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• 1. [Article] ZnO Nanosheet Arrays Constructed on Weaved Titanium Wire for CdS-Sensitized Solar Cells

  Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer ...

  Citation × Citation Citation Abstract Copy Title: ZnO Nanosheet Arrays Constructed on Weaved Titanium Wire for CdS-Sensitized Solar Cells Author: Wu, Cuncun, Wei, Lin, Li, Yitan, Liu, Chang, Jiao, Jun, Chen, Yanxue, Mei, Liangmo Year: 2014 Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer adsorption and reaction method to make a photoanode. Nanoparticle-sensitized solar cells were assembled using these CdS/ZnO nanostructured photoanodes, and their photovoltaic performance was studied systematically. The best light-to-electricity conversion efficiency was obtained to be 2.17% under 100 mW/cm/cm2 illumination, and a remarkable shortcircuit photocurrent density of approximately 20.1 mA/cm2 was recorded, which could attribute to the relatively direct pathways for transportation of electrons provided by ZnO nanosheet arrays as well as the direct contact between ZnO and weaved titanium wires. These results indicate that CdS/ZnO nanostructures on weaved titanium wires would open a novel possibility for applications of low-cost solar cells. Title: ZnO Nanosheet Arrays Constructed on Weaved Titanium Wire for CdS-Sensitized Solar Cells Author: Wu, Cuncun, Wei, Lin, Li, Yitan, Liu, Chang, Jiao, Jun, Chen, Yanxue, Mei, Liangmo Year: 2014 Ordered ZnO nanosheet arrays were grown on weaved titanium wires by a low-temperature hydrothermal method. CdS nanoparticles were deposited onto the ZnO nanosheet arrays using the successive ionic layer adsorption and reaction method to make a photoanode. Nanoparticle-sensitized solar cells were assembled using these CdS/ZnO nanostructured photoanodes, and their photovoltaic performance was studied systematically. The best light-to-electricity conversion efficiency was obtained to be 2.17% under 100 mW/cm/cm2 illumination, and a remarkable shortcircuit photocurrent density of approximately 20.1 mA/cm2 was recorded, which could attribute to the relatively direct pathways for transportation of electrons provided by ZnO nanosheet arrays as well as the direct contact between ZnO and weaved titanium wires. These results indicate that CdS/ZnO nanostructures on weaved titanium wires would open a novel possibility for applications of low-cost solar cells. Close

• 2. [Article] CdS Quantum Dot-Sensitized Solar Cells Based on Nano-Branched TiO2 Arrays

  Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored ...

  Citation × Citation Citation Abstract Copy Title: CdS Quantum Dot-Sensitized Solar Cells Based on Nano-Branched TiO2 Arrays Author: Liu, Chang, Li, Yitan, Wei, Lin, Wu, Cuncun, Chen, Yanxue, Mei, Liangmo, Jiao, Jun Year: 2014 Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks Title: CdS Quantum Dot-Sensitized Solar Cells Based on Nano-Branched TiO2 Arrays Author: Liu, Chang, Li, Yitan, Wei, Lin, Wu, Cuncun, Chen, Yanxue, Mei, Liangmo, Jiao, Jun Year: 2014 Nano-branched rutile TiO2 nanorod arrays were grown on F:SnO2 conductive glass (FTO) by a facile, two-step wet chemical synthesis process at low temperature. The length of the nanobranches was tailored by controlling the growth time, after which CdS quantum dots were deposited on the nano-branched TiO2 arrays using the successive ionic layer adsorption and reaction method to make a photoanode for quantum dot-sensitized solar cells (QDSCs). The photovoltaic properties of the CdS-sensitized nano-branched TiO2 solar cells were studied systematically. A short-circuit current intensity of approximately 7 mA/cm2 and a light-to-electricity conversion efficiency of 0.95% were recorded for cells based on optimized nano-branched TiO2 arrays, indicating an increase of 138% compared to those based on unbranched TiO2 nanorod arrays. The improved performance is attributed to a markedly enlarged surface area provided by the nanobranches and better electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunks Close

• 3. [Article] One-Dimensional Nanostructure and Sensing Applications: Tin Dioxide Nanowires and Carbon Nanotubes

  The key challenge for a nanomaterial based sensor is how to synthesize in bulk quantity and fabricate an actual device with insightful understanding of operational mechanisms during performance. I report ...

  Citation × Citation Citation Abstract Copy Title: One-Dimensional Nanostructure and Sensing Applications: Tin Dioxide Nanowires and Carbon Nanotubes Author: Tran, Hoang Anh Year: 2016 The key challenge for a nanomaterial based sensor is how to synthesize in bulk quantity and fabricate an actual device with insightful understanding of operational mechanisms during performance. I report here effective, controllable methods that exploit the concepts of the "green approach" to synthesize two different one-dimensional nanostructures, including tin oxide nanowires and carbon nanotubes. The syntheses are followed by product characterization and sensing device fabrications as well as sensor performance understanding at the molecular level. Sensor-analyte response and recovery kinetics are also presented. The first part of the thesis describes bulk-scale synthesis and characterization of tin oxide nanowires by the molten salt synthetic method and the nanowire doping with antimony (n-types) and lithium. The work builds on the success of using n-doped SnO2 nanoparticles to selectively detect chlorine gas at room temperature. Replacing n-doped nanoparticles with n-doped nanowires reduces the number of inter-particle electron hops between sensing electrodes. The nanowire based sensors show unprecedented 5 ppb detectability of corrosive Cl2 gas concentration in air. At the higher range, 10 ppm of Cl2 gas leads to a 250 fold increase in the device resistance. During sensor recovery, FT-IR studies show that dichlorine monoxide (Cl2O) and chlorine dioxide (ClO2) are the desorbing species. Long term stability of devices is affected by lattice oxygen vacancies replaced by chlorine atoms. Bulk-scale synthesis of multiwall carbon nanotube (MWCNTs) was achieved by a novel inexpensive synthetic method. The green chemistry method uses the non-toxic and easy to handle solid carbon source naphthalene. The synthesis is carried out by simply heating naphthalene and organometallic precursors as catalysts in a sealed glass tube. Synthesis at 610º C leads to MWCNTs of 50 nm diameter and lengths exceeding well over microns. MWCNT doping is attempted with nitrogen (n-type) and boron (p-type) precursors. Palladium nanoparticles decorated on as-synthesized MWCNTs are employed for specific detection of explosive hydrogen gas with concentrations far below the explosive concentration limits. During performance, the sensor exhibits abnormal response behaviors at hydrogen gas concentrations higher than 1%. A model of charge carrier inversion, brought about by reduction of MWCNT by hydrogen molecules dissociated by Pd nanoparticles is proposed. Title: One-Dimensional Nanostructure and Sensing Applications: Tin Dioxide Nanowires and Carbon Nanotubes Author: Tran, Hoang Anh Year: 2016 The key challenge for a nanomaterial based sensor is how to synthesize in bulk quantity and fabricate an actual device with insightful understanding of operational mechanisms during performance. I report here effective, controllable methods that exploit the concepts of the "green approach" to synthesize two different one-dimensional nanostructures, including tin oxide nanowires and carbon nanotubes. The syntheses are followed by product characterization and sensing device fabrications as well as sensor performance understanding at the molecular level. Sensor-analyte response and recovery kinetics are also presented. The first part of the thesis describes bulk-scale synthesis and characterization of tin oxide nanowires by the molten salt synthetic method and the nanowire doping with antimony (n-types) and lithium. The work builds on the success of using n-doped SnO2 nanoparticles to selectively detect chlorine gas at room temperature. Replacing n-doped nanoparticles with n-doped nanowires reduces the number of inter-particle electron hops between sensing electrodes. The nanowire based sensors show unprecedented 5 ppb detectability of corrosive Cl2 gas concentration in air. At the higher range, 10 ppm of Cl2 gas leads to a 250 fold increase in the device resistance. During sensor recovery, FT-IR studies show that dichlorine monoxide (Cl2O) and chlorine dioxide (ClO2) are the desorbing species. Long term stability of devices is affected by lattice oxygen vacancies replaced by chlorine atoms. Bulk-scale synthesis of multiwall carbon nanotube (MWCNTs) was achieved by a novel inexpensive synthetic method. The green chemistry method uses the non-toxic and easy to handle solid carbon source naphthalene. The synthesis is carried out by simply heating naphthalene and organometallic precursors as catalysts in a sealed glass tube. Synthesis at 610º C leads to MWCNTs of 50 nm diameter and lengths exceeding well over microns. MWCNT doping is attempted with nitrogen (n-type) and boron (p-type) precursors. Palladium nanoparticles decorated on as-synthesized MWCNTs are employed for specific detection of explosive hydrogen gas with concentrations far below the explosive concentration limits. During performance, the sensor exhibits abnormal response behaviors at hydrogen gas concentrations higher than 1%. A model of charge carrier inversion, brought about by reduction of MWCNT by hydrogen molecules dissociated by Pd nanoparticles is proposed. Close