Constructing a Built-In Electric Field To Accelerate Water Dissociation for Efficient Alkaline Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The alkaline hydrogen evolution reaction (HER) is crucial for sustainable hydrogen production.
• Water dissociation kinetics significantly impact HER efficiency.
• Developing advanced electrocatalysts is key to overcoming HER limitations.

Purpose of the Study:

• To design and synthesize a novel heterogeneous electrocatalyst for enhanced alkaline HER.
• To investigate the role of p-n junctions in improving water dissociation and HER performance.
• To understand the mechanism by which the built-in electric field influences catalytic activity.

Main Methods:

• Synthesis of a nickel phosphide/cobalt phosphide nanowire array on nickel foam (Ni2P/CoP/NF).
• Fabrication of a p-n junction structure within the catalyst.
• Electrochemical characterization of the catalyst for alkaline HER in 1 M KOH.
• Computational calculations to elucidate the mechanism of action.

Main Results:

• The Ni2P/CoP/NF catalyst exhibited a p-n junction structure with a built-in electric field (BEF).
• Achieved low overpotentials of 58 mV at 30 mA cm-2 and 118 mV at 100 mA cm-2.
• Demonstrated excellent stability over 40 hours at 300 mA cm-2.
• Computational and experimental results confirmed the BEF promotes water dissociation and optimizes intermediate binding.

Conclusions:

• The p-n junction in Ni2P/CoP/NF effectively enhances alkaline HER by promoting water dissociation.
• The BEF plays a critical role in regulating intermediate adsorption/desorption and electron transport.
• This study offers a rational design strategy for high-performance heterogeneous electrocatalysts for HER.