Ruthenium-Alloyed Iron Phosphide Single Crystal with Increased Fermi Level for Efficient Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Alloying transition metal phosphides is key to improving hydrogen evolution reaction (HER) performance.
• Incorporating noble metals like ruthenium (Ru) into 3d transition metal phosphides presents challenges due to electronegativity differences.
• The electronic effects of noble metal alloying on HER remain incompletely understood.

Purpose of the Study:

• To investigate the effect of ruthenium (Ru) incorporation into iron phosphide (Fe₂P) single crystals on HER performance.
• To elucidate the electronic structure modifications induced by Ru doping and their impact on HER mechanisms.
• To establish a relationship between the electronic properties and catalytic activity of Ru-alloyed Fe₂P.

Main Methods:

• Synthesis of Ru-Fe₂P single crystals using the Bridgeman method.
• Electrochemical characterization of HER activity.
• Hall transport measurements and first-principles calculations to analyze electronic structure.

Main Results:

• Ru incorporation into Fe₂P effectively promoted HER.
• Ru acted as an electron dopant, increasing the Fermi level and lowering the water dissociation barrier.
• The (21̅1) facet of Ru-Fe₂P exhibited higher activity than the (001) facet due to a lower H desorption barrier.
• Synergistic effects between Ru and Fe sites facilitated H* and OH* desorption.

Conclusions:

• Ru-alloyed iron phosphides demonstrate enhanced HER performance.
• Electronic structure modulation by Ru doping is crucial for improving catalytic efficiency.
• This work provides insights into the structure-performance relationship for noble metal-alloyed phosphide catalysts.