Extraordinary room-temperature hydrogen sensing capabilities of porous bulk Pt–TiO 2 nanocomposite ceramics

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

“…The Pd/SnO 2 nanofibers 266 were also synthesized using an electrospinning method, and the sensor made of these nanofibers exhibits super-fast response/recovery times to H 2 (4/3 s to 1000 ppm H 2 ) and an ultralow LOD of 20 ppb. The response of a sensor made of Pt/TiO 2 nanocomposites to 1000 ppm H 2 in N 2 was also reported as high as 6000 at RT, with short response/recovery times of only 10/20 s. 267 Apart from the chemical sensitization and electronic sensitization, there are other mechanisms to enhance the sensing performance of the SMONs: for example, the formation of nano-scale Schottky type junctions between Au nanoparticles and ZnO nanorods and Au sulfidation with high concentrations of H 2 S. 257 Hosseini et al 257 prepared ZnO nanorods using a vapor phase transport method, and found that H 2 S sensing performance has been significantly enhanced at RT after the modification of the surface of ZnO nanorods with Au nanoparticles (see Fig. 16a).…”

Room-Temperature Hydrogen-Sensing Capabilities of Pt-SnO2 and Pt-ZnO Composite Nanoceramics Occur via Two Different Mechanisms

“…Hence what we prepared in this study are composites of SnO 2 and Pt, and ZnO and Pt, separately. It is reasonable that Pt exists in metallic state in those nanoceramics due to the high stability of Pt [ 4 , 15 , 24 ].…”

“…A commercial gas sensor measurement system (GRMS-215, Partulab Com., Wuhan, China) [ 4 ] was used to measure the hydrogen-sensing characteristics of the sintered samples. During the measurement, the room temperature was maintained at 25 °C, and the relative humidity (RH) in air was maintained at about 50%.…”

“…However, they all have to work at elevated temperatures (~500 °C) [ 1 ], which leads to increased energy consumption, shortened service life, and increased safety risks [ 2 ]. In order to develop room-temperature metal oxide (MOX) gas sensors, nano-materials of various MOXs have been synthesized and impressive room-temperature gas-sensing capabilities have been observed for many of them, including SnO 2 [ 3 ], TiO 2 [ 4 , 5 ], WO 3 [ 6 ], Fe 2 O 3 [ 7 , 8 ], ZnO [ 9 , 10 , 11 , 12 , 13 , 14 ]. It is generally believed that the large specific surface of nano-structured MOXs is the key for them to be room-temperature gas sensitive.…”

Calixarene functionalization of TiO2nanoarrays: an effective strategy for enhancing the sensor versatility

“…[15][16][17] Doping noble metals or combining metal oxide semiconductors with inorganic materials such as monolayer MoS 2 is another possible method to enhance the gas sensing ability. [18][19][20] But the selectivity problem is not easy to solve because the sensing mechanism depends on the surface reactions. 21 Because CAs are sensitive and specic for gas detection due to their porous structure, 22 CA functionalization of TiO 2 arrays would become an effective route to improve the hydrogen sensing performance at RT and the selectivity.…”