To improve the NO 2 -sensing performance of single-walled carbon nanotube (SWCNT)-based sensors, zinc oxide (ZnO) nanoclusters (NCs) were functionalized by a microwave (MW)-assisted synthesis technique. Gas sensors based on pristine SWCNTs and ZnO NC–SWCNT composites synthesized using different weight ratios (ZnO/SWCNTs = 0.5:1, 1:1, 2:1, and 3:1) were fabricated, and their ability to sense various gases at room temperature (25 °C) was investigated. The results showed that the sensing performance of the ZnO NC–SWCNT composite synthesized with a weight ratio of 1:1 (denoted as Z-SWCNTs) was significantly enhanced with respect to NO 2 response and selectivity. This enhanced sensing performance is thought to be a result of both the modulation of the conduction channel at the ZnO NC–SWCNT heterointerfaces and the generation of defects (or holes) by MW irradiation that act as active sites for the target gases. The results obtained in this work provide not only a facile method of cofunctionalizing oxide NCs and defects but also a new methodology for improving the sensing capabilities of SWCNT-based gas sensors.

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Electrodeposition of Pd provides excellent chemical and low‐contact resistance with good electrical properties, such as different types of electrical contacts in the electronics industry. The conventional Pd plating process utilizes ammonia‐based electrolytes. Ammonia was added continuously to maintain the optimum pH range in Pd electrolyte. In addition, the harmful and strong odor of the evaporating ammonia necessitates the use of a ventilator. A further disadvantage is that the brass substrate is corroded by ammonia vapor, and the corrosion products can contaminate the electrolytes, thereby changing the technological properties of the deposited plating for the worse. Ethylenediamine has been proposed as an alternative to ammonia; however, Pd electrodeposition occurs as microcracks via hydrogen evolution. In this study, the effects of Pd electrolyte on ethylenediamine as a complexing agent and the properties of various additives are investigated to improve current density and internal stress in Pd electrodeposition that occurs on a brass substrate. Therefore, complexing agents such as 3‐pyridine sulfonic acid, sodium nicotinate, butyne 1–4 diol, and sodium allylsulfonate are selected as additives, to serve as an alternative to ammonia in Pd electrolyte. In this study, the properties of electrodeposited Pd with various additives were examined. The effect of additives on Pd electrolytes can be classified as dense surfaces without defects such as microcracks and pinholes, which improved surface roughness and corrosion resistance. Particularly, Pd electrolyte using sodium nicotinate has relatively improved surface roughness and properties. Pd electrolyte was optimized under ammonia‐free conditions by the addition of sodium nicotinate.