In this study, sputtered-assisted CuO-decorated ZnO nanorod (NR) gas sensors were fabricated for ethanol gas sensing studies. CuO nanoparticles have been successfully formed on ZnO nanorods by means of a physical process as the decorative metallic element. The amount of decoration affecting the sensor’s performance has been optimized. Cu layers with different thicknesses of 5, 10, and 20 nm were deposited on hydrothermally grown ZnO NRs using the sputtering technique. Upon subsequent annealing, Cu was oxidized to CuO. The gas sensing studies revealed that the sensor with an initial Cu layer of 5 nm had the highest response to ethanol at 350 °C. The sensor also showed good selectivity, repeatability, and long-term stability. The enhanced ethanol sensing response of the optimized gas sensor is related to the formation of p-n heterojunction between p-type CuO and n-type ZnO and the presence of the optimal amount of CuO on the surface of ZnO NRs. The results presented in this study highlight the need for optimizing the amount of Cu deposition on the surface of ZnO NRs in order to achieve the highest response to ethanol gas.

Recently, resistive switching memory (RRAM) has been attractive for implementing electronic synapses in neural networks and high-density memory technology. In this paper, we report a different technique for fabricating an Al/GO/ITO RRAM device with multilevel storage capability. In this work, graphene oxide (GO) thin films have been deposited by the spray pyrolysis technique (SPT) using GO powder synthesized by chemical oxidation of graphite flakes via the modified Hummers method. The fabricated RRAM shows good switching performance between On and Off states with the best memory window of 20 and presents reliable retention characteristics of 10 4 s and 50 reproducible write−read DC cycles without degradation. The multilevel feature points out five stable multiresistant states obtained with the variation of the compliance current (I cc ) and reset voltage amplitude. The successful longterm potentiation and depression with 10 ms pulse operation allows to apply this memory in neuromorphic computing applications in addition to 11 gradual conductance levels achieved by continuous set and reset cycles. A comparison of the efficiency of SPT with that of the typical spin coating method showed a notable (87%) yield achieved by SPT. The combination of the multilevel capacity of fabricated RRAMs with SPT was exploited to suggest that GO-based RRAMs have the potential to be used as multibit GO memristors and electronic synapse devices for emerging neuromorphic chips. In addition, this work paves the way for the fabrication of solution-based, low-cost, simple and large-scale GO memristors for future electronics.

A resistive ethanol gas sensor with a high sensitivity has been proposed. The fabricated gas sensor has a very promising response and recovery at room temperature. The proposed sensor has been fabricated by depositing sensitive nanostructured material on printed circuit board interdigitated electrodes. As the sensitive material, ZnO nanorods of high uniformity have been synthesized by hydrothermal method and then decorated by PbS nanoparticles. The synthesized decorated nanorods were characterized by X-ray diffraction and scanning electron microscope which confirmed the formation of the desired nanostructures. The ethanol gas sensing properties of the ZnO nanorods decorated with PdS nanoparticles was measured in a test chamber. The minimum ethanol concentration detected by the sensor has been 10 ppm. The results showed the higher sensitivity of the proposed sensor to the ethanol at room temperature compared to similar works.