title: Microwave-assisted synthesis of layered basic zinc acetate nanosheets and their thermal decomposition into nanocrystalline ZnO.
abstract: We have developed a low-cost technique using a conventional microwave oven to grow layered basic zinc acetate (LBZA) nanosheets (NSs) from a zinc acetate, zinc nitrate and HMTA solution in only 2 min. The as-grown crystals and their pyrolytic decomposition into ZnO nanocrystalline NSs are characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffraction (XRD) and photoluminescence (PL). SEM and AFM measurements show that the LBZA NSs have typical lateral dimensions of 1 to 5 μm and thickness of 20 to 100 nm. Annealing in air from 200°C to 1,000°C results in the formation of ZnO nanocrystalline NSs, with a nanocrystallite size ranging from 16 nm at 200°C to 104 nm at 1,000°C, as determined by SEM. SEM shows evidence of sintering at 600°C. PL shows that the shape of the visible band is greatly affected by the annealing temperature and that the exciton band to defect band intensity ratio is maximum at 400°C and decreases by a factor of 15 after annealing at 600°C. The shape and thickness of the ZnO nanocrystalline NSs are the same as LBZA NSs. This structure provides a high surface-to-volume ratio of interconnected nanoparticles that is favorable for applications requiring high specific area and low resistivity such as gas sensing and dye-sensitized solar cells (DSCs). We show that resistive gas sensors fabricated with the ZnO NSs showed a response of 1.12 and 1.65 to 12.5 ppm and 200 ppm of CO at 350°C in dry air, respectively, and that DSCs also fabricated from the material had an overall efficiency of 1.3%. PACS: 81.07.-b; 62.23.Kn; 61.82.Fk.
authors.forename: Afshin
authors.initials: A
authors.lastname: Tarat
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Nettle
authors.forename: Daniel T J
authors.initials: DT
authors.lastname: Bryant
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Jones
authors.forename: Mark W
authors.initials: MW
authors.lastname: Penny
authors.forename: Richard A
authors.initials: RA
authors.lastname: Brown
authors.forename: Ravish
authors.initials: R
authors.lastname: Majitha
authors.forename: Kenith E
authors.initials: KE
authors.lastname: Meissner
authors.affiliation: Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK. T.maffeis@Swansea.ac.uk.
authors.forename: Thierry G G
authors.initials: TG
authors.lastname: Maffeis