Lattice Strain-Modulated Trifunctional CoMoO₄ Polymorph-Based Electrodes for Asymmetric Supercapacitors and...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage and Conversion

Background:

• Developing efficient electrodes is critical for energy storage and conversion devices.
• Multifunctional electrodes are needed for applications like supercapacitors and water splitting.
• Cobalt molybdate (CoMoO4) and cobalt oxide (Co3O4) heterostructures are promising electrode materials.

Purpose of the Study:

• To engineer lattice strain in CoMoO4 within a CoMoO4@Co3O4 heterostructure using phosphorus doping.
• To investigate the performance of the phosphorus-doped heterostructure (P-CoMoO4@Co3O4) as a trifunctional electrode.
• To evaluate its capabilities for supercapacitors (SCs), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER).

Main Methods:

• Synthesis of P-CoMoO4@Co3O4 heterostructures with controlled phosphorus doping.
• Characterization of lattice strain, specifically a +2.42% tensile strain in the β-phase CoMoO4.
• Electrochemical testing for supercapacitor performance, HER, and OER in alkaline electrolytes.

Main Results:

• The P-CoMoO4@Co3O4 electrode exhibited superior electrochemical performance compared to undoped counterparts.
• Achieved high energy density (118 Wh kg-1) in an asymmetric supercapacitor.
• Demonstrated low overpotentials for HER (189 mV) and OER (365 mV) at 500 mA cm-2, enabling low overall water splitting voltage (1.71 V).

Conclusions:

• Phosphorus doping induces beneficial lattice strain in β-phase CoMoO4, significantly boosting trifunctional electrode performance.
• The P-CoMoO4@Co3O4 heterostructure shows excellent potential for integrated energy storage and hydrogen production.
• Practical demonstration in an alkaline seawater electrolyzer highlights its viability for future sustainable energy technologies.