Green growth of mixed valence manganese oxides on quasi-freestanding bilayer epitaxial graphene-silicon carbide substrates
Green growth of mixed valence manganese oxides on quasi-freestanding bilayer epitaxial graphene-silicon carbide substrates
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DOI：
10.1016/j.mtadv.2024.100467
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发表时间：
2024-01-26
影响因子：
10
通讯作者：
Daniels，Kevin M.
中科院分区：
文献类型：
--
作者：
Pedowitz，Michael;Lewis，Daniel;Daniels，Kevin M.
纳米结构锰氧化物（MnOx）在构建下一代储能和催化系统方面显示出令人难以置信的前景。然而，由于苛刻的沉积条件和较差的结构稳定性，与其他低维材料集成已被证明具有挑战性。在这里，我们报告了使用简单的三步电化学过程在双层外延石墨烯（QEG）上沉积层状二氧化锰（δ-MnO 2），该过程不涉及苛刻的化学品。利用该工艺，在1.25s内即可合成出厚度为50 nm的H-MnO_2薄膜。这种合成水钠锰矿本身具有水稳定性，这在文献中首次报道。我们还证实，这一过程不会造成结构损伤的QEG，证明了缺乏D峰形成。这种QEG异质结构增强了MnO 2的氧化还原活性气体传感，使室温下检测NH3和NO2。我们还报告了通过温和退火将这种δ-MnO 2转化为其他MnOx化合物Mn 2 O3和Mn 3 O 4。这通过膜的拉曼光谱证实，这也证实了对QEG基底的有限损伤。据我们所知，这是第一次在原始石墨烯衬底上合成Mn 2 O3和Mn 3 O 4。这两种方法都证明了使用QEG衬底在单晶石墨烯上沉积和转化多功能氧化物的潜力，从而形成以前看不见的纳米结构异质结构。此外，沉积的电化学性质提供了将该工艺扩展到QEG晶片并调节溶液以产生其他强大的多功能氧化物的能力。
Nanostructured manganese oxides (MnOx) have shown incredible promise in constructing next-generation energy storage and catalytic systems. However, it has proven challenging to integrate with other low-dimensional materials due to harsh deposition conditions and poor structural stability. Here, we report the deposition of layered manganese dioxide (δ-MnO2) on bilayer epitaxial graphene (QEG) using a simple three-step electrochemical process involving no harsh chemicals. Using this process we can synthesize a 50 nm thick H–MnO2film in 1.25s. This synthetic birnessite is inherently water-stabilized, the first reported in the literature. We also confirm that this process does not cause structural damage to the QEG, as evidenced by the lack of D peak formation. This QEG heterostructure enhanced MnO2's redox active gas sensing, enabling room temperature detection of NH3and NO2. We also report on transforming this δ-MnO2to other MnOxcompounds, Mn2O3and Mn3O4, via mild annealing. This is confirmed by Raman spectroscopy of the films, which also confirms limited damage to the QEG substrate. To our knowledge, this is the first synthesis of Mn2O3and Mn3O4on pristine graphene substrates. Both methods demonstrate the potential of depositing and transforming multifunctional oxides on single-crystal graphene using QEG substrates, allowing for the formation of nanostructured heterostructures previously unseen. Additionally, the electrochemical nature of the deposition presents the ability to scale the process to the QEG wafer and adjust the solution to produce other powerful multifunctional oxides.