Sputtered Cu-doped NiO thin films as an efficient electrocatalyst for methanol oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Direct methanol oxidation is crucial for portable electrochemical energy systems.
• Efficient electrocatalysts are needed to improve performance and stability.
• Copper-doped Nickel Oxide (Cu-NiO) presents a promising material for electrocatalysis.

Purpose of the Study:

• To synthesize Cu-NiO thin films with varying thicknesses using co-sputtering.
• To investigate the structural, morphological, and surface properties of the films.
• To evaluate the electrocatalytic performance of Cu-NiO thin films for direct methanol oxidation.

Main Methods:

• Co-sputtering deposition of Cu-NiO thin films on fluorine-doped tin oxide (FTO) substrates.
• Characterization using X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Field emission scanning electron microscopy (FESEM), and Atomic force microscopy (AFM).
• Electrochemical evaluation of methanol oxidation using cyclic voltammetry and chronoamperometry.

Main Results:

• Successfully prepared Cu-NiO thin films with thicknesses ranging from 30 to 120 nm.
• XRD confirmed good crystallinity, while EDS verified film purity.
• FESEM and AFM characterized film thickness and surface roughness.
• Optimal electrocatalytic performance was observed in 1 M methanol, with a 60% increase in current density for the thickest film (1200s deposition).
• The thinnest film (30s deposition) exhibited an onset potential of 0.4 V vs. Ag/AgCl.
• Films demonstrated high stability and adhesion to the FTO substrate, eliminating the need for binders.

Conclusions:

• Film thickness significantly impacts the electrocatalytic activity for methanol oxidation.
• Co-sputtered Cu-NiO thin films are effective, binder-free electrocatalysts for direct methanol oxidation.
• Physical deposition techniques offer a viable route for optimizing electrocatalyst performance.