Kaust Catalysis Center (KCC), Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Department of Chemical and Biomolecular Engineering, Faculty of Engineering, National University of Singapore, Singapore 119260, Singapore.
Int J Mol Sci. 2022 Oct 7;23(19):11926. doi: 10.3390/ijms231911926.
Transition metal dichalcogenides (TMDCs) can be used as optical energy conversion materials to catalyze the water splitting reaction. A good catalytical performance requires: (i) well-matched semiconductor bandgaps and water redox potential for fluent energy transfer; and (ii) optimal orientation of the water molecules at the interface for kinetically fast chemical reactions. Interactions at the solid-liquid interface can have an important impact on these two factors; most theoretical studies have employed semiconductor-in-vacuum models. In this work, we explored the interface formed by liquid water and different types of TMDCs monolayers (MoS, WSe, and their lateral heterojunctions), using a combined molecular dynamics (MD) and density functional theory (DFT) approach. The strong interactions between water and these semiconductors confined the adsorbed water layer presenting structural patterns, with the water molecules well connected to the bulk water through the hydrogen bonding network. Structural fluctuations in the metal chalcogenide bonds during the MD simulations resulted in a 0.2 eV reduction of the band gap of the TMDCs. The results suggest that when designing new TMDC semiconductors, both the surface hydrophobicity and the variation of the bandgaps originating from the water-semiconductor interface, need to be considered.
过渡金属二硫属化物（TMDCs）可用作光学能量转换材料，以催化水分解反应。良好的催化性能需要：（i）匹配良好的半导体带隙和水氧化还原电位，以实现流畅的能量转移；（ii）在界面处水分子的最佳取向，以实现动力学快速化学反应。固液界面的相互作用对这两个因素有重要影响；大多数理论研究都采用了半导体真空模型。在这项工作中，我们使用分子动力学（MD）和密度泛函理论（DFT）相结合的方法，研究了不同类型的 TMDCs 单层（MoS、WSe 及其横向异质结）与液态水形成的界面。水与这些半导体之间的强相互作用限制了吸附水层呈现出结构模式，水分子通过氢键网络与体相水紧密相连。在 MD 模拟过程中金属硫属键的结构波动导致 TMDCs 的带隙减小了 0.2eV。结果表明，在设计新型 TMDC 半导体时，需要考虑表面疏水性以及源自水半导体界面的带隙变化。
