Transient mixed-valent Ni active sites boost urea electrooxidation

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Electrocatalytic reactions often suffer from slow kinetics.
• Synergistic multivalent active sites offer a promising strategy to overcome these limitations.

Purpose of the Study:

• To develop a novel catalyst for enhanced urea oxidation reaction (UOR).
• To leverage the localized surface plasmon resonance (LSPR) effect for improved electrocatalysis.

Main Methods:

• Preparation of Au ultrafine nanoparticles/Ni-1,4-naphthalenedicarboxylic acid (Au uNPs/Ni-NDC) composite.
• Utilizing light excitation to induce hot electron transfer and generate multivalent active sites.
• Employing operando X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and ultrafast transient absorption (TA) spectroscopy.
• Performing density functional theory (DFT) calculations.

Main Results:

• Au uNPs/Ni-NDC demonstrated a twofold increase in UOR current under light.
• A significant negative shift in the UOR onset potential was observed.
• Formation of Ni^(3-σ)+-Ni³⁺ mixed-valent active sites was confirmed via spectroscopy.
• DFT calculations revealed the Ni^(3-σ)+-Ni³⁺ mechanism promotes UOR kinetics.

Conclusions:

• The developed Au uNPs/Ni-NDC catalyst effectively enhances UOR through light-driven multivalent active sites.
• The synergistic effect between Au nanoparticles and Ni-NDC creates efficient pathways for urea oxidation.
• This approach provides a new avenue for designing advanced electrocatalysts.