Guo Yanjun, Yang Minjun, Xie Ruo-Chen, Compton Richard G
Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
Chem Sci. 2020 Nov 6;12(1):397-406. doi: 10.1039/d0sc04295a.
The oxygen reduction reaction (ORR) at neutral pH in various aqueous chloride-containing solutions was investigated voltammetrically. In particular, the ORR was performed in high chloride containing aqueous media including authentic and synthetic seawater under oxygen saturated conditions and compared with that in aqueous nitrate and perchlorate media. The experimental voltammograms revealed a two-electron process forming hydrogen peroxide in low chloride media. In contrast, high concentration chloride solutions, including both synthetic and authentic seawater showed an increase of overpotential, accompanied by a splitting of the voltammetric peak into two one-electron features indicating the formation of superoxide in the first step and its release from the silver-solution interface. The implications for silver nanoparticle toxicology are discussed given the markedly greater toxicity of superoxide over peroxide and the high levels of chloride in biological media as well as in seawater.
采用伏安法研究了在各种含氯化物的水溶液中，中性pH条件下的氧还原反应（ORR）。具体而言，在含高浓度氯化物的水介质（包括天然海水和人工合成海水）中，于氧气饱和条件下进行ORR，并与在硝酸盐水溶液和高氯酸盐水溶液中的情况进行比较。实验伏安图显示，在低氯化物介质中，氧还原反应通过两电子过程生成过氧化氢。相比之下，包括人工合成海水和天然海水在内的高浓度氯化物溶液显示出过电位增加，同时伏安峰分裂为两个单电子特征峰，这表明第一步生成了超氧化物，且超氧化物从银-溶液界面释放。鉴于超氧化物的毒性明显高于过氧化物，以及生物介质和海水中氯化物的高含量，文中讨论了这些结果对银纳米颗粒毒理学的影响。
