Porous CoFe2O4 nanorods: VOC gas-sensing characteristics and DFT calculation

Gas-sensing properties of metal oxide are strongly dependent on the morphology, porosity, and crystal size; thus, researchers are trying to improve the sensitivity by using nanomaterials. This study synthesized porous CoFe2O4 (CFO) nanorods with large specific surface area and fine crystal size for volatile organic compounds (VOCs) gas sensor application. The porous CFO nanorods were synthesized by a simple hydrothermal method and subsequent calcination at high temperatures. Results pointed out that the single-phase porous CFO nanorods with diameter and length of ∼500 and ∼4 µm, respectively, were obtained. The nanorod has a porous structure, with a pore size of ∼100 nm, formed from interconnected nanocrystals of an average crystal size of ∼18 nm. The porous CFO nanorods showed the best response to acetone at 350 °C and were suitable for practical application. The adsorption trend (adsorption energy and charge transfer between adsorbent and molecules) is also clarified by the nonempirical van der Waals density functional theory calculation.