BaTiO3 纳米晶体中的铁电极化控制光电化学水氧化和光催化析氢,Journal of the American Chemical Society

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BaTiO3 纳米晶体中的铁电极化控制光电化学水氧化和光催化析氢
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-08-16 , DOI: 10.1021/jacs.3c03762
Samutr Assavachin ₁ , Frank E Osterloh ₁

Affiliation

铁电 (FE) 半导体（例如 BaTiO _3）在施加电场后支持残余极化，从而促进光生电荷载流子的分离。在这里，我们首次展示了钛酸钡纳米晶体的有限元增强光催化析氢和光电化学水氧化。通过水热合成TiO ₂和氢氧化钡获得了铁电四方结构类型的纳米晶体，产率为63%。钽基板上的BaTiO ₃纳米晶体薄膜在紫外光 (60 mW cm ^–2 ) 照射下在 1.23 V RHE 下表现出 0.141 mA cm ^{–2的水氧化光电流。}垂直于薄膜平面的52.8 kV cm ^–1电极化会使光电流增加 2 倍或减少 3.5 倍，具体取决于场极性。它还将起始电位移动 -0.15 或 +0.09 V，并修改表面光电压信号。最后，暴露在电场下使Pt/BaTiO _3的H₂析出速率提高约1.5倍，并且提高了银在纳米晶体的(001)面上光沉积的选择性。_{所有 FE 增强都可以通过将样品加热到 BaTiO 3}的居里温度以上来消除。这些发现可以通过有限元偶极子引起的材料空间电荷层电势降的变化来解释。利用铁电效应增强氢析出和水氧化的能力对于开发用于燃料转换系统的改进太阳能具有潜在意义。

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Ferroelectric Polarization in BaTiO3 Nanocrystals Controls Photoelectrochemical Water Oxidation and Photocatalytic Hydrogen Evolution

Ferroelectric (FE) semiconductors such as BaTiO₃ support a remnant polarization after the application of an electric field that can promote the separation of photogenerated charge carriers. Here, we demonstrate FE-enhanced photocatalytic hydrogen evolution and photoelectrochemical water oxidation with barium titanate nanocrystals for the first time. Nanocrystals of the ferroelectric tetragonal structure type were obtained by a hydrothermal synthesis from TiO₂ and barium hydroxide in 63% yield. BaTiO₃ nanocrystal films on tantalum substrates exhibit water oxidation photocurrents of 0.141 mA cm^–2 at 1.23 V RHE under UV light (60 mW cm^–2) illumination. Electric polarization at 52.8 kV cm^–1 normal to the film plane increases the photocurrent by a factor of 2 or decreases it by a factor of 3.5, depending on the field polarity. It also shifts the onset potential by −0.15 or +0.09 V and it modifies the surface photovoltage signal. Lastly, exposure to an electric field increases the H₂ evolution rate of Pt/BaTiO₃ by a factor of ∼1.5, and it raises the selectivity of photodeposition of silver onto the (001) facets of the nanocrystal. All FE enhancements can be removed by heating samples above the Curie temperature of BaTiO₃. These findings can be explained by FE dipole-induced changes to the potential drop across the space charge layer of the material. The ability to use the ferroelectric effect to enhance hydrogen evolution and water oxidation is of potential interest for the development of improved solar energy for fuel conversion systems.

更新日期：2023-08-16

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