Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3–20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

淡水通量和能耗是膜脱盐过程的两个重要基准。在这里，我们表明，纳米多孔碳复合膜（包括在多孔陶瓷基底上生长的一层多孔碳纤维结构）可以显示100％的淡化度和比现有的聚合物膜高3至20倍的淡水通量。热核算实验表明，碳复合膜可节省80％以上的潜热消耗。理论计算与分子动力学模拟相结合，揭示了膜中发生的独特微观过程。当盐溶液停在纳米级多孔通道的开口处并形成弯月面时，蒸汽可以迅速迁移穿过纳米级间隙以在渗透物侧冷凝。这个过程是由化学势梯度驱动的，并由碳表面的独特光滑度来辅助。碳复合膜的高导热率确保了大部分潜热被回收。