Water content modulation enables selective ion transport in 2D MXene membranes

• 成果类型: Article
• 署名作者: Zhu, Yaguang; Xiong, Qinsi; Jeon, Woo Cheol; Blum, Monika; Camino, Fernando; Schatz, George C.; Hatzell, Kelsey B.
• 署名单位: Princeton University; Northwestern University; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; United States Department of Energy (DOE); Lawrence Berkeley National Laboratory; United States Department of Energy (DOE); Brookhaven National Laboratory; Princeton University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11235
• DOI: 10.1073/pnas.2501017122
• 发表日期: 2025-07-22
• 关键词: 2-dimensional titanium carbide; total-energy calculations; mass-transport; lamellar membrane; intercalation; desalination; capacitance; EFFICIENCY

摘要

Separation membranes are critical for a range of processes, including but not limited to water desalination, chemical and fuel production, and recycling and recovery applications. Fundamentally, there are intrinsic trade-offs between permeability and selectivity. Local water organization and content can impact membrane structure and impact selective ion permeation. Intercalation of chaotropic cesium (Cs+) ions within the layers reduces the water content in the membrane and at the surface which cannot be found in the intercalation of other ions. Additionally, 3D imaging using focused ion beam scanning electron microscopy showed fewer defects in the Cs-MXene membrane, due to reduced local water content, leading to more efficient ion sieving. Xray diffraction and density functional theory calculations on the nanochannel structure demonstrated that the chaotropic ion results in the smallest nanochannel size and induces a stronger resistance to water-induced nanochannel swelling. With a narrower more selective transport of lithium over other metal cations, as evidenced in both experiment and molecular dynamics simulations. Our findings highlight the potential demand transport of ions for diverse applications.