Pure and Au-decorated sub-micrometer ZnO spheres were successfully grown on glass substrates by simple chemical bath deposition and photoreduction methods. The analysis of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, energy-dispersive X-ray spectroscopy (EDS), UV–vis absorption, and photoluminescence (PL) spectra results were used to verify the incorporation of plasmonic Au nanoparticles (NPs) on the ZnO film. Time-resolved photoluminescence (TRPL) spectra indicated that a surface plasmonic effect exists with a fast rate of charge transfer from Au nanoparticles to the sub-micrometer ZnO sphere, which suggested the strong possibility of the use of the material for the design of efficient catalytic devices. The NO2 sensing ability of as-deposited ZnO films was investigated with different gas concentrations at an optimized sensing temperature of 120 °C. Surface decoration of plasmonic Au nanoparticles provided an enhanced sensitivity (141 times) with improved response (τRes = 9 s) and recovery time (τRec = 39 s). The enhanced gas sensing performance and photocatalytic degradation processes are suggested to be attributed to not only the surface plasmon resonance effect, but also due to a Schottky barrier between plasmonic Au and ZnO structures.

In this paper, research on a CO catalytic gas sensor based on nano-crystalline perovskite oxide NdFeO 3 designed for exhaust gas measurement is presented. Nano-crystalline oxide NdFeO 3 was synthesized by a sol–gel citrate technique. The gas sensing characteristics of this sensor were investigated in the concentration range of CO between 0 and 5 vol.% in air. The influences of C 3 H 8, C 4 H 16 gases, relative humidity and air-flow rate on the cross-sensitivity of the CO sensor were also studied.

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In this research, we present the ZnO nanorods synthesized through the simple route of the hydrothermal method. The ZnO nanorods were developed through the application of only zinc acetate Zn(CH3COO)2 and ammonia solution, NH4OH, in the hydrothermal process at 150oC for 10 hours. The size of the ZnO nanorods was defined as approximately 300 nm in diameter and 1-2 μm in length. The fabrication of sensors was achieved through drop-coating of synthesized ZnO nanorods on Al2O3 substrates integrated with Au electrodes. Subsequent to the process of sintering done at 500oC for different durations, ZnO nanorod-based sensors were investigated when exposed to NO2 gas (1.5, 2.5, and 5 ppm) at room temperature under continuous UV-LED (385 nm) illumination. The correlation between NO2 gas sensing performance and the optical property of the ZnO nanorods is discussed in detail. Herein, the defect concentration, particularly in the surface region of the ZnO nanorods could be modified through sintering, and this indicates its importance in the reduction of response-recovery times and enhancement of high sensitivity to NO2 gas.