Interface Charge Transfer Engineering in NiFe Layered Double Hydroxide-Cs_0.32WO₃ Heterostructures for Enhanced Oxygen...

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Electrochemical water splitting is crucial for sustainable hydrogen production.
• The oxygen evolution reaction (OER) is kinetically limited by high overpotentials, hindering water electrolysis efficiency.
• Nickel-iron layered double hydroxide (NiFe-LDH) shows promise as an OER catalyst but suffers from low conductivity.

Purpose of the Study:

• To synthesize a NiFe-LDH/Cs$_{0.32}$WO$_{3}$ heterojunction composite catalyst.
• To enhance the charge transfer efficiency and catalytic performance of NiFe-LDH for OER.
• To investigate the mechanism of performance improvement in the heterojunction catalyst.

Main Methods:

• Hydrothermal synthesis of NiFe-LDH/Cs$_{0.32}$WO$_{3}$ composite.
• Electrochemical testing (overpotential, Tafel slope, charge transfer resistance).
• X-ray photoelectron spectroscopy (XPS) for interfacial charge transfer analysis.

Main Results:

• The NiFe-LDH/Cs$_{0.32}$WO$_{3}$-20 mg catalyst achieved a low overpotential (349 mV at 10 mA cm$^{-2}$), reduced Tafel slope (67.0 mV dec$^{-1}$), and lower charge transfer resistance (65.1 Ω).
• Performance improvements represent significant decreases compared to pure NiFe-LDH.
• XPS confirmed interfacial charge transfer from Cs$_{0.32}$WO$_{3}$ to NiFe-LDH, evidenced by a negative shift in W4f peaks.

Conclusions:

• The NiFe-LDH/Cs$_{0.32}$WO$_{3}$ heterojunction effectively enhances OER kinetics by improving charge transfer and electronic structure.
• The synergistic effect at the heterojunction interface is key to the improved catalytic performance.
• This work offers insights into designing efficient heterojunction electrocatalysts for water splitting.