This Minireview first summarizes the principle of semiconductor photocatalysis focusing on the comparability of photocatalytic activities, a central problem of the field, often leading to unjustified mechanistic conclusions. It then describes the visible light photofixation of pure and aerial nitrogen at a nanostructured Fe₂Ti₂O₇ thin film on glass. In the presence of ethanol or humic acid, ammonia is formed via hydrazine in the photochemical, first reaction part. Since only reducing agents exhibiting a current amplification effect enable ammonia formation, it is proposed that the primary reduction of N₂ is a one‐photon – two‐electron proton‐coupled electron transfer. A consecutive aerial oxidation of ammonia to nitrate constitutes the thermally catalyzed final reaction part, indicating the dual catalysis function of the film. Since the over‐all reaction proceeds also with air, and weathering of corresponding iron titanium minerals could form Fe₂Ti₂O₇ and similar semiconducting surfaces, a solar non‐enzymatic nitrogen fixation by natural reducing agents may occur in nature. This aspect of environmental chemistry is largely unexplored.

中文翻译：

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在光与暗中：钛铁酸半导体薄膜上氮到氨和硝酸盐的光催化固定

本小型回顾首先总结了半导体光催化的原理，重点是光催化活性的可比性，这是该领域的主要问题，通常会导致不合理的机械结论。然后，它描述了在玻璃上的纳米结构Fe ₂ Ti ₂ O ₇薄膜上，纯净氮和空气氮的可见光固色作用。在乙醇或腐植酸的存在下，氨在光化学反应的第一部分通过肼形成。由于只有表现出电流放大作用的还原剂才能形成氨，因此建议N ₂的一次还原是单光子–两电子质子耦合电子转移。氨不断地空中氧化为硝酸盐构成了热催化的最终反应部分，表明了膜的双重催化功能。由于总体反应也与空气一起进行，相应的铁钛矿物质的风化会形成Fe ₂ Ti ₂ O ₇和类似的半导体表面，因此自然界中可能会发生天然还原剂对太阳的非酶固氮作用。环境化学的这一方面在很大程度上尚待探索。