Abstract To control the growth of layered two-dimensional transition metal dichalcogenide (TMD) materials or complex structures such as heterostructures, it is important to understand the growth mechanism. In this study, we demonstrated the chemical vapor deposition (CVD) growth of vertically aligned MoO2/MoS2 flakes by using sulfur and molybdenum trioxide (MoO3) powders as precursors. Moreover, based on various experimental measurements, a detailed growth mechanism is proposed for elucidating the conversion of MoO2 to MoS2 in the CVD process to achieve vertically aligned MoO2/MoS2 flakes. Our results reveal that two competing pathways for sulfurization reactions occur during the CVD growth process: the dominance of the reactions in the vapor-phase pathway facilitates the formation of parallel-aligned MoS2 flakes, while the dominance of the reactions in the solid-phase pathway determines the formation of vertically aligned MoO2/MoS2 flakes. In addition, the photoelectrochemical (PEC) activity of the vertically aligned MoO2/MoS2 flakes was evaluated for hydrogen production applications based on PEC water splitting. Our results open the door to promote the process for designing the growth of other TMD materials or complex structures, which can be beneficial for use in various applications.

中文翻译：

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阐明垂直 MoO2/MoS2 薄片化学气相沉积生长的光电化学应用机理

摘要 为了控制层状二维过渡金属二硫属化物 (TMD) 材料或复杂结构（如异质结构）的生长，了解其生长机制非常重要。在这项研究中，我们展示了通过使用硫和三氧化钼 (MoO3) 粉末作为前体，垂直排列的 MoO2/MoS2 薄片的化学气相沉积 (CVD) 生长。此外，基于各种实验测量，提出了详细的生长机制，以阐明在 CVD 过程中 MoO2 向 MoS2 的转化，以实现垂直排列的 MoO2/MoS2 薄片。我们的结果表明，在 CVD 生长过程中发生了两种硫化反应的竞争途径：气相途径中反应的主导地位促进了平行排列的 MoS2 薄片的形成，而固相途径中反应的主导地位决定了垂直排列的 MoO2/MoS2 薄片的形成。此外，还评估了垂直排列的 MoO2/MoS2 薄片的光电化学 (PEC) 活性，用于基于 PEC 水分解的制氢应用。我们的结果为促进设计其他 TMD 材料或复杂结构的生长过程打开了大门，这对于在各种应用中使用是有益的。