Space-confined synthesis of SWNT bundles wrapped by MoS2 crystalline layers as flexible sensors and detectors

Single-walled carbon nanotubes (SWNTs) are ideal template for constructing one-dimensional (1D) heterojunctions with intriguing optical and electrical properties, yet it remains challenging to wrap foreign materials around SWNTs due to their very small diameter and large curvature. Here, we present a space-confined method to synthesize SWNT bundles wrapped by MoS2 crystalline layers (SWNT@MoS2) film by embedding a pristine SWNT film within a porous multi-walled nanotube sponge, which acts as a liquid precursor container for hydrothermal reaction. We find that crystalline MoS2 sheets could be formed around the outer surface of SWNT bundles uniformly and continuously, with tailored number of multi-layers (3–17 layers), for bundle sizes ranging from several to hundreds of nanometers. The resulting SWNT@MoS2 network shows much enhanced light response and gas sensitivity, presenting promising applications as flexible photo-detectors and toxic gas sensors. Our scalable synthesis method and SWNT-based coaxial-cables will be useful in future developing innovated 1D van der Waals heterojunctions and flexible nanoelectronic systems. Crystalline MoS2 sheets could be formed around the outer surface of SWNT bundles uniformly and continuously, for bundle sizes ranging from several to hundreds of nanometers, with 1D vdW structures distinct from previously reported. [Display omitted] •A space-confined method to synthesize SWNT@MoS2 film by embedding a pristine SWNT film within a porous multi-walled nanotube sponge.•Crystalline MoS2 sheets could be formed around the outer surface of SWNT bundles uniformly and continuously, with tailored number of multi-layers (3–17 layers), for bundle sizes ranging from several to hundreds of nanometers.•The SWNT@MoS2 heterojunctions based on SWNT bundles with different sizes are distinct from previously reported 1D vdW structures based on a single SWNT or multi-walled nanotube.•The as-synthesized SWNT@MoS2 films preserved their original structural flexibility and can be used as flexible sensors and detectors.