@article{arney_fuoco_boltersdorf_maggard_2013, title={Flux Synthesis of Na2Ca2Nb4O13: The Influence of Particle Shapes, Surface Features, and Surface Areas on Photocatalytic Hydrogen Production}, volume={96}, ISSN={["0002-7820"]}, DOI={10.1111/jace.12122}, abstractNote={The layered perovskite (n = 4) Ruddlesden‐Popper phase Na2Ca2Nb4O13 was prepared within molten NaCl and Na2SO4 fluxes, yielding either rod‐shaped or platelet‐shaped particles, respectively. The flux‐to‐reactant molar ratios of 5:1 or 20:1 were found to significantly influence particle sizes and surface areas, while still maintaining the overall particle shapes. Measured surface areas of flux‐prepared Na2Ca2Nb4O13 particles ranged from ∼0.36 to 4.6 m2/g, with the highest surface areas obtained using a 5:1 (NaCl‐to‐Na2Ca2Nb4O13) molar ratio. All samples exhibited a bandgap size of ∼3.3 eV, as determined by UV–Vis diffuse reflectance measurements. Photocatalytic rates for hydrogen production under ultraviolet light for platinized Na2Ca2Nb4O13 particles in an aqueous methanol solution ranged from ∼230 to 1355 μmol H2 g−1 h−1 when using the photochemical deposition (PCD) method of platinization, and ∼113–1099 μmol H2 g−1 h−1 when using the incipient wetness impregnation (IWI) method of platinization. The higher photocatalytic rates were obtained for the rod‐shaped particles with the highest surface areas, with an apparent quantum yield (AQY) measured at ∼6.5% at 350 nm. For the platelet‐shaped particles, the higher photocatalytic rates were observed for the sample with the lowest surface area but the largest concentration of stepped edges and grooves observed at the particle surfaces. The latter origin of the photocatalytic activity is confirmed by the significant enhancement of the photocatalytic rates by the PCD method that allows for the preferential deposition of the surface Pt cocatalyst islands at the stepped edges and grooves, while the photocatalytic enhancement is much smaller when using the more general IWI platinization method.}, number={4}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Arney, David and Fuoco, Lindsay and Boltersdorf, Jonathan and Maggard, Paul A.}, year={2013}, month={Apr}, pages={1158–1162} }
 @article{arney_maggard_2012, title={Effect of Platelet-Shaped Surfaces and Silver-Cation Exchange on the Photocatalytic Hydrogen Production of RbLaNb2O7}, volume={2}, ISSN={["2155-5435"]}, DOI={10.1021/cs200643h}, abstractNote={The layered Dion-Jacobsen RbLaNb2O7 photocatalyst was prepared in platelet-shaped morphologies using a RbCl flux and with a modulation of the particle morphologies using from 1:1–10:1 (RbCl:RbLaNb2O7) molar ratios and reaction times of 24 h–1 h at a temperature of 1100 °C. Further, the silver-ion exchanged AgLaNb2O7 product could be prepared by reaction of the RbLaNb2O7 particles within a AgNO3 flux at 250 °C for 24 h. These products were characterized by powder X-ray diffraction (e.g., Imma, a = 5.4763(8) A, b = 22.4042(2) A, c = 5.1576(3) A, for RbLaNb2O7; I41/acd, a = 7.7803(2) A, c = 42.5692(4) A, for AgLaNb2O7). At a 10:1 flux ratio, rounded-platelet morphologies with smooth surfaces were observed by scanning electron microscopy (SEM) with thicknesses of ∼100–300 nm and lateral dimensions of ∼1.0–6.0 μm. These particle dimensions and morphologies were conserved during the silver-exchange reactions. Photocatalytic rates for hydrogen production were measured in aqueous methanol and yielded maximal rate...}, number={8}, journal={ACS CATALYSIS}, author={Arney, David and Maggard, Paul A.}, year={2012}, month={Aug}, pages={1711–1717} }
 @article{arney_watkins_maggard_2011, title={Effects of Particle Surface Areas and Microstructures on Photocatalytic H-2 and O-2 Production over PbTiO3}, volume={94}, ISSN={["1551-2916"]}, DOI={10.1111/j.1551-2916.2010.04262.x}, abstractNote={The visible-light photocatalyst PbTiO3 was prepared in molten NaCl and PbO fluxes using 0.5:1–20:1 flux-to-reactant molar ratios by heating to 1000°C for a duration of 1 h. Yellow-colored powders were obtained in high purity, as confirmed by powder X-ray diffraction and exhibited a bandgap size of ∼2.75 eV as determined by UV–Vis diffuse reflectance measurements. Roughly spherical and cubic shaped particles with homogeneous microstructures were observed with sizes ranging from ∼100 to 6 000 nm, and surface areas ranging from 0.56 to 2.63 m2/g. The smallest particle-size distributions and highest surface areas were obtained for the 10:1 NaCl flux molar ratio. By comparison, solid-state preparations of PbTiO3 particles exhibit no well-controlled sizes or microstructures. The water-splitting photocatalytic activities of the PbTiO3 particles were evaluated in visible light (λ>420 nm), and yielded maximum rates of 27.4 μmol·H2·(g·h)−1 for the PbTiO3 prepared using a 1:1 PbO molar ratio and 183 μmol·O2·(g·h)−1 for the solid-state prepared sample. The rates were inversely correlated with the particle surface areas. The relationship between particle morphology and photocatalytic activity provides important insights into understanding the origins of photocatalysis in metal-oxides.}, number={5}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Arney, David and Watkins, Tylan and Maggard, Paul A.}, year={2011}, month={May}, pages={1483–1489} }
 @article{arney_hardy_greve_maggard_2010, title={Flux synthesis of AgNbO3: Effect of particle surfaces and sizes on photocatalytic activity}, volume={214}, ISSN={["1010-6030"]}, DOI={10.1016/j.jphotochem.2010.06.006}, abstractNote={The molten-salt flux synthesis of AgNbO3 particles was performed in a Na2SO4 flux using 1:1, 2:1 and 3:1 flux-to-reactant molar ratios and heating to 900 °C for reaction times of 1–10 h. Rectangular-shaped particles are obtained in high purity and with homogeneous microstructures that range in size from ∼100 to 5000 nm and with total surface areas from 0.16 to 0.65 m2 g−1. The smallest particle-size distributions and highest surface areas were obtained for the largest amounts of flux (3:1 ratio) and the shortest reaction time (1 h). Measured optical bandgap sizes of the AgNbO3 products were in the range of ∼2.8 eV. The photocatalytic activities of the AgNbO3 particles for H2 formation were measured in visible light (λ > 420 nm) in an aqueous methanol solution and varied from ∼1.7 to 5.9 μmol H2 g−1 h−1. The surface microstructures of the particles were evaluated using field-emission SEM, and the highest photocatalytic rates of the AgNbO3 particles were correlated with the formation of high densities of ∼20–50 nm terraced surfaces. By comparison, the solid-state sample showed no well-defined morphology or microstructure. Thus, the results presented herein demonstrate the utility of flux-synthetic methods in targeting new particles sizes and surface microstructures for the enhancement and understanding of photocatalytic reactivity over metal-oxide particles.}, number={1}, journal={JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY}, author={Arney, David and Hardy, Christopher and Greve, Benjamin and Maggard, Paul A.}, year={2010}, month={Jul}, pages={54–60} }
 @article{joshi_palasyuk_arney_maggard_2010, title={Semiconducting Oxides to Facilitate the Conversion of Solar Energy to Chemical Fuels}, volume={1}, ISSN={["1948-7185"]}, DOI={10.1021/jz100961d}, abstractNote={The rising significance of producing useful chemical fuels from sunlight has motivated an upsurge of photochemical research, as shown by the growing diversity of chromophores, redox catalysts, and reactivity studies. However, their synergistic integration within artificial photosynthetic systems requires shareable platforms. Early transition-metal oxides have exhibited effective chromophoric/electronic properties across many systems, which has enabled outstanding photocatalytic water splitting efficiencies, but only under ultraviolet irradiation. Semiconducting modifications of these oxides have been investigated that both extend their absorption deep into the visible region and also closely bracket the redox potentials for water splitting and carbon dioxide reduction. Their coupling to surface-anchored molecular catalysts in order to lower kinetic barriers and provide product selectivity is anticipated to lead to studies involving the dynamic interplay of photons, charge carriers, and catalyst turnover.}, number={18}, journal={JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, author={Joshi, Upendra A. and Palasyuk, Andriy and Arney, David and Maggard, Paul A.}, year={2010}, month={Sep}, pages={2719–2726} }
 @article{arney_porter_greve_maggard_2008, title={New molten-salt synthesis and photocatalytic properties of La2Ti2O7 particles}, volume={199}, ISSN={["1010-6030"]}, DOI={10.1016/j.jphotochem.2008.06.005}, abstractNote={The (1 1 0)-layered perovskite La2Ti2O7 photocatalyst has been synthesized in high purities and in homogeneous microstructures within a molten Na2SO4/K2SO4 flux in short reaction times of ∼1–10 h. The La2Ti2O7 particle morphologies and sizes were investigated as a function of flux amounts (flux:La2Ti2O7 molar ratios of 1:1, 2:1, 5:1, and 10:1) and reaction times (1, 2, 5, and 10 h). Powder X-ray diffraction confirmed the structure type and high purity, and UV–vis diffuse reflectance measurements yielded optical bandgap sizes of ∼3.75–3.81 eV. Rectangular platelet morphologies are obtained with maximal dimensions of ∼500–5000 nm, but with thicknesses down to <100 nm, and which decrease in size with increasing amounts of flux used in the synthesis. Photocatalytic activities of the La2Ti2O7 products were measured under ultraviolet irradiation in aqueous methanol solutions and yielded rates for hydrogen production from 55 to 140 μmol H2 h−1 g−1, with the maximum photocatalytic rates for the smallest particles, e.g. for 1:1 and 10:1 flux:La2Ti2O7 ratios respectively. The flux-prepared La2Ti2O7 products were also photocatalytically active in pure deionized water, yielding maximal rates for hydrogen formation of 31 μmol H2 h−1 g−1. The observed photocatalytic rates were up to nearly two times greater than that obtained when La2Ti2O7 was prepared by the reported solid-state method, and indicate that the exposed crystallite edges and the (0 1 0) and (0 0 1) crystal faces play a key role in the photocatalysis mechanisms for hydrogen formation.}, number={2-3}, journal={JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY}, author={Arney, David and Porter, Brittany and Greve, Benjamin and Maggard, Paul A.}, year={2008}, month={Sep}, pages={230–235} }