The investigation of high-pressure effects on two-dimensional materials is pivotal for elucidating their distinctive properties and uncovering their potential applications, as pressure can dramatically modify their structural and electronic characteristics. Among these materials, the layered binary monochalcogenide GeS, being isoelectronic and isostructural to black phosphorus, demands an in-depth investigation to reveal its structural and electronic properties under high pressure, thereby enhancing our understanding and potential applications of binary IV-VI monochalcogenides. In this study, we systematically investigate the structural and electrical transport properties of monocrystalline GeS under extreme pressures, reaching approximately 200 GPa, through a combination of computational modeling and experimental techniques. Our findings reveal a phase transition from Pnma to the Cmcm structure at around 35 GPa, followed by a transition to a $Pm\overline{3}m$ structure around 90 GPa. Notably, we observe a metallic-superconductor transition at 44.5 GPa, with a critical temperature ($T_c$) of 3 K, representing experimental evidence of superconductivity in the Cmcm phase of binary IV-VI monochalcogenides. Remarkably, the superconducting behavior of GeS remains robust across the whole studied pressure range, achieving a maximum $T_c$ of 9 K at 193.6 GPa. Furthermore, during the decompression process, we observe an anomalous increase in $T_c$, reaching up to 11 K, highlighting the need for further exploration of other binary IV-VI monochalcogenides and advancing our understanding of superconductivity in layered materials for practical applications.

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• High-pressure studies
• Superconductors
• Layered crystals
• Superconductivity
• First-principles calculations
• Pressure techniques