LAUSR

DOI: 10.1002/admi.201800071 thin devices. From the past few years, transition metal dichalcogenides (TMDCs) materials analogous to graphene have received captivated attention because of their unconventional mechanical, electrical, physical, and structural properties.[1,2] MoS2, being the frontrunner of TMDC family, has opened up new avenues because of its tunable band gap, a great degree of flexibility, high surface to volume ratio, and its chemical and mechanical robustness.[3,4] Consequently, MoS2 has attained importance in the developement of transistor,[5] water splitting,[6] photodiode,[7] and sensing.[8] MoS2 has also been extensively used as a potential gas-sensing material because of its high selectivity, low detection limit, and having various reactive sites such as sulfur defects, edge sites, and vacancies.[9,10] Nonetheless, incomplete recovery and slow detection to gases at room temperature restrict to MoS2 for practical gas sensing. Moreover, a poor charge transport in MoS2 and an adverse effect of ambiental oxygen and humidity represent the MoS2 limitations for use in advanced applications and must be mitigated.[11,12] In recent years, hybrid MoS2 structures with different morphologies have received considerable attention due to their high sensing performance, exceptional optoelectronic relevance, and potential use in several other low-power applications. For instance, Yin et al. synthesized MoS2–MoO3 hybrid nanomaterial using lithium-exfoliation and as a proof-of-concept this hybrid nanomaterial was used as an active layer for light-emitting diodes.[13] Chen et al. synthesized a strain-gated field effect transistor (FET) hybrid structure consisting of 2D MoS2 flake and 1D ZnO nanowire.[14] A MoS2/SnO2 nanohybrids sensor was reported by Cui et al. for high-performance stable gas sensing in air. Here, the hole injection from SnO2 to MoS2 resulted in better stability of MoS2 toward ambiental oxygen.[15] Chen et al. synthesized a core–shell MoO3–MoS2 nanowires structure to drive a stable hydrogen evolution reaction through a highly efficient mechanism.[16] A partially reduced MoO3 has high conductivity and MoS2 has poor conductivity along particular crystallographic direction. So, MoO3 mitigate the the deficiencies of MoS2 after design a particular architecture. All these investigations depicts that the morphology of the hybrid structures crucially influence A nucleation controlled one-step process to synthesize MoS2–MoO3 hybrid microflowers using vapor transport process and its application in efficient NO2 sensing at room temperature are reported. The morphology and crystal structure of the microflowers are characterized by scanning electron microscope (SEM), Raman, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy techniques. A cathodoluminence mapping reveals that the core of the microflower consists of MoO3, and the flower petals as well as nanosheet are composed of a few layers of MoS2. Further, the MoS2–MoO3 hybrid microflower sensor exhibits a high sensitivity of ≈33.6% with a complete recovery to 10 ppm NO2 at room temperature without any extra stimulus like optical or thermal source. Unlike many earlier reports on MoS2 sensor, this advanced approach shows that the sensor is exhibited a low response time (≈19 s) with complete recovery at room tepmerature and excellent selectivity toward NO2 against various other gases. The efficient conventional sensing of the sensor is attributed to a combination of high hole injection from MoO3 to MoS2 and modulation of a potential barrier at MoS2–MoO3 interface during adsorption/ desorption of NO2. It is believed that the modified properties of MoS2 by such composite could be used for various advanced device applications. Room Temperature Sensors