Nitrate in wastewater streams causes eutrophication, and nitrate removal is of great importance for environmental protection. Electrochemical nitrate reduction has the advantage of directly converting nitrate to benign or useful chemicals, but it typically requires a considerable overpotential. In this study, photoelectrochemical nitrate reduction is investigated using a Cu₂O photocathode, where photoexcited electrons in the conduction band inherently have an overpotential of >1.6 V for nitrate reduction. The Cu₂O photocathode is found to reduce nitrate to nitrite selectively with a high Faradaic efficiency (>85%). More importantly, as the surface of Cu₂O is particularly catalytic for nitrate reduction, nitrate reduction on Cu₂O kinetically suppresses photocorrosion of Cu₂O without the need for additional catalyst or protection layers. In addition to nitrate reduction, nitrite reduction on Cu₂O is examined to compare the effects of nitrate and nitrite reduction kinetics on the photocurrent generation and photocorrosion of Cu₂O photocathodes.

中文翻译：

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使用 Cu2O 光电阴极光电化学还原硝酸盐和亚硝酸盐

废水中的硝酸盐会造成富营养化，去除硝酸盐对于环境保护具有重要意义。电化学硝酸盐还原的优点是直接将硝酸盐转化为良性或有用的化学品，但它通常需要相当大的过电势。在本研究中，使用 Cu ₂ O 光电阴极研究了光电化学硝酸盐还原，其中导带中的光激发电子固有地具有 >1.6 V 的硝酸盐还原超电势。人们发现Cu ₂ O 光电阴极可以选择性地将硝酸盐还原为亚硝酸盐，并具有高法拉第效率 (>85%)。更重要的是，由于Cu ₂ O的表面对于硝酸盐还原特别具有催化作用，因此Cu ₂ O上的硝酸盐还原在动力学上抑制了Cu ₂ O的光腐蚀，而不需要额外的催化剂或保护层。除了硝酸盐还原之外，还研究了 Cu _{2 O 上的亚硝酸盐还原，以比较硝酸盐和亚硝酸盐还原动力学对 Cu 2} O光阴极的光电流产生和光腐蚀的影响。