Effect of substrate bending towards chemiresistive based hydrogen gas sensor using ZnO-decorated MgO nanocubes

In this report, a flexible ZnO-decorated MgO nanocubes and core shell type of ZnO/MgO nanocomposite were prepared and used for sensing of hydrogen gas by chemiresistive technique. The preparation of ZnO-decorated MgO nanocubes and core shell type of ZnO/MgO composite was done by two processdchemical vapor deposition followed by drop casting method. Initially, the MgO nanocubes were prepared by chemical vapor deposition methods and then a decoration or creation of shell layer on the surface of MgO nanocubes was optimized by the variation of Zn precursor (1 mol - 3 mol of Zinc acetate dehydrate) during the drop-coating process. The prepared ZnO/MgO composite was characterized using scanning electron microscope, energy-dispersive X-ray analysis, X-ray diffraction, and Fourier transform infrared spece. From this characterization, a one mol of Zn precursor leads to the decoration of ZnO nanoparticle (similar to 100 nm) on the surface of nanocubes. For the 2 mol concentration, the size of ZnO nanoparticle increases from similar to 100 nm to similar to 200 nm. By further increasing the molar concentration of Zn precursor from 2 to 3 mol, the coverage of nanoparticle increases and creates the shell on the core of MgO nanocubes. Therefore, tuning the Zn precursor leads to two different form of composite such as ZnO-decorated MgO nanocubes (1 and 2 mol) and core-shell type of ZnO/MgO nanocomposite (3 mol). The prepared composite was deposited on flexible substrate by doctor blade method and then used for studying H-2 sensing response by chemiresistive method. A maximum response was achieved for 1 mol ZnO/MgO composite (Sensitivity = 1.1459) compared to other concentration ( sensitivity of 0 mol - 1.0858, 2 mol - 1.06 and 3 mol- 1.02) due to the heterojunction formation as well as spillover effect. Further, the flexibility of prepared sensor was studied by varing the bending angle of substrate. From these analysis, the prepared ZnO-decorated MgO nanocubes are well suitable for flexible hydrogen sensor. (c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).