Janus Interface Materials: Reshaping Liquid-to-Vapor Mass Transfer through Asymmetry
Liquid-to-vapor mass transfer is central to energy and environmental processes. Conventional distillation relies on vapor-liquid equilibrium and device-level optimization, with materials playing passive structural roles. Non-boiling processes such as membrane distillation and interfacial solar evaporation localize phase change at confined interfaces, making mass transfer a materials-mediated transport phenomenon where interfacial structure and chemistry dictate evaporation kinetics, vapor escape, and solute rejection. Janus interface materials, featuring spatially separated hydrophilic and hydrophobic domains, introduce architectural asymmetry to regulate liquid-to-vapor mass transfer. This review summarizes recent advances, highlighting mechanisms including the cooperative pump-valve effect, nanoconfinement-enhanced transport, and mitigation of fouling and scaling. Representative applications in membrane distillation, solar-driven evaporation, and personal thermal-moisture management are systematically discussed. Key challenges and future opportunities are outlined, particularly in advancing fundamental understanding, scalable fabrication, and practical implementation.