Edge-Hydrogenated Germanene by Electrochemical Decalcification-Exfoliation of CaGe2: Germanene-Enabled Vapor Sensor

Abstract

<p><a>Two-dimensional germanene has been recently explored for applications in sensing, catalysis, and energy storage. The potential of this material lies on its graphene-like optoelectronic and chemical properties. However, pure free-standing germanene cannot be found in nature and the synthetic methods are hindering the potentially fascinating properties of germanene. </a>Herein, <a>we report for the first time a single-step synthesis of few-layer germanene by electrochemical exfoliation in non-aqueous environment. As a result of simultaneous decalcification and intercalation of the electrolyte’s active ions, we achieved a low-level hydrogenation of germanene that occurs at the edges of the material. The obtained edge-hydrogenated germanene flakes have a lateral size of several micrometers which possess a cubic structure. We have pioneered the potential application of edge-hydrogenated germanene for vapor sensing and demonstrated its specific sensitivity to methanol and ethanol. We have shown a selective behavior of the germanene-based sensor that appears to increase the electrical resistance in the vapors where methanol prevails. We anticipate that these results can provide a new approach for emerging layered materials with the potential utility in advanced gas sensing.</a></p>

Germanium‐based monoelemental and binary two‐dimensional materials: Theoretical and experimental investigations and promising applications

“…The results showed that germanane nanosheets are highly sensitive to volatile organic compounds (VOCs), the biomarker, indicating that germanane nanosheets can be used as molecular devices for detecting liver cirrhosis VOCs (Figure 25E). The most recent work by Kovalska et al 573 demonstrated the edge hydrogenation of germanene by electrochemical decalcification‐exfoliation of CaGe 2 , enabling germanene specific sensitivity to organic vapors, showing selectivity to methanol over ethanol as a sensor. This result confirms the potential of Ge‐based 2D materials as gas sensors.…”