Selective H2S sensing characteristics of CuO modified WO3 thin films

Ultrasensitive and ultraselective detection of H2S using electrospun CuO-loaded In2O3 nanofiber sensors assisted by pulse heating

“…or by the formation of hetero-nanostructured composites between oxide additives/catalysts and chemiresistive materials [29][30][31]. The ptype CuO is a representative oxide additive to enhance the H 2 S sensing characteristics of n-type oxide semiconductors, such as SnO 2 [32], ZnO [33], WO 3 [34], and MoO 3 [35]. The high H 2 S sensing characteristics observed in CuO-loaded n-type oxidesemiconductor materials have been attributed to the change of the resistive hetero-junction between p-type CuO and n-type oxide semiconductor into a conductive junction between metallic CuS and n-type oxide semiconductor, because of the strong chemical interaction between CuO and H 2 S [36].…”

H2S Sensing in Dry and Humid H2 Environment With p-Type CuO Thick-Film Gas Sensors

“…The effect of exposure to reducing gases, like H2S is the reduction of the negative charge trapped at the surface of the metal oxide O − (ads) [13,29]:…”

“…These reactions compete with a second type of reaction that is probably less dominant for the temperature range used in our experiments and could be described as [13]: CuO + H2S → CuS(surface) + H2O(gas)…”

“…As the water vapour injection is withdrawn desorption process is expected to occur at the surface which can be described as [28]: OH(ads) → H2O(ads) + Oο(surface) → H2O(gas) + Oο(surface) (13) Temperature is also important factor for metal oxide gas sensors. Typical curves of gas response at operating temperature ranging from 150 °C to 400 °C in humid environment are presented in Figure 5 (a-d).…”

“…Only a few reports have been published on the mechanism of the response of MOX sensors in the absence or at trace levels of oxygen concentrations and these sensors employ mainly n-type metal oxides, such as WO3 and SnO2 [7][8][9][10][11]. Among p-type MOX semiconductors, CuO has received some attention for hydrogen sulfide (H2S) detection in air [12][13][14][15][16]. This gas is one of the highly toxic and flammable gases and is widely needed in industrial processes.…”