We present a simple strategy for the fabrication of porous carbon nanofibers (see figure). This procedure produces thin webs by electrospinning a polymer solution containing different concentrations of zinc chloride and subsequently thermally treating the system. Their resulting surface area and good electrical conductivity make these porous carbon nanofibers useful in the fabrication of efficient electrodes for supercapacitors.

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Small-diameter carbon nanotubes (CNTs) are shown to enable exceptionally fast transport of water vapor under a concentration gradient driving force. Thanks to this property, membranes having sub-5 nm CNTs as conductive pores feature outstanding breathability while maintaining a high degree of protection from biothreats by size exclusion.

Engineered osmosis (e.g., forward osmosis, pressure-retarded osmosis, direct osmosis) has emerged as a new platform for applications to water production, sustainable energy, and resource recovery. The lack of an adequately designed membrane has been the major challenge that hinders engineered osmosis (EO) development. In this study, nanotechnology has been integrated with membrane science to build a next generation membrane for engineered osmosis. Specifically, hydrophilic nanofiber, fabricated from different blends of polyacrylonitrile and cellulose acetate via electrospinning, was found to be an effective support for EO thin film composite membranes due to its intrinsically wetted open pore structure with superior interconnectivity. The resulting composite membrane exhibits excellent permselectivity while also showing a reduced resistance to mass transfer that commonly impacts EO processes due to its thin, highly porous nanofiber support layer. Our best membrane exhibited a two to three times enhanced water flux and 90% reduction in salt passage when compared to a standard commercial FO membrane. Furthermore, our membrane exhibited one of the lowest structural parameters reported in the open literature. These results indicate that hydrophilic nanofiber supported thin film composite membranes have the potential to be a next generation membrane for engineered osmosis.

This work demonstrates a more accurate method for calculating structural parameter (S) of asymmetric osmotic membranes using experimental data and a theoretical flux model which encapsulates all significant boundary layer phenomena. External boundary layer effects on the porous side of the membrane have been neglected in many current models. In these models, external concentration polarization (ECP) effects get combined with the internal concentration polarization (ICP), resulting in inflated S values. In this study, we proposed a new flux model in which ECP effects are accounted for so that S can be more accurately measured. This model considered the in-series resistances for solute transport based on intrinsic properties of the membrane as well as boundary layers at membrane surfaces and within the support layer. The results indicate that ICP is less severe than previously predicted and that cross-flow velocity, temperature and concentration of the draw and the feed solutions impact both external and internal concentration polarization. Our calculations also surprisingly show that changes in cross-flow velocity impact internal concentration polarization due to induced mixing within the support layer. Also, we suggest that it is critical to consider the "residence time" of solutes in the vicinity of the selective layer in determining the membrane selectivity.