Room-temperature gas sensors are attracting attention because of their low power consumption, safe operation, and long-term stability. Herein, ZnO nanorods (NRs) and nanowires (NWs) were on-chip grown via a facile hydrothermal method and used for room-temperature NO2 gas sensor applications. The ZnO NRs were obtained by a one-step hydrothermal process, whereas the NWs were obtained by a two-step hydrothermal process. To obtain ZnO NW sensor, the length of NRs was controlled short enough so that none of the nanorod-nanorod junction was made. Thereafter, the NWs were grown from the tips of no-contact NRs to form nanowire-nanowire junctions. The gas-sensing characteristics of ZnO NRs and NWs were tested against NO2 gas at room temperature for comparison. The gas-sensing characteristics of the sensors were also tested at different applied voltages to evaluate the effect of the self-activated gas-sensing performance. Results show that the diameter of ZnO NRs and NWs is the dominant parameter of their NO2 gas-sensing performance at room temperature. In addition, self-activation by local heating occurred for both sensors, but because the NWs were smaller and sparser than the NRs, local heating thus required a lower applied voltage with maximal response compared with the NRs.
This work presents the synthesis of the transition metal oxides (micro‐wheels composed of self‐assembled WO3 nanorods, SnO2 nanosheets, and Fe2O3 nanoparticles) by hydrothermal method. The synthesized catalysts are then applied for the regeneration of iodide ions from triiodide ions at counter electrodes (CEs) of dye‐sensitized solar cells (DSCs). As the results, the DSCs with low‐cost catalysts as WO3, SnO2, and Fe2O3 provided an efficiency of 4.36, 4.37 and 1.54 %, respectively, under 1 sun irradiation that is slightly lower than that of a cell with Pt electrode (5.86 %). This behavior is elucidated by electrochemical impedance measurements. These findings provide a strategy to develop low‐cost materials for DSC application.
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