Oxygen Vacancy and Heterostructure Modulation of Co₂P/Fe₂P Electrocatalysts for Improving Total Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Developing efficient catalysts for hydrogen evolution (HER) and oxygen evolution (OER) is critical for industrial hydrogen energy.
• Current challenges include achieving high activity, stability, and cost-effectiveness in nonprecious metal catalysts.

Purpose of the Study:

• To fabricate a coupled cobalt and iron phosphide (Co2P/Fe2P) nanorod array catalyst.
• To investigate its performance for overall water splitting.
• To elucidate the mechanisms behind its enhanced catalytic activity.

Main Methods:

• Synthesis of Co2P/Fe2P nanorod arrays via a simple fabrication approach.
• Electrochemical characterization of the catalyst for HER and OER in alkaline media.
• Analysis of interfacial properties, including oxygen vacancies and electronic interactions.

Main Results:

• The Co2P/Fe2P heterostructure catalyst achieved low overpotentials of 96 mV for HER and 220 mV for OER at 10 mA cm-2.
• Achieved a low voltage of 1.56 V for overall water splitting at 10 mA cm-2.
• Demonstrated excellent long-term durability for 30 hours at a high current density of 250 mA cm-2.

Conclusions:

• The catalyst's superior performance is attributed to interfacial oxygen vacancies and strong Co2P/Fe2P interactions, enhancing active sites and charge transfer.
• The formation of active metal (oxy)hydroxide phases contributes to OER stability.
• This work presents a viable strategy for designing advanced nonprecious metal phosphide electrocatalysts for industrial electrolysis.