Forward osmosis (FO), as an emerging technology for seawater desalination and wastewater reuse, has been attracting significant interest because of its energy efficiency. However, membrane fouling represents one of the major limitations for this technology, notably for thin film composite (TFC) polyamide (PA) membranes, which are prone to chlorine attack. In this study, silver nanoparticle (AgNPs)-decorated graphene oxide (GO) nanosheets (as an effective biocidal material) were covalently bonded to the PA surface to impart improved hydrophilicity and antibacterial properties to the membrane. AgNPs were synthesized in situ by the wet chemical reduction of silver nitrate onto the surface of GO nanosheets. The formation of the composite was verified by UV-vis spectroscopy, X-ray diffraction, and transmission electron microscopy techniques. The synthesized GO/Ag nanocomposites were then covalently bonded onto the TFC PA membrane surface using cysteamine through an amide forming condensation reaction.ATR-FTIR and XPS results confirmed the covalent bonding of the nanocomposite onto the TFC PA surface. Overall, the GO/Ag nanocomposite functionalized membranes exhibited super-hydrophilic properties (contact angles below 25°) and significant bacterial (E. coli) inactivation (over 95% in static bacterial inactivation tests) without adversely affecting the membrane transport properties. † Electronic supplementary information (ESI) available: FE-SEM and backscatter electron microscopy of (A) GO functionalized TFC and (B) GO/Ag nanocomposite functionalized TFC. Elements with high atomic numbers backscatter electrons more strongly than lighter elements with low atomic numbers and thus appear brighter on the image (Fig. S1). TEM images of (A) GO, (B) Ag NPs, and (C) GO/ Ag nanocomposite (Fig. S2). ATR-FTIR spectra of (A) a GO nanosheet and GO/Ag nanocomposite and (B) a control TFC and GO/Ag nanocomposite functionalized TFC membrane (Fig. S3). The zeta potential of the surface of the pristine and functionalized membranes as a function of solution pH. Measurements were taken at room temperature (23°C) in a solution of 1 mM KCl by adjusting pH with the dropwise addition of HCl and NaOH (Fig. S4). Surface roughness properties of pristine and GO/Ag functionalized TFC FO membranes (Table S1). XPS results for (A) pristine membrane and (B) cysteamine treated TFC FO membranes. Peaks at 198 eV for Cl2P and 162 for sulfur S2P are shown in (A) and (B), respectively (Fig. S5). Elemental composition of the membrane surface of pristine and functionalized membranes before and after sonication (Table S2). The physical stability of the silver NPs on the Ag NP decorated and GO/Ag functionalized membranes from XPS results. A 7 min bath sonication was applied to the membranes, and the percent of silver on the membrane surface was estimated (Fig. S6). SeeTo address the biofouling problem associated with thin film composite (TFC) forward osmosis (FO) membranes, we have developed novel surface coatings through covalent bonding of silver decorated grap...