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

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.