Few-Atomic-Layers Iron for Hydrogen Evolution from Water by Photoelectrocatalysis

Area of Science:

• Materials Science
• Catalysis
• Renewable Energy

Background:

• Water splitting for hydrogen production is crucial for energy and environmental solutions.
• Developing efficient and cost-effective catalysts is key to advancing this technology.

Purpose of the Study:

• To develop a highly active catalyst for the hydrogen evolution reaction (HER) using few-atomic-layer iron anchored on Gallium Nitride nanowire arrays.
• To investigate the catalytic properties and underlying mechanisms of this novel material system.

Main Methods:

• Fabrication of few-atomic-layer iron on Gallium Nitride nanowire arrays (Fe_FAL:GaN NWs).
• Electrochemical characterization including current density, overpotential, and Faradaic efficiency measurements.
• Density Functional Theory (DFT) calculations to understand hydrogen adsorption and electronic properties.

Main Results:

• Fe_FAL:GaN NWs demonstrated high activity for the hydrogen evolution reaction.
• DFT calculations revealed a low hydrogen free energy (-0.13 eV) on Fe_FAL:GaN NWs.
• The Fe_FAL:GaN NWs/n⁺-p Si heterostructure achieved a current density of ~ -30 mA cm^-2 at a low overpotential (~0.2 V) with 98% Faradaic efficiency under illumination.

Conclusions:

• Few-atomic-layer iron on Gallium Nitride nanowires is a highly active and efficient catalyst for the hydrogen evolution reaction.
• The catalyst's performance is attributed to spatial confinement, nitrogen-terminated surfaces, and strong electronic coupling.
• This material holds significant promise for scalable, carbon-free hydrogen production.