Robust Oxygen Evolution on Ni-Doped MoO₃: Overcoming Activity-Stability Trade-Off in Alkaline Water Splitting.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical water splitting is vital for green hydrogen production.
• Molybdenum trioxide (MoO3) is a potential catalyst for the oxygen evolution reaction (OER).
• MoO3 instability in alkaline media limits its application.

Purpose of the Study:

• To improve the activity and stability of MoO3 for alkaline electrochemical water splitting.
• To investigate nickel (Ni) doping as a strategy to overcome the activity-stability trade-off in OER catalysts.
• To understand the mechanism and stability of Ni-doped MoO3.

Main Methods:

• Density functional theory (DFT) calculations with Hubbard corrections.
• Experimental electrochemical water splitting measurements.
• X-ray photoelectron spectroscopy (XPS) for stability analysis.

Main Results:

• Ni doping reduced the thermodynamic OER overpotential to 0.64 V (DFT).
• Experimental overpotentials for Ni-doped MoO3 were 0.34 V at 10 mA/cm2 and 0.56 V at 100 mA/cm2.
• Ni-doped MoO3 showed enhanced stability and a lower Tafel slope (74.8 mV/dec) compared to pristine MoO3 (98.3 mV/dec).

Conclusions:

• Ni-doped MoO3 is a promising electrocatalyst for alkaline water splitting.
• Ni doping effectively mitigates MoO3 instability and enhances OER performance.
• The findings offer insights into dopant selection for improving catalyst activity and stability.