours of continuous operation.
• DFT calculations revealed that the coupling of amorphous RuO2 layers modifies the d-band center, enhancing hydrogen species adsorption for improved HER activity.

Conclusions:

• The developed a/c-RuO2/Ni0.85Se nanostructure serves as a highly effective bifunctional electrocatalyst for water splitting.
• The synergistic effect between amorphous RuO2 and crystalline Ni0.85Se contributes to the enhanced catalytic performance and stability.
• This study presents a promising strategy for fabricating advanced electrocatalysts for efficient green hydrogen production.