In this work, the kinetics and mechanisms of photocatalytic degradation of perfluorooctanoic acid (PFOA) by nitrogen-doped indium trioxide (N-doped In₂O₃ or NH₄NO₃-In₂O₃) under Xe lamp irradiation were systematically investigated. Nitrogen originating from various inorganic and organic nitrogen compounds was doped into In₂O₃ to examine the catalytic effect. The NH₄NO₃-In₂O₃ catalyst was characterized by SEM, TEM, FT-IR, UV-DRS, BET surface area, XPS, and XRD, and showed the best catalytic performance. After 18 h of irradiation, PFOA was almost completely degraded with addition of 5 mg catalyst, while it was hardly degraded by simulated sunlight alone. The low photocatalytic degradation efficiency of PFOA was observed in different natural waters, which was due to the inhibitory effect of high pH and common anions like SO₄²⁻. The calculation results of Materials Studio showed that a shoulder-to-shoulder π system between nitrogen atom and oxygen atom (NO π*) was formed after nitrogen doping into interstitial sites of In₂O₃, therefore resulting in a reduction in band gap energy. Occupied NO π* states were responsible for the red shift, while unoccupied NO π* levels restrained the recombination of electrons (e⁻) and holes (h⁺). Nitrogen doping reduced the excitation energy for electronic transition, and thus accelerated the reaction. According to mass spectrometry analysis, decarboxylation and elimination were still the main photodegradation pathways of PFOA. To the best of our knowledge, this report is the first to explore the reaction mechanisms of PFOA in an N-doped In₂O₃/Xe lamp irradiation system.

在这项工作中，系统研究了在氙灯照射下氮掺杂三氧化铟（N掺杂In ₂ O ₃或NH ₄ NO ₃ -In ₂ O _{3 ）光催化降解全氟辛酸（PFOA）的动力学和机理。}来自各种无机和有机氮化合物的氮被掺杂到In ₂ O ₃中以检查催化效果。NH ₄ NO ₃ -In ₂ O ₃采用SEM、TEM、FT-IR、UV-DRS、BET比表面积、XPS和XRD对催化剂进行了表征，表现出最好的催化性能。辐照 18 h 后，加入 5 mg 催化剂后 PFOA 几乎完全降解，而仅通过模拟阳光几乎不降解。_{在不同的天然水中观察到PFOA的光催化降解效率较低，这是由于高pH值和常见阴离子如SO 4} ^2-的抑制作用。Materials Studio的计算结果表明，氮掺杂到In ₂ O _{3的间隙位点后，形成了氮原子和氧原子（NO π*）的肩对肩π体系。}，因此导致带隙能量降低。被占据的 NO π* 状态是造成红移的原因，而未被占据的 NO π* 能级抑制电子 (e ^- ) 和空穴 (h ⁺ ) 的复合。氮掺杂降低了电子跃迁的激发能，从而加速了反应。质谱分析表明，脱羧和消除仍是PFOA的主要光降解途径。据我们所知，本报告首次探索了 PFOA 在 N 掺杂的 In ₂ O ₃ /Xe 灯辐照系统中的反应机理。