Formation of ZnFe2O4/ZnO:Al thin film heterostructure with the peroxidase mimetic properties by RF-magnetron sputtering method

Abstract

In recent years analytical methods based on the catalytic activity of nanoparticles with the

properties of the peroxidase mimetic, such as palladium nanoparticles, porous cobalt oxide nanostructures and others, have been successfully used to detect pollutants in the environment [1].

In our work we propose ZnFe2O4/ZnO:Al film heterostructures that were obtained by magnetron sputtering in an argon atmosphere as a mimetic of the peroxidase enzyme for the detection of

hydrogen peroxide in model experiments. The morphology and chemical composition of

ZnFe2O4/ZnO:Al thin films were studied using a Zeiss Sigma scanning electron microscope and Tescan

Vega TS 5130MM equipped with an Oxford Instruments INCA energy dispersive X-ray system operating at a voltage of 20 kV. The study of the chemical composition obtained using X-ray spectroscopy (EDX) shows in the case of thin layer of ZnO:Al, along with the main elements Zn, O, Al, elements similar to glass (Ca, Si, Mg, O) as well as Zn, Fe, O, for ZnFe2O4/ZnO:Al film nanostructures. In Fig.1 (a) and (b) are presented SEM EDX of ZnO:Al thin film and ZnFe2O4/ZnO:Al heterostructure respectively. The comparison of the X-ray diffraction (Desktop X-ray diffractometer Miniflex 600 Rigaku) of the obtained thin films in Fig.2 (2) with a diffraction pattern from the JCPDS database No. 22-1012 presented in Fig.2 (3) shows the presence of peaks corresponding to (111), (220), (311), (222), (400), (422), (511), (440) phases of cubic spinel (Franklinite). In Fig.2 (1) specific peaks related to ZnO in the

ZnFe2O4/ZnO:Al/glass heterostructure are presented. The ZnO sample shows the specific peaks at 2θ = 31.7° (100), 34.4° (002) and 56.5° (110) corresponding to the hexagonal structure of wurtzite type

(ICDD No.01-078-2585). The peroxidase activity of the ZnFe2O4/ZnO:Al/glass films structure was studied using 3,3', 5,5'-tetramethylbenzidine (TMB) as a peroxidase substrate in the presence of H2O2 according to the procedure described in [2].