Zhang Fei, Yu Zhou, Rondinone Adam J, Huang Jingsong, Sumpter Bobby G, Qiao Rui
Department of Mechanical Engineering , Virginia Tech , Blacksburg , Virginia 24061 , United States.
Langmuir. 2018 Dec 4;34(48):14552-14561. doi: 10.1021/acs.langmuir.8b03161. Epub 2018 Nov 26.
The adsorption of gas molecules at electrode-electrolyte interfaces is an important step in electrochemical reactions. Using molecular dynamics simulations, we investigate the adsorption of dissolved N in the electrical double layers (EDLs) of an aqueous electrolyte near planar and 1 nm radius spherical carbon electrodes. The adsorption of N is found to be overall enriched near neutral electrodes regardless of their surface curvature, although it can be locally enriched or depleted depending on the distance from the electrode surface. In comparison, the adsorption of N in the EDL near negatively charged electrodes is found to increase under a moderate surface charge density, but decrease under a high surface charge density, especially near a planar electrode. By analyzing the potential of mean force for dissolved N, the solvent-induced effects are found to play important roles in influencing the adsorption of N in the EDLs. The adsorption behavior of N molecules, especially their dependence on the surface charge and curvature of electrodes, is further rationalized by examining the structure of interfacial water molecules, their interference with the hydration shell of N, and their modification by the electrification of electrodes.
气体分子在电极 - 电解质界面的吸附是电化学反应中的重要步骤。利用分子动力学模拟，我们研究了溶解态氮在平面和半径为1 nm的球形碳电极附近水性电解质双电层（EDLs）中的吸附情况。结果发现，无论电极表面曲率如何，氮的吸附在中性电极附近总体上是富集的，不过根据与电极表面的距离，其吸附情况可能在局部出现富集或贫化。相比之下，发现在中等表面电荷密度下，带负电电极附近EDL中氮的吸附会增加，但在高表面电荷密度下会减少，尤其是在平面电极附近。通过分析溶解态氮的平均力势，发现溶剂诱导效应在影响EDL中氮的吸附方面起着重要作用。通过研究界面水分子的结构、它们对氮水合壳层的干扰以及电极带电对它们的改性，进一步解释了氮分子的吸附行为，特别是它们对电极表面电荷和曲率的依赖性。
