Fabrication of hierarchical flower-like porous ZnO nanostructures from layered ZnC2O4·3Zn(OH)2 and gas sensing properties

• Published in: Applied surface science Vol. 308; pp. 17 - 23
• Main Authors: Cui, Jiashan, Sun, Jianbo, Liu, Xin, Li, Jinwei, Ma, Xinzhi, Chen, Tingting
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 30-07-2014; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Gas sensing properties; Hierarchical and porous structures; Oxalic acid; Physics; ZnO; Hierarchical and porous structures; ZnO; Oxalic acid; Gas sensing properties; Inorganic compounds; Porous materials; Transition element compounds; Zinc oxide; Nanostructures
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.03.155

•Hierarchical flower-like porous ZnO nanostructures are synthesized.•Layered precursor of zinc oxalate hydroxide are first prepared with oxalic acid assistant facile hydrothermal method and according to the method, the material growth mechanism was discussed.•The sensor based on such flower-like porous ZnO nanostructures exhibits excellent gas sensitive properties for ethanol.
ZnO materials with porous and hierarchical flower-like structure were synthesized through mild hydrothermal and simple calcination approach, in which the flower-like layered zinc oxalate hydroxide (ZnC2O4·3Zn(OH)2) precursor was first synthesized and then calcined at 600°C. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopic (TEM), Brunauer–Emmett–Teller (BET) and thermogravimetric (TG) analysis. We proposed the possible growth mechanism of the material via studying the time evolution experiment results. In the process of reaction, oxalic acid as a structure-directing agent hydrolyzed and then formed primarily sheets-like intermediate ZnC2O4·2H2O. Hexamethylenetetramine (HMT) as surfactant, with directional adsorption, leads to the formation of layered zinc oxalate hydroxide precursor. Furthermore, the gas sensitivity also can be characterized, whose results indicated that the synthesized materials had a preferable selectivity to ethanol gas. The fast response rate and reversible performance can be attributed to the produced greater specific surface area produced, which was caused by the porous and hierarchical flower-like structure.