ABSTRACT
The scarcity of fresh water resources has become increasingly serious in recent years, posing threats to the survival of mankind. The ability of the animals and plants in arid areas to collect water from moisture and fog has drawn attention worldwide. Inspired by the synergistic fog harvesting mode of natural organisms with superhydrophilic and superhydrophobic patterning, a composite membrane with a concave-convex morphology and hybrid wettability was prepared aiming at efficient fog harvesting. The hybrid wettability surface was obtained by chemically modifying the superhydrophilic PAN substrate with 1H,1H,2H,2H-perfluorooctyltrichlorosilane using iron mesh as the mask. The porous PAN substrate was prepared by the non-solvent-induced phase separation (NIPS) method. Fog harvesting is a three-step process: condensation, coalescence, and rapid transportation of water droplets. The area and ratio of the hydrophilic/hydrophobic regions were tuned by adjusting the mesh number of the iron meshes. Under the optimal condition, the fog harvesting efficiencies of 40.3 and 74.2 mg·cm-2·min-1 were obtained when the fog yields were 0.05 and 0.1 L·min-1, respectively. The present work provides an alternative strategy for addressing the shortage of fresh water resources.
ABSTRACT
We report an enhanced light-harvesting two-dimensional nanofluidic system based on a homogeneous graphene derivative nanocomposite membrane, and demonstrate an enhanced proton flow upon asymmetric light illumination. The maximum photocurrent is achieved by appropriately sandwiching graphene oxide quantum dots for adjusting the interlayer spacing of the membrane and reinforcing the membrane potential.
ABSTRACT
Cation-π interactions are common in nature, especially in organisms. Their profound influences in chemistry, physics, and biology have been continuously investigated since they were discovered in 1981. However, the importance of cation-π interactions in materials science, regarding carbonaceous nanomaterials, has just been realized. The interplay between cations and delocalized polarizable π electrons of graphene would bring about significant changes to the intrinsic characteristics of graphene and greatly affect the device performance based on graphene and its derivatives. Here, the cation-π interactions in graphene containing systems for water treatment applications (e.g., separation membranes, adsorbents) are highlighted. The cross-linking effects caused by cation-π interactions contribute to membrane stability and selectivity and enhanced adsorption. Their roles in dominating the performance of graphene-based structures for other specific applications are also discussed. Relevant theoretical modeling and calculations are summarized to offer an in-depth understanding of the underlying mechanisms which can help in designing more functional materials and structures. Perspectives on the potential directions that deserve effort are also presented.
ABSTRACT
Hybrid coagulant/flocculant consisting of nanomaterials have tremendous potential in solid-liquid separation and can be applied to the coagulation-flocculation-sedimentation process of water treatment. In this work, inspired by the mineralization in nature, a graphene oxide/polymer-based hybrid coagulant/flocculant that precipitates large-scale, multicomponent (e.g., dyes, heavy metal ions, and nanoparticles) and complex pollutants simultaneously at room temperature by forming double-network hydrogel through bioinspired Ca2+ crosslinking, is developed for the purification of wastewater. The coagulation-flocculation-sedimentation method developed here also provides a novel strategy for the preparation of macroscopic assemblies of multicomponents that can be applied to various application fields.
ABSTRACT
Graphene oxide (GO) has been demonstrated as the most promising candidate for surface modification of polymer separation membranes for durable filtration applications. However, the adhesion between GO coating and polymer substrate, as the most essential issue for reliable applications, has been little explored. Herein, we developed a facile high-pressure assisted deposition method to physically anchor GO sheets on microfiltration (MF) and reverse osmosis (RO) membranes, and established a tape test procedure for assessing the adhesion of GO coating to polymer substrates based on the ASTM D3359. Through regulating the GO sources and coating process, we demonstrated that the adhesion depends sensitively on the GO flake size and deposition pressure, whereas the adhesion level dramatically improved from 0B to 5B, with decrease in the lateral size of GO and increase in the coating deposition pressure. The strong GO coatings showed evidently higher water flux than that of weak counterparts. The underlying mechanism was further analyzed and verified. Nanosize of GO and high deposition pressure favor the formation of the conformal morphologies of GO coatings on both MF and RO membranes, which allow strong interfacial van der Waals interaction because of the large contact areas and result in the strong GO coatings on membranes. These results potentially open up a versatile pathway to develop the strong graphene-based coatings on separation membranes.
ABSTRACT
Correction for 'The physics and chemistry of graphene-on-surfaces' by Guoke Zhao, Xinming Li, Meirong Huang et al., Chem. Soc. Rev., 2017, 46, 4417-4449.
ABSTRACT
Graphene has demonstrated great potential in next-generation electronics due to its unique two-dimensional structure and properties including a zero-gap band structure, high electron mobility, and high electrical and thermal conductivity. The integration of atom-thick graphene into a device always involves its interaction with a supporting substrate by van der Waals forces and other intermolecular forces or even covalent bonding, and this is critical to its real applications. Graphene films on different surfaces are expected to exhibit significant differences in their properties, which lead to changes in their morphology, electronic structure, surface chemistry/physics, and surface/interface states. Therefore, a thorough understanding of the surface/interface properties is of great importance. In this review, we describe the major "graphene-on-surface" structures and examine the roles of their properties and related phenomena in governing the overall performance for specific applications including optoelectronics, surface catalysis, anti-friction and superlubricity, and coatings and composites. Finally, perspectives on the opportunities and challenges of graphene-on-surface systems are discussed.
