Reversible Room Temperature H₂ Gas Sensing Based on Self-Assembled Cobalt Oxysulfide

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Room-temperature hydrogen gas sensing is crucial for IoT, zero-emission vehicles, and fuel cells.
• Conventional metal oxide sensors require high temperatures, leading to high power consumption and poor selectivity.
• Developing efficient, low-power, and selective gas sensors remains a significant challenge.

Purpose of the Study:

• To investigate cobalt oxysulfide as a novel material for room-temperature hydrogen gas sensing.
• To explore the gas sensing mechanism and performance of cobalt oxysulfide.
• To demonstrate the potential of transition metal oxysulfides for advanced gas sensing applications.

Main Methods:

• Synthesis of cobalt oxysulfide via calcination of self-assembled cobalt sulfide micro-cages.
• Characterization of the material's crystal structure and optical bandgap.
• Evaluation of hydrogen gas sensing performance, including reversibility, response magnitude, and selectivity at room temperature.

Main Results:

• Cobalt oxysulfide exhibits a transformed crystal structure with oxygen replacing sulfur, and a slightly expanded optical bandgap.
• The material demonstrates fully reversible hydrogen gas sensing at room temperature.
• A p-type gas response of 15% for 1% H2 was observed, with high selectivity over methane, nitrogen dioxide, and carbon dioxide.

Conclusions:

• Cobalt oxysulfide is a promising material for highly selective, room-temperature, and reversible hydrogen gas sensing.
• The sensing mechanism is likely dominated by physisorption, enabling low-power operation.
• Transition metal oxysulfides offer significant potential for next-generation gas sensing technologies.