Angstrom-confined solvents in 2D laminates can travel through interlayer spacings, through gaps between adjacent sheets, and via in-plane pores. Among these, experimental access to investigate the mass transport through in-plane pores is lacking. Our experiments allow an understanding of this mass transport via the controlled variation of oxygen functionalities, size and density of in-plane pores in graphene oxide membranes. Contrary to expectations, our transport experiments show that higher in-plane pore densities may not necessarily lead to higher water permeability. We observed that membranes with a high in-plane pore density but a low amount of oxygen functionalities exhibit a complete blockage of water. However, when water− ethanol mixtures with a weaker hydrogen network are used, these membranes show an enhanced permeation. Our combined experimental and computational results suggest that the transport mechanism is governed by the attraction of the solvents toward the pores with functional groups and hindered by the strong hydrogen network of water formed under angstrom confinement.

Due to the excellent chemical inertness, graphene can be used as an anti-corrosive coating to protect metal surfaces. Here, we report the growth of graphene by using a chemical vapour deposition (CVD) process with ethanol as a carbon source. Surface and structural characterisations of CVD grown films suggest the formation of double-layer graphene. Electrochemical impedance spectroscopy has been used to study the anticorrosion behaviour of the CVD grown graphene layer. The observed corrosion rate of 8.08 × 10−14 m/s for graphene-coated copper is 24 times lower than the value for pure copper which shows the potential of graphene as the anticorrosive layer. Furthermore, we observed no significant changes in anticorrosive behaviour of the graphene coated copper samples stored in ambient environment for more than one year.

Bottom‐up electrochemical synthesis of atomically thin materials is desirable yet challenging, especially for non‐van der Waals (non‐vdW) materials. Thicknesses below a few nanometers have not been reported yet, posing the question how thin can non‐vdW materials be electrochemically synthesized. This is important as materials with (sub‐)unit‐cell thickness often show remarkably different properties compared to their bulk form or thin films of several nanometers thickness. Here, a straightforward electrochemical method utilizing the angstrom‐confinement of laminar reduced graphene oxide (rGO) nanochannels is introduced to obtain a centimeter‐scale network of atomically thin (<4.3 Å) 2D‐transition metal oxides (2D‐TMO). The angstrom‐confinement provides a thickness limitation, forcing sub‐unit‐cell growth of 2D‐TMO with oxygen and metal vacancies. It is showcased that Cr2O3, a material without significant catalytic activity for the oxygen evolution reaction (OER) in bulk form, can be activated as a high‐performing catalyst if synthesized in the 2D sub‐unit‐cell form. This method displays the high activity of sub‐unit‐cell form while retaining the stability of bulk form, promising to yield unexplored fundamental science and applications. It is shown that while retaining the advantages of bottom‐up electrochemical synthesis, like simplicity, high yield, and mild conditions, the thickness of TMO can be limited to sub‐unit‐cell dimensions.

Abstract2-Dimensional materials-based membranes have been considered as promising candidates for water purification. Here, we report that graphene oxide (GO) membrane can reject aquatic humic acid (HA) up to 94.2% in a 2-bar pressurized filtration process. In-depth analysis indicated that the filtration performances such as water flux and rejection rate depend on the thickness and physical structure of the membranes. The experimental study reveals that the GO membrane with a mass loading of 0.58 mg/cm2, which is approximately equivalent to 3 μm thickness, is required to reach the rejection rate of HA at 94% using 2 bar pressurized filtration method. We further confirmed the membranes’ integrity by over 98% rejection of methylene blue (MB). For practicality, we tested our membrane in tubular form by coating GO on PVDF hollow fibres, which presented similar rejection performances using vacuum filtration method while maintaining the water flux around 100 L m−2 h−1 bar−1. Graphical abstract

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Materials in 2-dimensional (2D) form often show remarkable properties and unexplored scientific phenomena compared to their bulk form. Layered, van der Waals (vdW) materials have an obvious 2D structure, whereas non-vdW materials have no preference to obtain 2D form. This severely limits the number of currently available 2D non-vDW materials. Here, we introduce a straightforward electrochemical method utilizing the angstrom-confinement of laminar reduced graphene oxide (rGO) nanochannels to obtain 2D transition metal oxides (2D-TMO), a class of non-vdW materials. During synthesis the angstrom-confinement provides a thickness limitation, forcing a sub-unit cell growth of 2D-TMO with oxygen and metal vacancies. The resulting flexible sandwich structure of rGO sheets inserted by a porous polycrystalline network of 2D-TMO is created in centimetre scale. Our accessible method for obtaining 2D-TMO holds high promise to yield exciting properties for fundamental science and applications.

Bottom-up electrochemical synthesis of atomically thin materials is desirable yet challenging, especially for non-van der Waals (vdW) materials. Thicknesses below few nm have not been reported yet, posing the question how thin can non-vdW materials be electrochemically synthesized? This is important as materials with (sub-) unit cell thickness often show remarkably different properties compared to their bulk form or thin films of several nm thickness. Here, we introduce a straightforward electrochemical method utilizing the angstrom-confinement of laminar reduced graphene oxide (rGO) nanochannels to obtain a centimeter-scale network of atomically thin (< 0.43nm) 2D-transition metal oxides (2D-TMO). The angstrom-confinement provides a thickness limitation, forcing sub-unit cell growth of 2D-TMO with oxygen and metal vacancies. We showcase that Cr2O3, a material without significant catalytic activity for OER in bulk form, can be activated as a high-performing catalyst if synthesized in the 2D sub-unit cell form. Our method displays the high activity of sub-unit cell form while retaining the stability of bulk form, promising to yield unexplored fundamental science and applications. We show that while retaining the advantages of bottom-up electrochemical synthesis like simplicity, high yield, and mild conditions, the thickness of TMO can be limited to sub-unit cell dimensions.

Materials in 2-dimensional (2D) form show remarkable properties and unexplored scientific phenomena compared to their bulk form. Layered, van der Waals (vdW) materials have an obvious 2D structure, whereas non-vdW materials have no preference to obtain 2D form. This limits the number of currently available 2D non-vDW materials. Here, we introduce a straightforward electrochemical method utilizing the angstrom-confinement of laminar reduced graphene oxide (rGO) nanochannels to obtain a porous polycrystalline network of 2D transition metal oxides (2D-TMO), a class of non-vdW materials. During synthesis the angstrom-confinement provides a thickness limitation, forcing sub-unit cell growth of 2D-TMO with oxygen and metal vacancies. We showcase that Cr2O3, a material without significant catalytic activity for OER in bulk form, can be activated as a high-performing catalyst if synthesized in the 2D sub-unit cell form. Our approach creates a strategy for combining the high activity of 2D form and high stability and robustness of bulk form. Our accessible method for obtaining 2D-TMO holds high promise to yield exciting properties for fundamental science and applications.