## 1 Introduction  
Air pollution produced by the emission of gases such as CO, CO\({}_{2}\), CH\({}_{4}\), C\({}_{3}\)H\({}_{8}\), SO\({}_{2}\), and H\({}_{2}\)S, among others [1; 2; 3], has caused a substantial decrease in the quality of life of humans and other species. This emission of toxic gases into the atmosphere of large cities by industries and internal combustion engines is considered to be the main cause of diseases due to respiratory and cardiovascular nature, not to mention the greenhouse effect and the ecological and environmental imbalance they also provoke [4; 5; 6; 7; 8; 9]. To mitigate the damage, it is necessary to have better control of the concentrations of harmful gases. For this purpose, different binary semiconductor oxides, such as SnO\({}_{2}\), Mn\({}_{2}\)O\({}_{3}\), GeO\({}_{2}\), MoO\({}_{3}\), and Nb\({}_{2}\)O\({}_{5}\), among others, have been investigated in the past [10; 11; 12]. It has been recently suggested that ternary semiconductor oxides are strong candidates to be applied as gas sensors [13; 14; 15; 16]. Among these materials, we can find the perovskite (e.g., LaFeO\({}_{3}\)) [17] and the spinel (e.g., CuFe\({}_{2}\)O\({}_{4}\)) type structures [18]. On the other hand, other studies report that semiconductor oxides with trirutile-type structure possess interesting detection properties since they are chemically stable and can operate at different temperature ranges (mainly between 200 and 350 \({}^{\circ}\)C) [19]. The trirutile-type oxides most commonly employed for this application are CuSb\({}_{2}\)O\({}_{6}\)[20], NiSb\({}_{2}\)O\({}_{6}\)[21], MgSb\({}_{2}\)O\({}_{6}\)[22], ZnSb\({}_{2}\)O\({}_{6}\)[23], and more recently CoSb\({}_{2}\)O\({}_{6}\)[24]. It has been established that the high efficiency and good response of semiconductor materials for detecting toxic gases are mainly due to their morphology and porosity, and the nanometric size of the particles [19; 22]. To obtain this type of microstructural features, different synthesis routes have been used in the past, like the solid-state reaction, hydrothermal, coprecipitation, and sol-gel processes [25; 26; 27]. On the other hand, the colloidal synthesis method has been increasingly employed because through this process it is possible to obtain porous surfaces, diverse morphologies (nanoparticles, nanowires, nanorods, and nanobelts), and particle sizes less than 100 nm [22; 23; 24]. The NiSb\({}_{2}\)O\({}_{6}\) oxide was applied for the Liquefied Petroleum Gas (LPG) and Carbon dioxide (CO\({}_{2}\)) detection. The oxide was synthetized using a via sol-gel spin coating method. In the experimental work, the electrical resistance changed when the NiSb\({}_{2}\)O\({}_{6}\) oxide was exposed to LPG and CO\({}_{2}\). The measurement concentrations were into the interval of 1000 until 5000 ppm [21]. In reference [28], the authors proposed a chemical detector based on NiSb\({}_{2}\)O\({}_{6}\) oxide. The NiSb\({}_{2}\)O\({}_{6}\) powders were synthetized using the microwave-assisted colloidal method. In the experiments, propane (C\({}_{3}\)H\({}_{8}\)) and Carbon monoxide (CO) were detected, the concentrations were between 0 and 300 ppm, the operation temperatures were from 100 to 300 \({}^{\circ}\)C and the maximum sensitivity was approximately 2.14 (to 300 \({}^{\circ}\)C). On the other hand, using the microwave-assisted wet chemical method, the chemical sensor based on the NiSb\({}_{2}\)O\({}_{6}\) oxide was better. The sensitivity was increased from 2.1 to 14.1 (to 300 \({}^{\circ}\)C) [29]. Again, in the experimental work, C\({}_{3}\)H\({}_{8}\) and CO were used and the concentrations were between 0 and 300 ppm. However, to our knowledge, the signal adaptation was not proposed for the chemical sensor based on the NiSb\({}_{2}\)O\({}_{6}\) oxide. In this work, the nickel antimonite (NiSb\({}_{2}\)O\({}_{6}\)) oxide was synthetized, characterized and applied as a chemical sensor for the carbon monoxide detection.