Coprecipitation of nickel zinc malonate: A facile and reproducible synthesis route for Ni1−xZnxO nanoparticles and Ni1−xZnxO/ZnO nanocomposites via pyrolysis

Abstract

Nanoparticles of Ni1−xZnxO and Ni1−xZnxO/ZnO, which can be good candidates for selective gas sensors, were successfully obtained via a two-step synthetic route, in which the nickel zinc malonate precursor was first synthesized by co-precipitation from an aqueous solution, followed by pyrolysis in air at a relatively low temperature (~500°C). The precursor was characterized by ICP-AES, FTIR and TG and the results indicate the molecular structure of the precursor to be compatible with Ni1−xZnx(OOCCH2COO)·2H2O. The decomposition product, characterized using various techniques (FTIR, XRD, ToF-SIMS, SEM, TEM and XPS), was established to be a doped nickel oxide (Ni1−xZnxO for 0.01≤x≤0.1) and a composite material (Ni1−xZnxO/ZnO for 0.2≤x≤0.5). To elucidate the form in which the Zn is present in the NiO structure, three analytical techniques were employed: ToF-SIMS, XRD and XPS. While ToF SIMS provided a direct evidence of the presence of Zn in the NiO crystal structure, XRD showed that Zn actually substitutes Ni in the structure and XPS is a bit more specific by indicating that the Zn is present in the form of Zn2+ ions.