A novel heterogeneous photocatalyst Ca_xH_4-xSi₄W₁₂O₄₀/Ca₂Ta₂O₇ was prepared by planting silicotungstic acid on the surface of calcium tantalate. The materials are characterized by X-ray diffraction (XRD), scanning electron microspectroscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transformation infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (UV–vis), Energy-dispersive X-ray spectroscopy (EDS), BET surface area, and Malvern ZEN3690 Particle Analyzer (ZP). The results recovered Ca₂Ta₂O₇ presented regular octahedron morphology with the cubic phase structure, and H₄Si₄W₁₂O₄₀ uniformly grew on the surface of Ca₂Ta₂O₇ with the form of Ca_xH_4-xSi₄W₁₂O₄₀. The primary Keggin structures of H₄Si₄W₁₂O₄₀ was found to remain intact as noticed by XRD and FTIR. The modification of H₄Si₄W₁₂O₄₀ on Ca₂Ta₂O₇ surface contributed the increase in negative zeta potential and red shifts. The as-prepared catalyst exhibited greatly enhanced UV photocatalytic efficiency in the reduction of Cr(VI) ions as high as 94.6% under the optimum conditions (Ca₂Ta₂O₇ to H₄Si₄W₁₂O₄₀ was 1:2). Moreover, the composite presented an excellent reusability, which was mainly ascribed to the locally formation of water-insoluble Ca_xH_4-xSi₄W₁₂O₄₀. A probable mechanism involved in the enhanced reducible activity and well recycled performance via CaO binding linkage of H₄Si₄W₁₂O₄₀ and Ca₂Ta₂O₇ is proposed by DFT simulation. This work will be significant in the design of heteropoly acid as stable heterogeneous photocatalyst applied to heavy metal ions reduction.

通过在钽酸钙表面种植硅钨酸，制备了新型的非均相光催化剂Ca _x H _4-x Si ₄ W ₁₂ O ₄₀ / Ca ₂ Ta ₂ O ₇。这些材料的特征在于X射线衍射（XRD），扫描电子显微镜（SEM），X射线光电子能谱（XPS），傅里叶变换红外光谱（FTIR），UV-可见漫反射光谱（UV-vis），能源色散X射线光谱（EDS），BET表面积和Malvern ZEN3690粒子分析仪（ZP）。结果回收了Ca ₂ Ta ₂ O ₇H ₄ Si ₄ W ₁₂ O ₄₀具有立方相结构的规则八面体形态，并且在Ca ₂ Ta ₂ O ₇表面上以Ca _x H _4-x Si ₄ W ₁₂ O ₄₀的形式均匀生长。XRD和FTIR发现，H ₄ Si ₄ W ₁₂ O ₄₀的一级Keggin结构保持完整。H ₂ Si ₄ W ₁₂ O ₄₀在Ca ₂上的改性Ta ₂ O ₇表面有助于负ζ电势的增加和红移。在最佳条件下（Ca ₂ Ta ₂ O ₇至H ₄ Si ₄ W ₁₂ O ₄₀为1：2），所制备的催化剂在还原Cr（VI）离子方面显示出大大提高的UV光催化效率，高达94.6％。。此外，该复合材料具有极好的可重复使用性，这主要归因于局部形成水不溶性Ca _x H _4-x Si ₄ W ₁₂ O ₄₀。通过DFT模拟，提出了通过H ₄ Si ₄ W ₁₂ O ₄₀和Ca ₂ Ta ₂ O _7的Ca O结合键增强还原活性和良好循环利用性能的可能机理。这项工作对于杂多酸的设计具有重要意义，因为杂多酸是一种稳定的均相光催化剂，可用于重金属离子的还原。