Graphene-based laminar membranes open new avenues for water treatment; in particular, reduced graphene oxide (rGO) membranes with high stability in aqueous solutions are gaining increased attention for desalination. However, the low water permeability of these membranes significantly limits their applications. In this study, the water permeability of thermally reduced GO membrane was increased by a factor of 26 times by creating in-plane nanopores with an average diameter of ∼3 nm and a high density of 2.89 × 10 15 m −2 via H 2 O 2 oxidation. These in-plane nanopores provide additional transport channels and shorten the transport distance for water molecules. Meanwhile, salt rejection of this membrane is dominated by both the Donnan effect and the size exclusion of the interspaces. Besides, the water permeability and salt rejection of the thermally reduced nanoporous GO membrane can also be simply tuned by adjusting the thermal treatment time and membrane thickness. Additionally, the fabricated membrane exhibited a relatively stable rejection of Na 2 SO 4 during the long-term testing. This work demonstrates a novel and effective strategy for fabricating high-performance laminar rGO membranes for desalination applications.

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In most of the reported n-n heterojunction photocatalysts, both the conduction and valence bands of one semiconductor are more negative than those of the other semiconductor. In this work, we designed and synthesized a novel n-n heterojunction photocatalyst, namely CdS-ZnWO4 heterojunctions, in which ZnWO4 has more negative conduction band and more positive valence band than those of CdS. The hydrogen evolution rate of CdS-30 mol %-ZnWO4 reaches 31.46 mmol h(-1)  g(-1) under visible light, which is approximately 8 and 755 times higher than that of pure CdS and ZnWO4 under similar conditions, respectively. The location of the surface active sites is researched and a plausible mechanism of performance enhancement by the tuning of the structure is proposed based on the photoelectrochemical characterization. The results illustrate that this kind of nonconventional n-n heterojunctions is also suitable and highly efficient for solar hydrogen evolution.

Reduced graphene oxide membranes (rGOMs) have been intensively studied for desalination and molecular sieving applications, benefiting from their selective and stable two-dimensional (2D) nanochannels. However, their performance is usually over-rated because of the limited understanding of nanowrinkles. In this study, we tuned 2D nanochannels and nanowrinkles in rGOMs to improve their performance and revealed the underlying role of nanowrinkles for water and salt separation. A good trade-off between water permeance (1.05 LMH/bar) and NaCl rejection (83%) was obtained in rGOMs thermally treated in air (Air-rGO), compared with their counterparts synthesized via thermal treatment in vacuum (Va-rGO) and HI vapor reduction (HI-rGO). Instead of the narrow and impermeable 2D nanochannels in Va-rGO and HI-rGO, 5–10 nm-sized nanowrinkles were evident to transport water and salts without selectivity, leading to the low water permeance and NaCl rejection. For Air-rGO membranes, however, the smaller and fewer nanowrinkles retarded the NaCl transfer and the slightly narrowed 2D nanochannels maintained the fast water flow, contributing to the high NaCl rejection and water permeance, respectively. This study provides new insights into the mass transport mechanism in nanowrinkles of rGOMs and advances the design of 2D membranes for desalination, molecular/ionic sieving, and other environmental applications.

TFC membranes are fabricated via an interfacial polymerization (IP) process involving two monomers: an amine such as m-phenylenediamine (MPD), piperazine (PIP) and phenylenediamine (PPD) dissolved in an aqueous solution; and a polyfunctional acid chloride such as trimesoyl chloride (TMC) dissolved in an organic solvent. [11] As shown in Figure 1a, a common configuration of TFC membranes includes: 1) a top ultrathin skin polyamide (PA) layer (200 nm) which controls the separation performance; 2) a middle porous support layer (60 µm) which provides the necessary mechanical support and functions as a platform for IP process; and 3) a bottom nonwoven fabric layer (100 µm) which gives further mechanical support. [12] With the advantages of this structure, TFC membranes can achieve efficient separation while maintaining mechanical strength.Despite its wide applications, TFC membranes are still facing many challenges, particularly, the trade-off between the water permeability and the solute rejection in PA films. [13] The latest review in 2019 presented a more accurate upper bound of polymer TFC membranes through analyzing more than 300 TFC-related studies, as shown in Figure 1b. [14] Based on the solution-diffusion mechanism of the TFC membranes, an increase of water permeance would inevitably lead to a decrease of solute rejection. There is an ultimate limit for the development of traditional polymer TFC membranes. Moreover, membrane fouling and chlorination pose constant challenges in the application of polymer TFC membranes. However, the demand for freshwater in human society seems bottomless, and thus high-performance TFC membranes are required.Integrating nanomaterials into the polymer TFC membranes to form TFN membranes has been identified as a promising technique to solve the drawbacks of TFC membranes. In 2007, Hoek and co-workers [15] originally developed a thinfilm nanocomposite (TFN) membrane by adding NaA zeolite into the PA matrix. Afterward, various advanced nanomaterials, carbon nanotubes, [16,17] zeolite, [15][16][17][18][19] inorganic nanoparticles, [20,21] zeolitic imidazolate framework, [22,23] metal-organic framework, [24] and so on have been incorporated with TFC membranes. Particularly, the 2D forms of these nanomaterials are believed to be excellent candidates for fabricating high-performance TFN membranes. This work is to make an exhaustive examination of current research on 2D materials Membrane-based separation technologies are essential in the fields of desalination and wastewater treatment. 2D material based thin-film nanocomposite (2D-M-TFN) membranes are emerging technology that combines 2D nanomaterials and conventional thin-film composite membranes. It has great potential to further improve the efficiency of the membrane separation process. Although extensive studies are reported, 2D-M-TFN membranes for water treatment are not systemically reviewed. This work gives an intensive summary of this emerging technology. The function, mechanisms, and common characteristics of various 2D materia...