Following the graphene isolation, strong interest in two dimensional (2D) materials has been driven by their outstanding properties. Their typical intrinsic structure, including strong in-plane covalent bonding and weak out-of-plane Van der Waals interaction, makes them highly promising in diverse areas such as electronics, catalysis, and environment. Growth of 2D materials requires a synthesis approach able to control the deposition onto a support at the atomic scale. Thanks to their simplicity, versatility and ability to control thickness at the angstrom level, Atomic Layer Deposition (ALD) and its variant Atomic Layer Etching (ALET) appear as ones of the most suited techniques to synthesize 2D materials. The development of ALD technique for fabricating 2D materials in the last ten years justifies reviewing its most recent groundbreaking discoveries and progresses. Particular attention will be paid to stable 2D materials especially graphene, h-BN, Mo and W dichalcogenides and few monolayered metal oxides. Specificities and outputs of ALD for 2D material as well as emerging directions and remaining technical challenges will be highlighted. layers. This kind of materials exhibits interesting properties related to their size restriction: electronic confinement, modifying both optical and electronic properties, and high surface to volume ratio that affects the mechanical and chemical properties. 4,5 Therefore, 2D materials are highly attractive due to their potential in cutting edge domains such as micro-, and opto-electronics 4,6 as well as renewable energy, 4,7-9 catalysis, 10,11 gas sensing 12,13 and environment. 4,7,14,15 They are also exciting because of their possibility to be stacked into VdW heterostructures combining and/or tuning their chemical and physical properties. 6,[16][17][18] However, since 2D materials are atomically thin, a suitable manufacturing process capable of controlling their fabrication in terms of structure, composition, thickness, defects, purity and crystallinity without degradation of their original properties is necessary. Two approaches can be considered: the top-down and bottom-up synthetic routes. 19 Historically, top-down approach has first been developed using mechanical and chemical exfoliation techniques, 1,2,20,21 the first example being the well-known graphene exfoliation using scotch tape.Later on, etching processes have been adapted. Recently, Atomic Layer Etching (ALET), 22 the top down variant of Atomic Layer Deposition (ALD), has been introduced for fabricating 2D materials. On the other hand, bottom-up techniques have largely been developed using conventional thin film deposition. These techniques include sputtering, evaporation and Chemical Vapor Deposition (CVD). 3,23,24 However, they are mainly based on either high temperature processes, substrate restrictive deposition or low thickness control. 21,25,26 Amongst all the fabrication processes, ALD appears to be one of the most suited techniques to synthesize 2D materials, because of its simplicity, versatility and c...

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3D hierarchical pompon-like Co3O4 porous spheres were produced by a simple hydrothermal method. The 3D structure is composed of many nanowires which gathered as a ring in the centre and fanned out via a special self-assembly fashion, resulting in good lithium ion battery performance.

Developing lithium ion batteries (LIBs) with fast charging/discharging capability and high capacity is a significant issue for future technical requirements. Transition-metal oxide (TMO) materials are widely studied as the next-generation LIB anode to satisfy this requirement due to their specific capacity, nearly three times than that of conventional graphite anode, and low cost. Meanwhile, they also suffer from slow lithium diffusion and limited electrochemical and structural stability, especially at high charging/discharging rate. The structure design of TMO is an effective strategy to obtain desirable LIB performance. Herein, inspired by natural fibrous roots consisting of functional and supporting units that can enhance substances and energy exchange efficiently, fibrous-root-like Zn(x)Co(3-x)O4@Zn(1-y)Co(y)O binary TMO nanoarrays are designed and synthesized on Cu substrates through a facile one-pot, successive-deposition process for use as an integrated LIB anode. In a multilevel array ordered by orientation, ultrafine Zn(x)Co(3-x)O4 nanowire functional units and stable Zn(1-y)Co(y)O nanorod supporting units synergize, resulting in superior rate performance. At a high current density of 500 mAg(-1), they could maintain a discharge capacity as high as 804 mAh g(-1) after 100 cycles, working much higher than unary cobalt-based and zinc-based nanoarrays. This binary synergistic nanoarray system identifies an optimized electrode design strategy for advanced battery materials.