title: Hierarchical ZnO Nanosheet-Nanorod Architectures for Fabrication of Poly(3-hexylthiophene)/ZnO Hybrid NO2 Sensor.
abstract: A facile one-step solution method has been developed here to fabricate hierarchical ZnO nanosheet-nanorod architectures for compositing with poly(3-hexylthiophene) (P3HT) for fabricating a hybrid NO2 sensor. The hierarchical ZnO nanosheet-nanorod architectures were controllably synthesized by aging the solutions containing 0.05 mol·L(-1) Zn(2+) and 0.33 mol·L(-1) OH(-) at 60 °C through a metastable phase-directed mechanism. The concentration of OH(-) played a huge role on the morphology evolution. When the [OH(-)] concentration was decreased from 0.5 to 0.3 mol·L(-1), the morphology of the ZnO nanostructures changed gradually from monodispersed nanorods (NR) to nanorod assemblies (NRA), and then to nanosheet-nanorod architectures (NS-NR) and nanosheet assemblies (NSA), depending on the formation of various metastable, intermediate phases. The formation of NS-NR included the initial formation of ZnO nanosheets/γ-Zn(OH)2 mixed intermediates, followed by the dissolution of Zn(OH)2, which served as soluble zinc source. Soluble Zn(OH)2 facilitated the dislocation-driven secondary growth of ZnO nanorod arrays on the primary defect-rich nanosheet substrates. Hybrid sensors based on composite films composed of P3HT and the as-prepared ZnO nanostructures were fabricated for the detection of NO2 at room temperature. The P3HT/ZnO NS-NR bilayer film exhibited not only the highest sensitivity but also good reproducibility and selectivity to NO2 at room temperature. The enhanced sensing performance was attributed to the formation of the P3HT/ZnO heterojunction in addition to the enhanced adsorption of NO2 by NS-NR ZnO rich in oxygen-vacancy defects.
authors.affiliation: Department of Chemical Engineering, Tsinghua University , Beijing 100084, China.|Materials Research Institute, Materials Research Laboratory, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Microelectronics, Tsinghua University , Beijing 100084, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Materials Research Institute, Materials Research Laboratory, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Komarneni
authors.affiliation: Department of Chemical Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Haoyuan
authors.initials: H
authors.lastname: Chen
authors.affiliation: Institute of Microelectronics, Tsinghua University , Beijing 100084, China.
authors.forename: Jianlong
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Chemical Engineering, Tsinghua University , Beijing 100084, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Xiang
authors.affiliation: Institute of Microelectronics, Tsinghua University , Beijing 100084, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Xie
keywords: P3HT/ZnO heterojunction film; ZnO; metastable phase-directed synthesis; nanosheet−nanorod architectures; room-temperature NO2 sensor