The search for suitable materials for solar water splitting is addressed with combinatorial material science methods. Thin film Fe–V–O materials libraries were synthesized using combinatorial reactive magnetron cosputtering and subsequent annealing in air. The design of the libraries comprises a combination of large compositional gradients (from Fe₁₀V₉₀O_x to Fe₇₉V₂₁O_x) and thickness gradients (from 140 to 425 nm). These material libraries were investigated by high-throughput characterization techniques in terms of composition, structure, optical, and photoelectrochemical properties to establish correlations between composition, thickness, crystallinity, microstructure, and photocurrent density. Results show the presence of the Fe₂V₄O₁₃ phase from ∼11 to 42 at. % Fe (toward low-Fe region) and the FeVO₄ phase from ∼37 to 79 at. % Fe (toward Fe-rich region). However, as a third phase, Fe₂O₃ is present throughout the compositional gradients (from low-Fe to Fe-rich region). Material compositions with increasing crystallinity of the FeVO₄ phase show enhanced photocurrent densities (∼160 to 190 μA/cm²) throughout the thickness gradients whereas compositions with the Fe₂V₄O₁₃ phase show comparatively low photocurrent densities (∼28 μA/cm²). The band gap energies of Fe–V–O films were inferred from Tauc plots. The highest photocurrent density of ∼190 μA/cm² was obtained for films with ∼54 to 66 at. % Fe for the FeVO₄ phase with ∼2.04 eV for the indirect and ∼2.80 eV for the direct band gap energies.

中文翻译：

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用于太阳能水分解的Fe–V–O薄膜材料库的组合合成和高通量表征

通过组合材料科学方法解决了寻找适合用于太阳能水分解的材料的问题。薄膜Fe–V–O材料库是使用组合反应磁控共溅射和随后在空气中退火的方法合成的。库的设计包括大的成分梯度（从Fe ₁₀ V ₉₀ O _x到Fe ₇₉ V ₂₁ O _{x）的组合}厚度梯度（从140到425 nm）。通过高通量表征技术对这些材料库进行了成分，结构，光学和光电化学性质方面的研究，以建立成分，厚度，结晶度，微结构和光电流密度之间的相关性。结果表明Fe ₂ V ₄ O ₁₃相存在于〜11至42 at。％Fe（向低Fe区域）和FeVO ₄相从约37至79 at。％Fe（向富铁区域）。然而，作为第三相，Fe ₂ O ₃存在于整个组成梯度中（从低铁到富铁区域）。FeVO ₄结晶度增加的材料成分相在整个厚度梯度中显示出增强的光电流密度（〜160至190μA/ cm ²），而具有Fe ₂ V ₄ O ₁₃相的组合物显示出相对较低的光电流密度（〜28μA/ cm ²）。Fe–V–O薄膜的带隙能是根据Tauc曲线得出的。对于具有约54至66at。％的膜，获得了约190μA/ cm ²的最高光电流密度。FeVO ₄相的％Fe，间接带隙能约为2.04 eV，直接带隙能约为2.80 eV。