Herein, we used a hydrothermal method and calcination at different temperatures to synthesize Ca₂Nb₂O₇ composite oxides with two different sub-crystalline phases, namely perovskite and pyrochlore. From the photocatalytic degradation of tetracycline, the catalytic activity of the pyrochlore crystalline phase is higher than that of the perovskite crystalline phase. This is because the pyrochlore phase structure is more disordered, which has abundant oxygen vacancies and can generate more ·O₂⁻, h⁺, and ·OH under visible light irradiation. Additionally, it has a smaller bandgap and a lower valence band energy. The combination of these factors enables the higher reaction activity of the pyrochlore phase structure compared with the perovskite crystalline phase.

中文翻译：

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钙钛矿和烧绿石亚晶相 Ca2Nb2O7 复合氧化物可见光降解四环素

在此，我们采用水热法和不同温度的煅烧合成了具有两种不同亚晶相的Ca ₂ Nb ₂ O ₇复合氧化物，即钙钛矿和烧绿石。从四环素的光催化降解来看，烧绿石晶相的催化活性高于钙钛矿晶相。这是因为烧绿石相结构较为无序，具有丰富的氧空位，在可见光照射下能产生更多的·O ₂ ^-、h ⁺和·OH。此外，它具有较小的带隙和较低的价带能量。这些因素的结合使得烧绿石相结构比钙钛矿晶相具有更高的反应活性。