Spatially coupled Ni₂P/CoP-8 heterostructures with superwetting interfaces for high current density overall water...

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Water electrolysis is key for a sustainable hydrogen economy.
• Developing stable bifunctional catalysts for high current densities is a significant challenge.

Purpose of the Study:

• To develop a novel Ni2P/CoP-8 heterojunction catalyst with a unique architecture.
• To enhance bifunctional catalytic performance for hydrogen and oxygen evolution reactions at high current densities.

Main Methods:

• Fabrication of a Ni2P/CoP-8 heterojunction with a spatially coupled architecture (needle-like inner layer, sea-urchin-like outer layer).
• Electrochemical testing including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting.
• In situ Raman spectroscopy, Ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) calculations.

Main Results:

• The Ni2P/CoP-8 catalyst demonstrated prolonged durability (400 h) at 1000 mA cm-2.
• Achieved low overpotentials for HER (34 mV) and OER (196 mV).
• Enabled overall water splitting at 1.37 V to reach 10 mA cm-2, with electrochemically transformed surface layers (NiOOH/CoOOH) as active OER phases.

Conclusions:

• The heterointerface induces electron transfer, optimizing adsorption and enhancing intrinsic activity.
• The developed catalyst shows stable and highly active electrocatalysis for overall water splitting under high current density.
• This spatial coupling strategy contributes to practical applications in the hydrogen economy.