Expanding the interlayers of molybdenum disulfide toward the highly sensitive sensing of hydrogen peroxide

Abstract

Expandable interlayers in two-dimensional (2D) transition metal dichalcogenides enable the regulation of physicochemical properties toward boosted applications. Herein, interlayer-expanded MoS₂ (IE-MoS₂) was designed as a sensitive electrochemical biosensor for H₂O₂via a one-step hydrothermal process employing excessive thiourea. This facile fabrication successfully avoids the complicated manipulations in conventional exfoliation-resembling strategies. The as-obtained IE-MoS₂ features an expanded interlayer-spacing of 9.40 Å and metallic electronic configurations. Thereby, it possesses good conductivity and more importantly enhanced binding with the *OH intermediate, accomplishing a fast kinetics of H₂O₂ reduction (H₂O₂ + 2e⁻ → 2OH⁻) and consequently a sensitive response in electrochemical H₂O₂ sensing. The optimal IE-MoS₂ affords a high sensitivity (1706.0 μA mM⁻¹ cm⁻²) and a low detection limit (0.2 μM), outperforming the non-expanded MoS₂ (738.0 μA mM⁻¹ cm⁻², 1.0 μM) and most of the previously reported materials free from enzymes. Moreover, it performs well in real samples and in the presence of various interfering substances and can be used to measure the intracellular H₂O₂ amount of cancer cells; this suggests the possible applications of IE-MoS₂ in real-time monitoring, clinical diagnosis and pathophysiology. This study will inspire the rational design of 2D sensing materials via regulation of their interlayer chemistry.