Useful High-Entropy Source on Spinel Oxides for Gas Detection.

Area of Science:

• Materials Science
• Chemistry
• Sensor Technology

Background:

• Spinel oxides are explored for gas detection applications.
• High-entropy materials offer unique properties due to multi-element composition.
• Previous studies focused on binary and ternary Ni-based ferrites.

Purpose of the Study:

• To identify a high-entropy spinel oxide for effective gas detection.
• To evaluate the sensor responses of various five-cation spinel oxides.
• To understand the semiconductor behavior and sulfurization effects.

Main Methods:

• Synthesis of six equimolar five-cation spinel oxides using the hydrothermal method.
• Evaluation of sensor responses to NO2, H2, NH3, and H2S.
• Analysis of semiconductor behavior (p-type vs. n-type) and sulfurization susceptibility.

Main Results:

• Five-element spinel oxides exhibited higher sensor responses than binary and ternary ferrites.
• Specific compositions showed distinct p-type or n-type semiconductor behavior towards NO2.
• A selective p-type response was observed for H2S, with enhanced sensitivity due to sulfurization.

Conclusions:

• High-entropy spinel oxides are effective for gas sensing, especially for H2S.
• The composition and cation distribution influence semiconductor properties.
• These findings provide a guideline for designing high-sensitivity spinel-type composite oxide gas sensors.