Electronic and magnetic properties of sub-unit cell α-Fe2O3 films on the α-Al2O3 (0001) substrate

et al. 2023

Preprint

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.

Section: Discussionmentioning

confidence: 99%

Angstrom-confined electrochemical synthesis of non van der Waals 2D metal oxides

et al. 2023

Preprint

“…49-53 54-56 Moreover, these 2D metal oxides may carry a range of exciting new scientific phenomena such as two dimensional ferromagnetic configurations. 33,57 In the future, precise control of synthesis parameters such as interlayer space of the rGO may allow to tailor properties of the resulting 2D TMO such as crystal orientation and metal/oxide vacancies.…”

Section: Discussionmentioning

confidence: 99%

Angstrom-confined electrochemical synthesis of non van der Waals 2D metal oxides

et al. 2022

Preprint

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.

“…Moreover, these 2D metal oxides may carry a range of exciting new scientific phenomena, such as 2D ferromagnetic configurations. [43,74] In the future, precise control of synthesis parameters such as interlayer space of the rGO may allow to tailor properties of the resulting 2D TMO, such as crystal orientation and metal/oxide vacancies.…”

Section: Conclusion and Perspectivementioning

confidence: 99%

Angstrom‐Confined Electrochemical Synthesis of Sub‐Unit‐Cell Non‐Van Der Waals 2D Metal Oxides

et al. 2023

Advanced Materials

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.