Xu Lihua, Jiang De-En
Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA.
J Chem Phys. 2021 Dec 21;155(23):234707. doi: 10.1063/5.0066835.
Heterostructures of 2D materials offer a fertile ground to study ion transport and charge storage. Here, we use ab initio molecular dynamics to examine the proton-transfer/diffusion and redox behavior in a water layer confined in the graphene-TiCO heterostructure. We find that in comparison with the similar interface of water confined between TiCO layers, the proton redox rate in the dissimilar interface of graphene-TiCO is much higher, owing to the very different interfacial structure as well as the interfacial electric field induced by an electron transfer in the latter. Water molecules in the dissimilar interface of the graphene-TiCO heterostructure form a denser hydrogen-bond network with a preferred orientation of water molecules, leading to an increase in proton mobility with proton concentration in the graphene-TiCO interface. As the proton concentration further increases, proton mobility decreases due to increasingly more frequent surface redox events that slow down proton mobility due to binding with surface O atoms. Our work provides important insights into how the dissimilar interface and their associated interfacial structure and properties impact proton transfer and redox in the confined space.
二维材料的异质结构为研究离子传输和电荷存储提供了丰富的研究领域。在此，我们使用从头算分子动力学方法来研究限制在石墨烯 - 二氧化钛（TiCO）异质结构中的水层中的质子转移/扩散和氧化还原行为。我们发现，与限制在TiCO层之间的水的类似界面相比，石墨烯 - TiCO不同界面中的质子氧化还原速率要高得多，这是由于后者界面结构差异很大以及电子转移诱导的界面电场所致。石墨烯 - TiCO异质结构不同界面中的水分子形成了更密集的氢键网络，且水分子具有优先取向，导致石墨烯 - TiCO界面中质子迁移率随质子浓度增加而增大。随着质子浓度进一步增加，质子迁移率降低，这是因为表面氧化还原事件越来越频繁，质子与表面O原子结合，减缓了质子迁移率。我们的工作为不同界面及其相关的界面结构和性质如何影响受限空间中的质子转移和氧化还原提供了重要见解。
