The Experts below are selected from a list of 1626 Experts worldwide ranked by ideXlab platform

Sheryl H Ehrma - One of the best experts on this subject based on the ideXlab platform.

  • Copper Oxide Nanoparticle made by flame spray pyrolysis for photoelectrochemical water splitting part i cuo Nanoparticle preparation
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Chiaying Chiang, Kosi C Aroh, Sheryl H Ehrma
    Abstract:

    Abstract Copper Oxide (CuO) semiconductor Nanoparticles are of interest because of their promising use for electronic and optoelectronic devices, and the size of the CuO particles for these applications is important. In this work, near spherical CuO Nanoparticles with aspect ratio of 1.2–1.3 were made by a flame spray pyrolysis (FSP) method. In FPS, flame temperature, residence time, precursor concentration can be used to control particle size. As the precursor concentration increased from 0.5% to 35% w/w, primary particle diameter increased from 7 ± 2 to 20 ± 11 nm. Larger primary particle diameters were observed in the low gas flow system (set B) due to the long residence time in the high temperature zone. For the dependence of temperature on particle diameter, particles grew to similar diameter, i.e. ∼11 nm, in both flame conditions within the hot temperature zone (80% of melting point of CuO) but for particles having longer residence time, i.e. 550 ms in set B, the standard deviation of particle diameter is 45% larger than for particles with 66 ms as residence time in set A. Modeling gave a result for CuO final particle diameter, based on collision/sintering theory with sintering by solid state diffusion, of 6.7 and 9.0 nm for set A and set B, respectively, with surface tension assumed to be 0.5 J/m 2 .Comparison with the experiment results, 11 ± 4 nm diameter for both flame conditions, indicates the simulations were reasonable.

  • Copper Oxide Nanoparticle made by flame spray pyrolysis for photoelectrochemical water splitting part ii photoelectrochemical study
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Chiaying Chiang, Kosi C Aroh, Nicholas Franso, Vibha R Satsangi, Sahab Dass, Sheryl H Ehrma
    Abstract:

    Abstract A scalable method for hydrogen generation by splitting water via a photoelectrochemical cell was studied. Flame spray pyrolysis and spin coating processing methods were used for preparing Copper Oxide Nanoparticles and Copper Oxide photocathodes. Copper Oxide p-type semiconductor Nanoparticles made by flame spray pyrolysis were spin coated on conducting ITO substrates and served as photocathodes for photoelectrochemical splitting of water. The film thickness was controlled by the concentration of the CuO suspension solution and numbers of layer deposited on the substrate. As sintering temperature increased to 600 °C, crystalline diameter increased from 28 nm (before sintering) to 110 nm and the bandgaps decreased from 1.68 eV to 1.44 eV. A 387 nm thickness CuO film with bandgap 1.44 eV was demonstrated to have 1.48% total conversion efficiency and 0.91% photon-to-hydrogen generation efficiency. The net photocurrent density (photocurrent – dark current) was measured to be 1.20 mA/cm 2 at applied voltage of −0.55 V vs. Ag/AgCl in 1 M KOH electrolyte with 1 sun (AM1.5G) illumination. Based on the Mott–Schottky plot, the carrier density was estimated to be 1.5 × 10 21  cm −3 and the flatband potential to be 0.23 V vs. Ag/AgCl. Furthermore, the valence band edge and conduction band levels were found to lie at −5.00 eV and −3.56 eV respect to the vacuum respectively.

Esko I Kauppinen - One of the best experts on this subject based on the ideXlab platform.

  • Copper and Copper Oxide Nanoparticle formation by chemical vapor nucleation from Copper ii acetylacetonate
    Journal of Nanoparticle Research, 2001
    Co-Authors: Albert G. Nasibulin, Olivier Richard, Esko I Kauppinen, Petri Ahonen, Igor S. Altman
    Abstract:

    Crystalline nanometer-size Copper and Copper (I) Oxide particle formation was studied by thermal decomposition of Copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of P prec = 0.06 to 44 Pa at furnace temperatures of 431.5°C, 596.0°C, and 705.0°C. Agglomerates of primary particles were formed at P prec0.1 Pa at all temperatures. At 431.5°C the number mean size of the primary particles increased from D p = 3.7 nm (with geometric standard deviation σg = 1.42) to D p = 7.2 nm (σg = 1.33) with the increasing precursor vapor particle pressure from 1.8 to 16 Pa. At 705.0°C the primary particle size decreased from D p = 24.0 nm (σg=1.57) to D p = 7.6 nm (σg = 1.54), respectively. At furnace temperatures of 431.5°C and 596.0°C only crystalline Copper particles were produced. At 705.0°C the crystalline product of the decomposition depended on the precursor vapor pressure: Copper particles were formed at P prec>10 Pa, Copper (I) Oxide at P precleq 1 Pa, and a mixture of the metal and its Oxide at intermediate vapor pressures. A kinetic restriction on Copper particle growth was shown, which leads to the main role of Cu2 molecule participation in the particle formation. The formation of Copper (I) Oxide particles occurs due to the surface reaction of the decomposition products (mainly carbon diOxide). For the explanation of the experimental results, a model is proposed to build a semiempirical phase diagram of the precursor decomposition products.

  • Copper and Copper Oxide Nanoparticle Formation by Chemical Vapor Nucleation From Copper (II) Acetylacetonate
    Journal of Nanoparticle Research, 2001
    Co-Authors: Albert G. Nasibulin, P. Petri Ahonen, Olivier Richard, Esko I Kauppinen, Igor S. Altman
    Abstract:

    Crystalline nanometer-size Copper and Copper (I) Oxide particle formationwas studied by thermal decomposition of Copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of Pprec = 0.06 to 44Pa at furnace temperatures of 431.5◦ C, 596.0◦C, and 705.0◦ C. Agglomerates of primary particles were formed at Pprec > 0.1Pa at all temperatures. At 431.5◦ C the number mean size of the primary particles increased from Dp = 3.7 nm (with geometric standard deviation σg = 1.42) to Dp = 7.2nm (σg = 1.33) with the increasing precursor vapor particle pressure from 1.8 to 16Pa. At 705.0◦C the primary particle size decreased fromDp = 24.0nm(σg = 1.57) toDp = 7.6nm(σg = 1.54), respectively. At furnace temperatures of 431.5◦ C and 596.0◦ C only crystalline Copper particles were produced. At 705.0◦ C the crystalline product of the decomposition depended on the precursor vapor pressure: Copper particles were formed at Pprec > 10 Pa, Copper (I) Oxide at Pprec ≤ 1Pa, and a mixture of the metal and its Oxide at intermediate vapor pressures. A kinetic restriction on Copper particle growth was shown, which leads to the main role of Cu2 molecule participation in the particle formation. The formation of Copper (I) Oxide particles occurs due to the surface reaction of the decomposition products (mainly carbon diOxide). For the explanation of the experimental results, a model is proposed to build a semiempirical phase diagram of the precursor decomposition products.

  • Copper and Copper Oxide Nanoparticle formation by chemical vapor nucleation from Copper ii acetylacetonate
    Journal of Aerosol Science, 2000
    Co-Authors: Albert G. Nasibulin, Olivier Richard, Petri Ahonen, Esko I Kauppinen
    Abstract:

    This work is devoted to the investigation of Copper and Copper Oxide particle formation from metal-organic compound, Copper(II) acetylacetonate. The goals of the investigation are to produce Copper and/or Copper Oxide Nanoparticles at ambient pressure and at temperature as low as possible, to characterize the obtained Nanoparticles synthesized with various reactor conditions, and to discuss the mechanisms of the Nanoparticle formation based on the experimental results.

Albert G. Nasibulin - One of the best experts on this subject based on the ideXlab platform.

  • Copper and Copper Oxide Nanoparticle formation by chemical vapor nucleation from Copper ii acetylacetonate
    Journal of Nanoparticle Research, 2001
    Co-Authors: Albert G. Nasibulin, Olivier Richard, Esko I Kauppinen, Petri Ahonen, Igor S. Altman
    Abstract:

    Crystalline nanometer-size Copper and Copper (I) Oxide particle formation was studied by thermal decomposition of Copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of P prec = 0.06 to 44 Pa at furnace temperatures of 431.5°C, 596.0°C, and 705.0°C. Agglomerates of primary particles were formed at P prec0.1 Pa at all temperatures. At 431.5°C the number mean size of the primary particles increased from D p = 3.7 nm (with geometric standard deviation σg = 1.42) to D p = 7.2 nm (σg = 1.33) with the increasing precursor vapor particle pressure from 1.8 to 16 Pa. At 705.0°C the primary particle size decreased from D p = 24.0 nm (σg=1.57) to D p = 7.6 nm (σg = 1.54), respectively. At furnace temperatures of 431.5°C and 596.0°C only crystalline Copper particles were produced. At 705.0°C the crystalline product of the decomposition depended on the precursor vapor pressure: Copper particles were formed at P prec>10 Pa, Copper (I) Oxide at P precleq 1 Pa, and a mixture of the metal and its Oxide at intermediate vapor pressures. A kinetic restriction on Copper particle growth was shown, which leads to the main role of Cu2 molecule participation in the particle formation. The formation of Copper (I) Oxide particles occurs due to the surface reaction of the decomposition products (mainly carbon diOxide). For the explanation of the experimental results, a model is proposed to build a semiempirical phase diagram of the precursor decomposition products.

  • Copper and Copper Oxide Nanoparticle Formation by Chemical Vapor Nucleation From Copper (II) Acetylacetonate
    Journal of Nanoparticle Research, 2001
    Co-Authors: Albert G. Nasibulin, P. Petri Ahonen, Olivier Richard, Esko I Kauppinen, Igor S. Altman
    Abstract:

    Crystalline nanometer-size Copper and Copper (I) Oxide particle formationwas studied by thermal decomposition of Copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of Pprec = 0.06 to 44Pa at furnace temperatures of 431.5◦ C, 596.0◦C, and 705.0◦ C. Agglomerates of primary particles were formed at Pprec > 0.1Pa at all temperatures. At 431.5◦ C the number mean size of the primary particles increased from Dp = 3.7 nm (with geometric standard deviation σg = 1.42) to Dp = 7.2nm (σg = 1.33) with the increasing precursor vapor particle pressure from 1.8 to 16Pa. At 705.0◦C the primary particle size decreased fromDp = 24.0nm(σg = 1.57) toDp = 7.6nm(σg = 1.54), respectively. At furnace temperatures of 431.5◦ C and 596.0◦ C only crystalline Copper particles were produced. At 705.0◦ C the crystalline product of the decomposition depended on the precursor vapor pressure: Copper particles were formed at Pprec > 10 Pa, Copper (I) Oxide at Pprec ≤ 1Pa, and a mixture of the metal and its Oxide at intermediate vapor pressures. A kinetic restriction on Copper particle growth was shown, which leads to the main role of Cu2 molecule participation in the particle formation. The formation of Copper (I) Oxide particles occurs due to the surface reaction of the decomposition products (mainly carbon diOxide). For the explanation of the experimental results, a model is proposed to build a semiempirical phase diagram of the precursor decomposition products.

  • Copper and Copper Oxide Nanoparticle formation by chemical vapor nucleation from Copper ii acetylacetonate
    Journal of Aerosol Science, 2000
    Co-Authors: Albert G. Nasibulin, Olivier Richard, Petri Ahonen, Esko I Kauppinen
    Abstract:

    This work is devoted to the investigation of Copper and Copper Oxide particle formation from metal-organic compound, Copper(II) acetylacetonate. The goals of the investigation are to produce Copper and/or Copper Oxide Nanoparticles at ambient pressure and at temperature as low as possible, to characterize the obtained Nanoparticles synthesized with various reactor conditions, and to discuss the mechanisms of the Nanoparticle formation based on the experimental results.

Chiaying Chiang - One of the best experts on this subject based on the ideXlab platform.

  • Copper Oxide Nanoparticle made by flame spray pyrolysis for photoelectrochemical water splitting part i cuo Nanoparticle preparation
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Chiaying Chiang, Kosi C Aroh, Sheryl H Ehrma
    Abstract:

    Abstract Copper Oxide (CuO) semiconductor Nanoparticles are of interest because of their promising use for electronic and optoelectronic devices, and the size of the CuO particles for these applications is important. In this work, near spherical CuO Nanoparticles with aspect ratio of 1.2–1.3 were made by a flame spray pyrolysis (FSP) method. In FPS, flame temperature, residence time, precursor concentration can be used to control particle size. As the precursor concentration increased from 0.5% to 35% w/w, primary particle diameter increased from 7 ± 2 to 20 ± 11 nm. Larger primary particle diameters were observed in the low gas flow system (set B) due to the long residence time in the high temperature zone. For the dependence of temperature on particle diameter, particles grew to similar diameter, i.e. ∼11 nm, in both flame conditions within the hot temperature zone (80% of melting point of CuO) but for particles having longer residence time, i.e. 550 ms in set B, the standard deviation of particle diameter is 45% larger than for particles with 66 ms as residence time in set A. Modeling gave a result for CuO final particle diameter, based on collision/sintering theory with sintering by solid state diffusion, of 6.7 and 9.0 nm for set A and set B, respectively, with surface tension assumed to be 0.5 J/m 2 .Comparison with the experiment results, 11 ± 4 nm diameter for both flame conditions, indicates the simulations were reasonable.

  • Copper Oxide Nanoparticle made by flame spray pyrolysis for photoelectrochemical water splitting part ii photoelectrochemical study
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Chiaying Chiang, Kosi C Aroh, Nicholas Franso, Vibha R Satsangi, Sahab Dass, Sheryl H Ehrma
    Abstract:

    Abstract A scalable method for hydrogen generation by splitting water via a photoelectrochemical cell was studied. Flame spray pyrolysis and spin coating processing methods were used for preparing Copper Oxide Nanoparticles and Copper Oxide photocathodes. Copper Oxide p-type semiconductor Nanoparticles made by flame spray pyrolysis were spin coated on conducting ITO substrates and served as photocathodes for photoelectrochemical splitting of water. The film thickness was controlled by the concentration of the CuO suspension solution and numbers of layer deposited on the substrate. As sintering temperature increased to 600 °C, crystalline diameter increased from 28 nm (before sintering) to 110 nm and the bandgaps decreased from 1.68 eV to 1.44 eV. A 387 nm thickness CuO film with bandgap 1.44 eV was demonstrated to have 1.48% total conversion efficiency and 0.91% photon-to-hydrogen generation efficiency. The net photocurrent density (photocurrent – dark current) was measured to be 1.20 mA/cm 2 at applied voltage of −0.55 V vs. Ag/AgCl in 1 M KOH electrolyte with 1 sun (AM1.5G) illumination. Based on the Mott–Schottky plot, the carrier density was estimated to be 1.5 × 10 21  cm −3 and the flatband potential to be 0.23 V vs. Ag/AgCl. Furthermore, the valence band edge and conduction band levels were found to lie at −5.00 eV and −3.56 eV respect to the vacuum respectively.

Igor S. Altman - One of the best experts on this subject based on the ideXlab platform.

  • Copper and Copper Oxide Nanoparticle formation by chemical vapor nucleation from Copper ii acetylacetonate
    Journal of Nanoparticle Research, 2001
    Co-Authors: Albert G. Nasibulin, Olivier Richard, Esko I Kauppinen, Petri Ahonen, Igor S. Altman
    Abstract:

    Crystalline nanometer-size Copper and Copper (I) Oxide particle formation was studied by thermal decomposition of Copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of P prec = 0.06 to 44 Pa at furnace temperatures of 431.5°C, 596.0°C, and 705.0°C. Agglomerates of primary particles were formed at P prec0.1 Pa at all temperatures. At 431.5°C the number mean size of the primary particles increased from D p = 3.7 nm (with geometric standard deviation σg = 1.42) to D p = 7.2 nm (σg = 1.33) with the increasing precursor vapor particle pressure from 1.8 to 16 Pa. At 705.0°C the primary particle size decreased from D p = 24.0 nm (σg=1.57) to D p = 7.6 nm (σg = 1.54), respectively. At furnace temperatures of 431.5°C and 596.0°C only crystalline Copper particles were produced. At 705.0°C the crystalline product of the decomposition depended on the precursor vapor pressure: Copper particles were formed at P prec>10 Pa, Copper (I) Oxide at P precleq 1 Pa, and a mixture of the metal and its Oxide at intermediate vapor pressures. A kinetic restriction on Copper particle growth was shown, which leads to the main role of Cu2 molecule participation in the particle formation. The formation of Copper (I) Oxide particles occurs due to the surface reaction of the decomposition products (mainly carbon diOxide). For the explanation of the experimental results, a model is proposed to build a semiempirical phase diagram of the precursor decomposition products.

  • Copper and Copper Oxide Nanoparticle Formation by Chemical Vapor Nucleation From Copper (II) Acetylacetonate
    Journal of Nanoparticle Research, 2001
    Co-Authors: Albert G. Nasibulin, P. Petri Ahonen, Olivier Richard, Esko I Kauppinen, Igor S. Altman
    Abstract:

    Crystalline nanometer-size Copper and Copper (I) Oxide particle formationwas studied by thermal decomposition of Copper acetylacetonate Cu(acac)2 vapor using a vertical flow reactor at ambient nitrogen pressure. The experiments were performed in the precursor vapor pressure range of Pprec = 0.06 to 44Pa at furnace temperatures of 431.5◦ C, 596.0◦C, and 705.0◦ C. Agglomerates of primary particles were formed at Pprec > 0.1Pa at all temperatures. At 431.5◦ C the number mean size of the primary particles increased from Dp = 3.7 nm (with geometric standard deviation σg = 1.42) to Dp = 7.2nm (σg = 1.33) with the increasing precursor vapor particle pressure from 1.8 to 16Pa. At 705.0◦C the primary particle size decreased fromDp = 24.0nm(σg = 1.57) toDp = 7.6nm(σg = 1.54), respectively. At furnace temperatures of 431.5◦ C and 596.0◦ C only crystalline Copper particles were produced. At 705.0◦ C the crystalline product of the decomposition depended on the precursor vapor pressure: Copper particles were formed at Pprec > 10 Pa, Copper (I) Oxide at Pprec ≤ 1Pa, and a mixture of the metal and its Oxide at intermediate vapor pressures. A kinetic restriction on Copper particle growth was shown, which leads to the main role of Cu2 molecule participation in the particle formation. The formation of Copper (I) Oxide particles occurs due to the surface reaction of the decomposition products (mainly carbon diOxide). For the explanation of the experimental results, a model is proposed to build a semiempirical phase diagram of the precursor decomposition products.