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首页> 外文期刊>Energy & environmental science >Use of potential determining ions to control energetics and photochemical charge transfer of a nanoscale water splitting photocatalys
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Use of potential determining ions to control energetics and photochemical charge transfer of a nanoscale water splitting photocatalys

机译：使用势能决定离子控制纳米级水分解光催化剂的能量和光化学电荷转移

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摘要

Tetrabutylammonium (TBA) stabilized H[Ca_2Nb_3O_(10)] nanosheets catalyze hydrogen evolution from aqueous methanol under illumination with UV light. Here we show that surface treatment with protons, potassium, and strontium potential-determining cations (PDIs) in aqueous solution modifies the electrostatic, energetic and photocatalytic properties of this nanomaterial. Attachment of cations to the nanocrystals was verified with elemental dispersive spectroscopy. Zeta potentials were measured as -40 mV (TBA+, pH = 4.8), -50 mV (K~+, pH = 4.3), and -20 mV (Sr~(2+), pH = 4.4). Photoelectrochemical measurements in methanol containing 0.1 M tetraethylammonium chloride revealed anodic current photoonset potentials/Fermi energies ranging between -0.59 V (Sr~(2+)) and -0.71 V (at pH = 7, vs. NHE). The photocatalytic proton reduction ability of the modified nanocrystals was assessed in aqueous methanol at pH = 1. Here, K_xH_(1-x)[Ca_2Nb_3O_(10)] evolved hydrogen at 350 μmol H_2 h~(-1), Sr_xH_(1-2x)[Ca_2Nb_3O_(10)l at 70 μmol H_2 h~(-1), and H[Ca_2Nb_3O_(10)] at 160 μmol H_2 h~(-1). In addition, the photocatalytic activity was found to increase (20-160 μmol H_2 h~(-1)) with solution pH. These observed activity variations can be quantitatively understood using a linear free energy relationship between the proton reduction rate constant and the free energy of proton reduction. This shows that the photocatalytic activity of the nanocrystals depends on the electrochemical potentials/Fermi energies of the modified catalysts. The effect of the PDI charge on the nanomaterial energetics can be rationalized by considering the surface potential. The latter can be related to the particle surface charge and the concentration of counterions in solution using the Grahame equation. These results provide a quantitative basis for the understanding and manipulation of nanomateriat photocatalysts with PDIs.
机译：四丁基铵（TBA）稳定的H [Ca_2Nb_3O_（10）]纳米片在紫外光照射下催化甲醇水溶液中的氢释放。在这里，我们表明，在水溶液中用质子，钾和锶电势决定性阳离子（PDI）进行表面处理会改变这种纳米材料的静电，能量和光催化性能。通过元素色散光谱法证实了阳离子与纳米晶体的附着。 Zeta电位的测量值为-40 mV（TBA +，pH = 4.8），-50 mV（K〜+，pH = 4.3）和-20 mV（Sr〜（2+），pH = 4.4）。在含有0.1 M四乙基氯化铵的甲醇中进行的光电化学测量显示，阳极电流的光子定势/费米能介于-0.59 V（Sr〜（2+））和-0.71 V之间（在pH = 7时，相对于NHE）。在pH = 1的甲醇水溶液中评估了改性纳米晶体的光催化质子还原能力。此处，K_xH_（1-x）[Ca_2Nb_3O_（10）]在350μmolH_2 h〜（-1），Sr_xH_（1-在70μmolH_2 h〜（-1）时2x）[Ca_2Nb_3O_（10）l和在160μmolH_2 h〜（-1）时的H [Ca_2Nb_3O_（10）]。另外，发现随着溶液pH值的增加，光催化活性增加（20-160μmolH_2 h〜（-1））。这些观察到的活性变化可以使用质子还原速率常数和质子还原自由能之间的线性自由能关系来定量地理解。这表明纳米晶体的光催化活性取决于改性催化剂的电化学势/费米能。通过考虑表面电势，可以合理化PDI电荷对纳米材料高能学的影响。后者可以与颗粒表面电荷和使用Grahame方程的溶液中抗衡离子的浓度有关。这些结果为理解和处理具有PDI的纳米材料光催化剂提供了定量基础。

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  • 来源
    《Energy & environmental science》 |2014年第2期|736-743|共8页
  • 作者

    Rachel L. Chamousis; Frank E. Osterloh;

  • 作者单位

    Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA;

    Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA;

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