Interface engineering of ultrananocrystalline diamond/MoS2-ZnO heterostructures and its highly enhanced hydrogen gas sensing properties

High-performance room temperature based hydrogen gas sensor is fabricated using ultra-nanocrystalline diamond/molybdenum disulfide/zinc oxide nanorods (UNCD/MoS2/ZNRs) nanohybrids, through microwave plasma enhanced CVD (MPE-CVD) and hydrothermal techniques. The interfacial effect and structural analysis of UNCD/MoS2/ZNRs layers were comprehensively studied by several analyses. The systematic investigations were revealed that adding MoS2 layer between the ZNRs and UNCD, strongly influence the gas sensing device performance. In addition, the semi-grown UNCD films serve as an excellent substrate for the synthesis of MoS2/ZNRs. Thus the UNCD/MoS2/ZNRs hybrid sensors exhibits the superior sensitivity of 70.6%, which is overwhelmingly superior to that of ZNRs (7.2%). The outstanding improvement is observed due to the efficient material defects and formation of various heterojunction interfaces in the UNCD/MoS2/ZNRs hybrid. It was revealed that the exfoliated MoS2 layer under ZNRs induces more active sites for the adsorption of O-2. Moreover, the chemisorbed O-2 ions in the surface react with H-2, and release a huge number of electrons to the conduction band. Also, the UNCD/MoS2/ZNRs nanohybrid exhibits excellent robustness along with ultra-high gas sensitivity and selectivity due to the addition of semi-continuous UNCD materials. The outstanding features of this UNCD/MoS2/ZNRs nanohybrid potentially extend to nanodiamond and TMD based hybrid materials for future gas sensor/storage applications.