Synthesis of nanograined ZnO nanorods functionalized with NiO nanoparticles and their enhanced hydrogen sensing properties

NiO nanoparticle (NP)-functionalized nanograined ZnO nanorods (NRs) were grown by using the thermal evaporation of ZnSe powders; this was followed by the thermal oxidation of the ZnSe NRs to synthesize ZnO NRs and a solvothermal process for NiO functionalization. The diameters of the grains in the synthesized nanograined ZnO NRs are in the range of 50-150 nm. The ZnO grains were not spherical, but they were shaped like rice grains. The diameters and the lengths of the ZnO NRs were in the range of 40-50 nm and 1-6 mu m, respectively. The diameters of the NiO NPs were in the range of 40-80 nm. A multiple-networked chemiresistive sensor was fabricated by pouring the IPA solution containing NiO NP-decorated nanograined ZnO NRs onto SiO2/Si substrates with a patterned electrode. A pristine nanograined ZnO NR sensor was also prepared in a similar manner. The NiO NP-functionalized nanograined ZnO NR sensor exhibited a greater and faster response to H-2, as compared to its pristine nanograined ZnO counterpart; it also showed higher selectivity toward H-2 against other reducing gases, as compared to the pristine nanograined ZnO counterpart. Herein, the origin of the enhanced sensing performance of the NiO NP-functionalized nanograined ZnO sensor is discussed in detail.