Liu Tianqi, Liang Wenbin, Li Hong, Lv Zixiao, Liang Xiaoye, Hao Jianguo, Ding Youqian, Wu Wangsuo, Chen Ximeng, Li Zhan
Interfacial forces and nanoconfined environments play crucial roles in transport phenomena within low-dimensional materials. In this study, we propose a photothermally regulated surface-tension mechanism for hydrogen-isotope fractionation, in which light-induced changes in the surface tension of gallium ( Ga ) dynamically modulate the confined environment between graphene oxide ( GO ) layers. Under near-infrared irradiation, the surface tension of Ga decreases, altering its wettability within the interlayer galleries and inducing a reversible contraction of the GO interlayer spacing. temperature-dependent transmission electron microscopy confirmed this dynamic modulation, showing that confined Ga nanoparticles undergo fully reversible expansion-contraction and display surface-energy-driven extension behavior analogous to macroscopic particles. Such confinement-induced structural responsiveness regulates the local arrangement of water molecules, leading to distinct molecular aggregation states for H 2 O and D 2 O . Due to stronger intermolecular attraction, D 2 O diffusion is more restricted in confinement, leading to pronounced isotope selectivity. Experimentally, the membrane achieved a separation factor of 70.53 for H 2 O : D 2 O and demonstrated selective removal of tritium water ( T 2 O ). Our study elucidates the interplay between photothermally driven interfacial energy modulation and confined molecular transport, offering new insights into tunable separation processes and interfacial physics.