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首页> 外文学位 >Surface modification and chemistry of hematite-based catalysts for water oxidation: Model surfaces, nanomaterials, and thin films.
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Surface modification and chemistry of hematite-based catalysts for water oxidation: Model surfaces, nanomaterials, and thin films.

机译：用于水氧化的赤铁矿基催化剂的表面改性和化学性质：模型表面，纳米材料和薄膜。

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摘要

Hematite-based electrocatalysts are widely used for water oxidation, but these catalysts suffer from its low reaction kinetics. To help elucidate detailed reaction mechanisms associated with water oxidation, water chemisorption and reaction as well as structural changes induced by Ni incorporation into the alpha-Fe2O3(0001) surface was studied. Incorporation of Ni into the near-surface region of hematite changes the structure of the (0001) surface by the formation of FeO-like domains on the topmost layer. Electrochemical measurements demonstrated that Ni incorporation leads to higher current density and lower onset potential than the unmodified alpha-Fe 2O3 surface.;To extend the surface science study to real catalysts, hematite nanocrystals were synthesized with continuous tuning of the aspect-ratio and fine control of the surface area ratio (from 98% to 30%) of the (0001) facet with respect to other surfaces. Ni doping forms a uniformly doped NixFe 2-xO3 surface overlayer that improves the electrocatalytic activity of water oxidation. The enhancement of water oxidation activity by Ni-doping increased as the surface area ratio of the (0001) facet of hematite nanocrystals increased, consistent with the theoretical predictions and surface science studies.;Then, a composite oxide film photoelectrode comprised of alpha-Fe 2O3 and WO3 were prepared, and exhibited a water oxidation photocurrent onset potential as low as 0.43 V vs. RHE. This result represents one of the lowest onset potentials measured for hematite-based PEC water oxidation systems. The composition of the films differs between the surfaces and bulk, with tungsten found to be concentrated in the surface region. Post-reaction Raman spectroscopy characterization demonstrates that water interacts with surface WO3 crystals, an event that is associated with the formation of a hydrated form of the oxide.;Lastly, the surface chemistry of H2O on hematite nanoplates is investigated by studying water adsorption and desorption behavior via ATR-FTIR, then correlating it with the surface chemistry study on hematite model surfaces. By adapting the specular reflectance geometry, hematite nanoplates were incorporated into a spectroelectrochemistry setup to simultaneously evaluate electrode performance and monitor the evolution of surface-bound species as a function of applied potential, which are consistent with the surface science studies mentioned above.
机译：赤铁矿基电催化剂广泛用于水氧化，但是这些催化剂的反应动力学低。为帮助阐明与水氧化，水的化学吸附和反应以及镍掺入α-Fe2O3（0001）表面引起的结构变化有关的详细反应机理。通过在最上层形成FeO样畴，将Ni掺入赤铁矿的近表面区域中，改变了（0001）表面的结构。电化学测量表明，与未改性的α-Fe2O3表面相比，掺入Ni会导致更高的电流密度和更低的起始电势。为了将表面科学研究扩展到实际催化剂，合成了赤铁矿纳米晶，并不断调整了长宽比和精细控制（0001）小平面的表面积相对于其他表面的表面积比（从98％到30％）。 Ni掺杂形成均匀掺杂的NixFe 2-xO3表面覆盖层，可改善水氧化的电催化活性。随着赤铁矿纳米晶体（0001）晶面表面积比的增加，Ni掺杂对水氧化活性的增强作用增强，这与理论预测和表面科学研究相一致;然后，由α-Fe组成的复合氧化物膜光电极制备了2O3和WO3，并且相对于RHE，其显示出低至0.43V的水氧化光电流起始电势。该结果代表了基于赤铁矿的PEC水氧化系统测得的最低起始电位之一。膜的组成在表面和体积之间有所不同，发现钨集中在表面区域。反应后拉曼光谱表征表明水与表面WO3晶体相互作用，这与氧化物水合形式的形成有关。最后，通过研究水的吸附和解吸研究了H2O在赤铁矿纳米板上的表面化学性质。通过ATR-FTIR的行为，然后将其与赤铁矿模型表面的表面化学研究相关联。通过调整镜面反射几何形状，将赤铁矿纳米板结合到光谱电化学装置中，以同时评估电极性能并监测表面结合物种随施加电势的变化，这与上述表面科学研究一致。

著录项

  • 作者

    Zhao, Peng.;

  • 作者单位

    Princeton University.;

  • 授予单位 Princeton University.;
  • 学科 Materials science.;Inorganic chemistry.;Physical chemistry.;Nanotechnology.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 169 p.
  • 总页数 169
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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