## 1 Introduction  
The need for air dehumidification for the preservation of art, products and equipment in different industries has led to the development of various dehumidifying mechanisms over the past few years [1; 2; 3; 4; 5; 6; 7; 8]. Many dehumidification technologies are bulky, energy-inefficient or noisy, and they cannot be used with precision equipment that requires a small footprint and noise-free operation. An example of this kind of equipment is a Fourier-transform infrared (FTIR) spectrometer [9]. Most commercial FTIR spectrometers use hygroscopic materials such as potassium bromide (KBr), which can degrade very quickly in high humidity environments if no dehumidifying mechanism is present [10]. Water vapor absorption can also interfere with the spectral measurements of these instruments and introduce noise [11]. At the same time, the dehumidifier is not allowed to produce high-frequency noise or vibrations that would result in distortions in the measured FTIR spectra. The most common and affordable solution for this kind of equipment is the use of silica gel desiccants [12; 13; 14; 15; 16], which can also be found in electronics, clothes, and food products. Silica gel desiccants are non-toxic small beads, whose composition is mostly silicon dioxide with a porous structure, offering a large adsorption area. They can be packed in a confined space and adsorb the surrounding moisture. The drawback of such a configuration is the short \"lifetime\" of the silica gel desiccants, which leads to the need for continuous monitoring of their condition and the need for frequent replacement once they are saturated with moisture. Several other compact and noiseless materials and devices with similar or advanced moisture-removing properties have been reported. These include hygroscopic salts integrated in porous structures, 2D nanosheets of metal-organic frameworks (MOF) and hydrophilic sponges composed of rigid gel and hygroscopic materials [17; 18; 19]. While hygroscopic salts integrated in porous structures face engineering challenges in the context of maximizing dehumidification performance, devices based on 2D MOF nanosheets show great promise due to their effective adsorption and their ease of fabrication. On the other hand, hydrophilic sponges not only exhibit high humidity-capturing capacities, but they can also act as visual humidity sensors, due to their color changing ability in different humidity levels. The latter property is also a feature of silica gels. Nevertheless, these technologies still experience difficulties in mass adaptation, and they are a field of ongoing research. Moreover, they still require dehydration or substitution after excessive use. An alternative technology that has attracted increasing interest in the past few years is ionic membranes [20; 21; 22; 23; 24; 25; 26; 27]. These devices work based on electrolysis, and they typically comprise a proton-conductive electrolytic layer sandwiched between two porous electrodes with catalytic layers composed of noble metal particles. The electrolytic layer can be ceramics (i.e., SrCeO\({}_{3}\)) [28] or polymer composites (i.e., Nafion117 and NEXAR\({}^{\circledR}\), Kraton Polymers Llc., Houston, TX, USA) [29; 30; 31]. As shown in Figure 1a, when a DC voltage is applied to the electrodes, the water vapor in the dehumidifying anode side boundary is decomposed into H\({}^{+}\) cations and O\({}_{2}\). The H\({}^{+}\) cations pass through the electrolytic layer and recombine with O\({}_{2}\) molecules in the humidifying cathode side boundary to form H\({}_{2}\)O. The reactions that occur at the boundaries of the two electrode sides are given by the following equations:  
\[\text{Anode--2H}_{2}\text{O}\to 4\text{H}^{+}+4\text{e}^{-1}+\text{O}_{2} \tag{1}\] \[\text{Cathode--4H}^{+}+4\text{e}^{-1}+\text{O}_{2}\to 2\text{H}_{2} \text{O} \tag{2}\]  
In general, ionic membranes provide vibration- and maintenance-free operation, compact sizes, long operating lives and low power consumption.