Oxygen defect engineering modifies NiFe₂O₄ for efficient detection of n-butanol gas

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Prussian blue analogs (PBA) are precursors for various functional materials.
• Oxygen vacancies play a crucial role in modulating the electronic properties of metal oxides.
• Developing highly sensitive and stable gas sensors for volatile organic compounds (VOCs) like n-butanol is essential.

Purpose of the Study:

• To develop a defect-rich spinel bimetallic oxide, NiFe2O4, for enhanced n-butanol gas sensing.
• To investigate the effect of weak base etching and sulfurization on PBA morphology and oxygen vacancy content.
• To demonstrate the superior gas sensing performance and stability of the modified NiFe2O4 material.

Main Methods:

• Synthesis of NiFe2O4 via weak base etching of PBA followed by sulfurization.
• Characterization of the material's morphology, structure, and defect content (oxygen vacancies).
• Fabrication and testing of a gas sensor using the modified NiFe2O4 for n-butanol detection.

Main Results:

• Weak base etching modified the morphology of PBA, and sulfur doping controlled oxygen vacancy content.
• The modified NiFe2O4-NCs@S exhibited a significantly enhanced response to n-butanol (59.29) compared to unmodified NiFe2O4-PBA (5.98) at 100 ppm and 275 °C.
• The sensor demonstrated excellent selectivity, long-term stability, and repeatability.
• Oxygen vacancies were confirmed to enhance gas-sensing properties by narrowing the band gap and modulating the electronic structure.

Conclusions:

• The proposed strategy of weak base etching and sulfurization effectively regulates oxygen vacancies in NiFe2O4, leading to superior n-butanol gas sensing.
• The defect-rich NiFe2O4-NCs@S material shows great potential for practical applications in high-performance gas sensing.
• Understanding the role of oxygen vacancies provides insights for designing next-generation gas sensors.