P-type cobaltite oxide spinels enable efficient electrocatalytic oxygen evolution reaction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Energy-efficient electrocatalytic oxygen evolution typically relies on expensive noble metal oxides.
• Developing cost-effective and highly active electrocatalysts is crucial for sustainable energy technologies.

Purpose of the Study:

• To investigate the electrocatalytic activity and stability of a highly p-conducting zinc cobaltite spinel (Zn_1.2Co_1.8O_3.5) for oxygen evolution.
• To explore the potential of this material as an alternative to noble metal oxides in water electrolysis.

Main Methods:

• Manufacturing off-stoichiometric conducting p-spinel catalytic anodes on various carriers (tetragonal Ti, Au-Ti, hexagonal Al-doped ZnO).
• Electrochemical characterization including Tafel slope analysis and overpotential measurements at a current density of 10 mA cm^-2.
• Assessing anodic stability through 50 hours of continuous oxygen evolution in 1 M KOH.

Main Results:

• The synthesized Zn_1.2Co_1.8O_3.5 spinel exhibited enhanced electrocatalytic activity for oxygen evolution.
• Tafel slopes ranged from 40.5 to 48 mV dec^-1, with overpotentials between 0.35 and 0.43 V.
• The anodes demonstrated excellent anodic stability, operating continuously for 50 hours in 1 M KOH.

Conclusions:

• Increasing the electrical conductivity of p-type Zn-Co spinels is advantageous for oxygen evolution electrolysis, reducing ohmic losses.
• Optimized growth on tetragonal Ti carriers enhances p-doping and results in dimension-stable 3d-metal anodes.
• Zinc cobaltite spinel presents a promising, cost-effective alternative to noble metal oxides for electrocatalytic oxygen evolution.