Bifunctional role of PDMS membrane in designing humidity-tolerant H₂S chemiresistors with high selectivity

Abstract

A thermally evaporated hydrophobic PDMS membrane, could significantly mitigate humidity interference/poison (without decline response at 50% RH for nearly 3 months) and enhance the selectivity of CuCrO2 chemiresistor toward erosive...

Delafossite CuGaO2-Based Chemiresistive Sensor for Sensitive and Selective Detection of Dimethyl Disulfide

“…42 Such characteristic effectively alleviates the adsorption/occupation of water molecules onto the CuGaO 2 surface, 43 which ensures the reliable operation of the sensor even under high (up to 90%) humidity levels. In addition, we could observe a rise of base resistance with the increase of RH (Figure 3a); 21,44 similar phenomena have also been observed in other kinds of Cu-based p-type sensors, such as CuCo 2 O 4 and CuCrO 2 . 21,26,44 Under the humid air background, there are several possible water dissociative reaction (or chemisorption) pathways occurring at the MOS surface via the following reaction, 25 where M represents Cu or Ga:…”

“…In addition, we could observe a rise of base resistance with the increase of RH (Figure 3a); 21,44 similar phenomena have also been observed in other kinds of Cu-based p-type sensors, such as CuCo 2 O 4 and CuCrO 2 . 21,26,44 Under the humid air background, there are several possible water dissociative reaction (or chemisorption) pathways occurring at the MOS surface via the following reaction, 25 where M represents Cu or Ga:…”

H2O2-Treated ZnO Nanostructures for Humidity-Tolerant O3 Chemiresistors Operated under Pulsed UV Light Modulation

“…Humidity degradation or even poison poses a challenge for the real application of MOS chemiresistors. 26 Extensive efforts have been devoted to addressing the humidity issue. Operating at relatively high temperatures (i.e., ∼300 to 550 °C) sometimes helps to mitigate humidity interference via "desorbing/repelling" water molecules, at the expense of high power consumption.…”

“…20 However, owing to the intrinsic hydrophilicity of general MOSs (SnO 2 , WO 3 , In 2 O 3 , ZnO, etc. ), 26 surrounding H 2 O molecules from the humid air background could easily adsorb on the surface active sites and cause a drastic degradation or even poison of MOS chemiresistors 27 because the concentration of the surrounding water vapor (e.g., 1207−62604 ppm at relative humidity [RH] 20% at 0 °C to 80% at 38 °C) 28 is typically much higher than the target-gas (O 3 ) concentration. Humidity degradation or even poison poses a challenge for the real application of MOS chemiresistors.…”

“…30 Coating a hydrophobic overlayer (i.e., rare earth oxide CeO 2 , Tb 4 O 7 , or PDMS with intrinsic hydrophobicity) could also help to enhance the humidity resistance to acetone and H 2 S at 100−400 °C. 26,28,31 Though the roomtemperature (RT)-operated chemiresistors possess the unique advantages of low power consumption, simple device structure (without integrating external heater), and compatibility with a flexible substrate, exploring a humidity-resistant, highly sensitive and selective O 3 chemiresistor at RT remains a challenging issue, due to easy occupation of surface active sites by ambient H 2 O molecules preferred at RT and the absence of sufficient activation energy for desorbing them, and UV photoactivation may even accelerate the degradation or poison due to well-known UV-induced hydrophilicity. 32 In this work, we have demonstrated that the RT humidity resistance of the ZnO chemiresistor to O 3 could be drastically improved by a facile H 2 O 2 treatment (denoted as H 2 O 2 − ZnO).…”