Graphene oxide membranes with high permeability and selectivity for dehumidification of air Yongsoon Shin, 1 Wei Liu, 2 Birgit Schwenzer, 1 Sandeep Manandhar, 3,4 Dylan Chase- Woods, 2,5 Mark H. Engelhard, 3 Ram Devanathan, 2 Leonard S. Fifield, 2 Wendy D. Bennett, 2 Bojana Ginovska 1 David W. Gotthold 2* 1 Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA 2 Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA 3 W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA 4 Department of Materials Science & Engineering, University of Washington, Seattle, WA 98195 5 Department of Physics, University of Washington, Seattle, WA 98195 Abstract Hierarchically stacked 2D graphene oxide (GO) membranes are a fascinating and promising new class of materials with the potential for radically improved water vapor/gas separation with excellent selectivity and high permeability. This paper details dehumidification results from flowing gas mixtures through free-standing GO membrane samples prepared by a casting method. The first demonstrated use of free-standing GO membranes for water vapor separation reveals outstanding water vapor permeability and H 2 O/N 2 selectivity. Free-standing GO membranes exhibit extremely high water vapor permeability of 1.82 x 10 5 Barrer and a water vapor permeance of 1.01 x 10 -5 mol/m 2 sPa, while the nitrogen permeability was below the system’s detection limit, yielding a selectivity >10 4 in 80% relative humidity (RH) air at 30.8 °C. The results show great potential for a range of energy conversion and environmental applications. * Corresponding author. Tel.: +1-509-375-2073; E-mail: david.gotthold@pnnl.gov (D. W. Gotthold).