The alarming rise of indoor pollution and the need to combat the associated negative effects have promoted increasing attention in modernizing the chemical sensing technologies by newly designed materials with rich and tunable functionalities at atomic or molecular levels. With the appealing physical, chemical, optical, and electronic properties for various potential applications, the state-of-art gas-sensing nanomaterials and their future perspectives are well-documented and summarized in this paper. Specifically, the key performance attributes are addressed in detail such as the sensitivity, selectivity, reversibility, operating temperature, response time, and detection limit. As such, this review provides both critical insights in exploring and understanding various gas sensing nanomaterials and points out limitations and opportunities for further developments, such as morphology control, doping and surface alteration, atomic-scale characterization, and applications in different fields. Finally, the challenges and outlooks are discussed on the basis of the current developments.

Functional gas sensing nanomaterials: A panoramic view

Photocatalytic activity evaluation of tetragonal CuFe2O4 nanoparticles for the H2 evolution under visible light irradiation

Magnetic and catalytic properties of cubic copper ferrite nanopowders synthesized from secondary resources

Soft ferrites are very important electronic materials because of their electrical and magnetic behavior. In last decade, remarkable efforts have been taken for the development of ferrite gas sensors in detection of toxic gas pollutants from vehicle exhaust, biological hazards, environment, and pollution monitoring. The parameters such as phase formation, crystallite size, particle size, grain size, dopants, surface area, sensitivity, selectivity, operating temperature, gas concentration, response time, and recovery time play an important role in development of ferrite gas sensors. These material for gas sensing covers number of gases such as carbon monoxide (CO), carbon dioxide (CO2 ), methane (CH4), ethyl alcohol (C2H5OH), hydrogen sulphide (H2S), C2H5COOH, oxygen (O2), hydrogen (H2), chlorine (Cl2), NH3, C4H10, CH3COOH , gasoline, acetylene, petrol, and liquefied petroleum gas (LPG). Different methods are used to prepare ferrite gas sensors. The prime requisite for developing a good quality ferrite gas sensor is optimization of preparation conditions, sintering temperature, operating temperatures, concentration of dopants, etc. It is observed that the gas sensitivity depends on kinds of semiconducting material, temperature, and test gases to be detected. This paper provides comprehensive survey of ferrites as gas sensors, such as nickel, copper, zinc, cadmium, cobalt, magnesium, manganese, and multi-component ferrites, prepared by various methods. The performance of these sensors including sensitivity, selectivity, stability, as well as response and recovery time, etc., are summarized in the table along with relevant references.

Ferrite Gas Sensors

Preparation of nanometer CuFe2O4 by auto-combustion and its catalytic activity on the thermal decomposition of ammonium perchlorate

Semiconductive nanometer-size material CuFe2O4 was synthesized by a low-heating solid-state reaction of inorganic reagents of Cu(CH3COO)2·H2O, Fe(NO3)3·9H2O and NaOH. The process was a convenient, environment friendly, inexpensive and efficient preparation method for the CuFe2O4 nanomaterial. X-ray diffraction (XRD) was used to confirm the material structure and scanning electron microscopy (SEM) to depict the crystallite microstructure. Conductance responses of the nanocrystalline CuFe2O4 thick film were measured by exposing the film to reducing gases of ammonia (NH3), acetone (CH3COCH3), hydrogen (H2) and ethanol gas (C2H5OH). It was found that the sensor exhibited various sensing responses to these gases at different operating temperatures. Furthermore, the sensor exhibited a fast response and a good recovery.

Dian zeng Jia

Papers

Simple synthesis of CuFe2O4 nanoparticles as gas-sensing materials