The sintering temperature of solid-state synthesis exceeds 1000 ℃, which easily leads to the formation of oxygen vacancies. The presence of oxygen vacancies can alter the electronic/crystal structure and surface chemical properties of perovskite oxides. In this work, the content of oxygen vacancy of NaNbO₃ are controlled by adjusting the heat treatment conditions including atmosphere, temperature, and time. XPS and EPR are used to analyze the relative content of oxygen vacancies. The N₂ heat treatment time is 3 hours, and as the temperature increases from 300 ℃ to 900 ℃, the oxygen vacancy content increases from 16.4% to 18.9%. At 900 ℃, the time is extended to 5 hours, and the oxygen vacancy content increased to 26.4%. The disordered outer structure in HRTEM images confirms the existence of oxygen vacancies. The effect of the presence of oxygen vacancy on the efficiency of piezocatalysis and piezo-photocatalysis of NaNbO₃ is cleared. The NaNbO₃ sample heat-treated in N₂ for 3 hours (named NN-3h N₂) showed the best piezo-photocatalytic performance, with a rate constant (k) of 0.19175 min^-1, which is much higher than the unmodified NaNbO₃ (0.11777 min^-1). The electrochemical test results show that the NN-3h N₂ sample has better charge transfer ability and stronger photocurrent response, indicating that the presence of oxygen vacancies improves the migration and transfer efficiency of charge carriers. The volcanic trend indicates that an appropriate oxygen vacancy content is beneficial to the improvement of piezo-photocatalytic performance.

中文翻译：

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通过控制 NaNbO3 粉末的氧空位含量提高压电光催化活性


固态合成的烧结温度超过1000°C，容易导致氧空位的形成。氧空位的存在会改变钙钛矿氧化物的电子/晶体结构和表面化学性质。在本工作中，通过调整气氛、温度和时间等热处理条件来控制 NaNbO₃ 的氧空位含量。XPS 和 EPR 用于分析氧空位的相对含量。N₂ 热处理时间为 3 小时，随着温度从 300 °C 升高到 900 °C，氧空位含量从 16.4% 增加到 18.9%。在 900 °C 时，时间延长至 5 h，氧空位含量增加到 26.4%。HRTEM 图像中无序的外部结构证实了氧空位的存在。氧空位的存在对 NaNbO₃ 的压电催化和压电光催化效率的影响被清除。在 N₂ 中热处理 3 h 的 NaNbO₃ 样品 （命名为 NN-3h N₂） 表现出最佳的压电光催化性能，速率常数 （k） 为 0.19175min-1，远高于未改性的 NaNbO₃ （0.11777min-1）。电化学测试结果表明，NN-3h N₂ 样品具有较好的电荷转移能力和更强的光电流响应，表明氧空位的存在提高了电荷载流子的迁移和转移效率。火山趋势表明，适当的氧空位含量有利于压电光催化性能的改善。