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    ABSTRACT: Solar generation of fuel is a promising future energy technology, and strong acidic conditions are highly desirable for integrated solar hydrogen generators. In particular, water splitting near pH 0 is attractive due to the availability of high theoretical efficiency, high performance hydrogen evolution catalysts, and robust ion exchange membranes. The lack of a stable, earth-abundant oxygen evolution catalyst inhibits deployment of this technology, and development of such a material is hampered by the strong anti-correlation between electrochemical stability and catalytic activity of non-precious metal oxides. High-throughput screening of mixed metal oxides offers a promising route to the identification of new stable catalysts and requires careful design of experiments to combine the concepts of rapid experimentation and long-term stability. By combining serial and parallel measurement techniques, we have created a high-throughput platform to assess the catalytic activity of material libraries in the as-prepared state and after 2 h of operation. By screening the entire (Mn-Co-Ta-Sb)O x composition space, we observe that the compositions with highest initial activity comprised cobalt and manganese oxides, but combinations with antimony and tantalum offer improved stability. By combining the desired properties of catalytic activity and stability, the optimal composition regions are readily identified, demonstrating the success and fidelity of this novel high-throughput screening platform.
    03/2014; 6(2):229-236. DOI:10.1007/s12678-014-0237-7
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    ABSTRACT: A series of 10 mol% Cu/TiO2 photocatalysts were prepared by varying H2O:alkoxide molar ratios (8, 16, 32, and 64) using sol–gel associated hydrothermal method. The influence of hydrolysis rate was investigated on the physicochemical properties and photocatalytic hydrogen production by water photosplitting in an aqueous NaOH-glycerol solution. The photocatalyst characterizations were performed using thermogravimetric analysis (TGA), temperature-programmed reduction (TPR), x-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS), and diffuse reflectance UV–Vis spectroscopy (DR-UV-Vis). It was found that photocatalyst with the H2O:alkoxide molar ratio of 32 produce the highest cumulative hydrogen production among all synthesized photocatalysts. Its produced hydrogen reached up to 10571 μmol in 300 min of reaction in the aqueous NaOH-glycerol solution compared with aqueous NaOH and glycerol solutions separately. The highest photocatalytic performance can be attributed to good crystallinity, wide range visible absorption, lower bandgap energy and coexistence of Cu2O and CuO together. Furthermore, the synergetic effect of glycerol and hydroxyl groups in reaction medium enhanced the photooxidation of glycerol, reduced the deactivation of the photocatalysts and the backward reaction of O2 and H2 resulting in higher hydrogen production.
    International Journal of Hydrogen Energy 05/2015; 40(18). DOI:10.1016/j.ijhydene.2015.03.019 · 2.93 Impact Factor
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    ABSTRACT: Plasmonic nanostructures have played a significant role in the development of modern materials science and technology. Plasmon-enhanced solar light harvesting to enhance the efficiency of solar to fuel energy conversion has been one of the most important research areas of the last decade to help meet the worlds growing energy demand. Over the years, both organic and inorganic semiconductor materials, with high stability, environmental compatibility and photocatalytic activity, have been widely used as photocatalysts for direct conversion of solar energy into fuels. However, the efficiency of semiconductors is limited by their inability to absorb visible light due to high band gap. During last few years, great amount of research has been carried out to improve the efficiency of photocatalysts and photovoltaic devices by integration of plasmonic nanoparticles (NPs) with semiconductor materials. The presence of plasmonic NPs leads to increase in the absorption cross-section of semiconductors via strong field enhancement, extension of light absorption to longer wavelengths and enhances electron-hole charge separation in semiconductor medium, thus maximize the efficiency of photocatalytic and photovoltaic devices. In this review, we summarize recent advances made toward the integration of plasmonic nanostructures with semiconductor photocatalytic systems for enhanced light harvesting applications, including dye degradation, water splitting for H2 generation, photodynamic therapy, chemical transformation and photovoltaics.
    RSC Advances 01/2015; 5(37):29076-29097. DOI:10.1039/C5RA01819F · 3.71 Impact Factor

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Jun 2, 2014