Tunable mass transport in the artificial smart membranes based on two-dimensional materials

Inspired by biological systems in nature, smart membranes with stimuli responsiveness exhibit advantages over traditional membranes with stationary structures and have shown the potential in breaking the thresholds of traditional membrane technologies. Unfortunately, responsive polymeric membranes suffer from inevitable fouling and the trade-off effect between permeability and selectivity, seriously hindering further applications. Recently, smart membranes based on two-dimensional (2D) nanomaterials with regulated nanochannel sizes and surface charges triggered by external stimuli have attracted increasing attention and are highly suitable for membrane technologies due to their promising properties. In this review, we summarize the state-of-art progress on the 2D smart membranes (2DSMs) including the general design strategies for fabricating 2DSMs, recent advances in responsive mechanisms under various stimuli and diverse applications such as gas separation, water treatment, ion rectification and osmotic energy harvest. To conclude, we propose a brief perspective on the challenges and opportunities in this fast-growing field.