Contents I. Introduction
Home decoration brings a lot of pollution problems with people's demand, which has caused great harm to human health and attracted more and more attention, especially the indoor environment pollution. Ammonia is one of the main sources in the indoor environmental pollution [1], [2]. Ammonia often adsorbs on the surface of the skin due to its high solubility, resulting in irritation and inflammation. Ammonia has a corrosive and irritating effect on the tissues, which denatures the tissue protein, destroying the cell membrane structure. Therefore, it is urgent to conduct the research on gas detection methods with high sensitivity. Semiconductor metal oxide sensors are widely used in gas testing due to their advantages including low cost and easy measurement [4] –[6]. However, the major challenges of this approach are high operating temperature, low sensitivity, and poor selectivity [7], [8]. Recently, many studies have been conducted to improve the response and selectivity of semiconducting metal oxide sensors for volatile organic gases by means of the morphology and microstructure of metal oxides [10]– [12], precious metal modification of metal oxides [13], [14], and the composition with other two-dimensional materials [15]– [17].