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

Abstract

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.

In-situ reduction of graphene oxide for electrochemical supercapacitor application

“…The high pressure (＞1 GPa) inside the interlayer of GO [44,45] is assumed to play a vital role in countering the in-plane strain caused by reduction. This laminar confinement phenomenon potentially keeps the near original GO laminar-membrane and sheet morphology of VGM and VG-M, respectively.…”

2D–2D Nanoheterostructure of an Exposed {001}-Facet CuO and MoS2 Based Bifunctional Catalyst Showing Excellent Surface Chemistry and Conductivity for Cathodic CO2 Reduction

“…However, this limitation assumes that we have an equal portion of Cu and O terminated CuO nanosheets. Moreover, they have two exposed surface area, and we can preferentially synthesize nanosheets with Cu termination on both surfaces using proper control of the synthesis conditions and utilizing recent development in bottom-up electrochemical synthesis of atomically thin TMOs based non-vdW nanostructures …”

“…Moreover, they have two exposed surface area, and we can preferentially synthesize nanosheets with Cu termination on both surfaces using proper control of the synthesis conditions and utilizing recent development in bottom-up electrochemical synthesis of atomically thin TMOs based non-vdW nanostructures. 61 Although the NC: O system does not directly fulfill the required energy level positions for both half reactions of photocatalytic reduction of CO 2 , the spatially separated photogenerated carriers due to the intrinsic dipole 62 allocate extra electrons for the electrocatalysis CO 2 RR reactions. This kind of Schottky enhanced photocatalysis has been validated experimentally for the CoP/g-C 3 N 4 heterostructure, which is a similar metallic-semiconductor system.…”

Synthesis and protection: a controllable electrochemical approach to polypyrrole-coated copper azide with superior safety for MEMS

“…Electrochemical method is attractive for synthesis due to its simplicity, high yield, and mild conditions. 18–20 In our previous work, a series of electrochemical methods were developed for preparing CA materials. 21–25 This strategy circumvents the use of highly dangerous HN 3 gas and significantly shortens the azidation time.…”