Hydrophobic-Modified, Stable MXene Membrane Joule Heater for Water Purification

MXenes, two-dimensional transition metal carbides and nitrides, exhibit outstanding metallic conductivity and electrothermal responsiveness as promising candidates for electrothermal energy conversion. However, their practical application in aqueous or corrosive environments has been limited due to rapid oxidation and hydrophilic surface termination, which degrade electrical stability and long-term functionality. This study proposes a hydrophobic modification strategy for Ti3C2Tx MXene via oleylamine (OAm) ligand exchange, which enhances oxidation resistance and hydrophobicity by introducing an interfacial barrier, as reflected by electrochemical impedance measurements, while maintaining sufficient electrical conductivity for stable electrothermal operation. The surface-engineered MXene exhibits stable and uniform Joule heating characteristics during DC operation in aqueous media and maintains a consistent temperature rise and minimal electrochemical degradation compared to pristine MXene. Structural and surface analysis confirmed that OAm passivation reduces ion accessibility and preserves MXene’s interfacial structure. In a practical demonstration, the modified MXene film was applied as an additional surface barrier on pristine MXene heaters for water evaporation and purification, resulting in sustained high performance and efficiency compared with devices based solely on pristine MXene films. This study highlights that hydrophobic surface engineering of MXene enables a robust and scalable electrothermal platform as a stabilized conductive nanomaterial.