Steps towards highly-efficient water splitting and oxygen reduction using nanostructured β-Ni(OH)₂.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing efficient electrocatalysts is crucial for renewable energy technologies.
• Nickel hydroxide (Ni(OH)₂) is explored for its potential in electrochemical applications.
• Nanostructured materials offer enhanced catalytic properties due to increased surface area.

Purpose of the Study:

• To synthesize and characterize β-Ni(OH)₂ nanoplatelets.
• To evaluate the electrocatalytic activity of β-Ni(OH)₂ for oxygen reduction, oxygen evolution, and hydrogen evolution reactions.
• To assess the stability and performance metrics of the synthesized material.

Main Methods:

• Hydrothermal synthesis of β-Ni(OH)₂ nanoplatelets.
• Characterization using scanning and transmission electron microscopy (SEM/TEM).
• Analysis via X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS).
• Electrochemical testing in alkaline media.

Main Results:

• β-Ni(OH)₂ nanoplatelets exhibit efficient electrocatalysis for OER, HER, and ORR.
• Oxygen evolution reaction (OER) shows an overpotential of 498 mV with a Tafel slope of 149 mV dec⁻¹ (improving to 99 mV dec⁻¹ at 75 °C).
• Hydrogen evolution reaction (HER) demonstrates a low overpotential of -333 mV with a Tafel slope of -230 mV dec⁻¹ (improving to -65 mV at 75 °C).
• Oxygen reduction reaction (ORR) displays a Tafel slope of -78 mV dec⁻¹ and 4.01 exchanged electrons, indicating a direct 4e⁻ pathway.

Conclusions:

• β-Ni(OH)₂ nanoplatelets are effective electrocatalysts for key reactions in alkaline media.
• The material exhibits superior catalytic activity and stability compared to previous reports.
• This work highlights the potential of nanostructured nickel hydroxide for energy applications.