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Improving visible light photocatalytic activity of NaNbO3: a DFT based investigation

机译：改善纳沃3的可见光光催化活性：基于DFT的调查

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摘要

Depleting sources of fossil fuels and their adverse environmental impact drive global interest to find efficient materials for hydrogen generation through solar water splitting. Although, NaNbO3 has several key features as an efficient photocatalyst, its large band gap restricts its photoactivity only in the UV-region of the solar spectrum. In this theoretical study, we investigate the effect of doping on the electronic structure of NaNbO3 aiming at improving its visible light photocatalytic activity. For this purpose, we employ hybrid density functional theory (DFT), which successfully reproduces the experimental band gap of NaNbO3. Doping with N has been found to reduce the effective band gap significantly by introducing localized acceptor states which however are known to promote the electron hole recombination rate. To overcome this, we propose codoping with W at the Nb lattice site. Interestingly this completely passivates those localized acceptor states. The band gap is found to be sufficiently reduced to enhance the visible light activity. The present strategy reduces the band gap in such a controlled way that (W, N)NaNbO3 satisfies the thermodynamic criteria to execute the overall decomposition of H2O, indicated in the relative position of its band edges with respect to water redox levels. Moreover, doping of N is found to be facilitated in the presence of W due to reduction in formation energy. Additionally, spontaneous formation of charge compensated valence defects is expected to be reduced in the presence of the (W, N) pair in comparison to individual dopant elements due to maintaining the total electrical charge neutrality.
机译：化石燃料的耗尽来源及其不利的环境影响驱动全球兴趣通过太阳能分裂来寻找氢气的有效材料。尽管Nanbo3具有若干关键特征，作为高效的光催化剂，其大带隙仅在太阳光谱的UV区域中限制其光度。在这个理论研究中，我们研究了掺杂对旨在改善其可见光光催化活性的纳米电子结构的影响。为此目的，我们采用混合密度泛函理论（DFT），其成功地再现了NaNBO3的实验带隙。已经发现掺杂N通过引入局部受体状态而显着降低有效带隙，然而已知促进电子空穴重组率。为了克服这一点，我们建议在NB格子网站上用W.有趣的是，这完全钝化了那些本地化的受体国家。发现带隙充分降低以增强可见光活性。本策略以这种受控方式减少了带隙，即（W，N）纳米3满足热力学标准，以执行H2O的总分解，其在其带状边缘相对于水氧化还原水平的相对位置。此外，由于形成能量的还原，发现在W存在下促进n的掺杂。另外，与单独的掺杂剂元件相比，由于保持总电荷中位而相比，预期电荷补偿价缺陷的自发形成。

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  • 来源
    《RSC Advances》 |2016年第93期|共9页
  • 作者

    Modak Brindaban; Modak Pampa; Ghosh Swapan K.;

  • 作者单位

    Bhabha Atom Res Ctr Theoret Chem Sect Bombay 400085 Maharashtra India;

    Atom Energy Regulatory Board Radiol Safety Div Bombay 400094 Maharashtra India;

    Bhabha Atom Res Ctr Theoret Chem Sect Bombay 400085 Maharashtra India;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
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