Synthesis and characterizations of zinc oxide nanoparticles and its ability to detect O2 and NH3 gases

Pd-Decorated ZnO Hexagonal Microdiscs for NH3 Sensor

“…Gas-sensing materials are crucial for gas sensors. For widely reported semiconductor NH 3 sensors, the NH 3 gas-sensing materials mainly include polyaniline (PANI) and its composites [1,[7][8][9], oxides (ZnO, SnO 2 , and TiO 2 ) and their composites [10][11][12][13][14][15][16], and other composite materials. Among them, the PANI-based gas sensors have good selectivity for NH 3 and can operate at room temperature, but their response/recovery speed and stability are insufficient [1,3,[5][6][7][8][9].…”

“…Among them, the PANI-based gas sensors have good selectivity for NH 3 and can operate at room temperature, but their response/recovery speed and stability are insufficient [1,3,[5][6][7][8][9]. Until now, the oxides and their composites are still the mainstream gas-sensing materials in the field of semiconductor NH 3 sensors due to their fast response/recovery speed and good stability [10][11][12][13][14][15][16]. Among various oxide gas-sensing materials, n-type ZnO with a wide bandgap (3.37 eV) and good thermal/chemical stability and its composites have been frequently used for developing semiconductor NH 3 sensors [10][11][12][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”

“…Until now, the oxides and their composites are still the mainstream gas-sensing materials in the field of semiconductor NH 3 sensors due to their fast response/recovery speed and good stability [10][11][12][13][14][15][16]. Among various oxide gas-sensing materials, n-type ZnO with a wide bandgap (3.37 eV) and good thermal/chemical stability and its composites have been frequently used for developing semiconductor NH 3 sensors [10][11][12][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The NH 3 sensing performances of the bare ZnO are usually poor [10][11][12].…”

“…Among various oxide gas-sensing materials, n-type ZnO with a wide bandgap (3.37 eV) and good thermal/chemical stability and its composites have been frequently used for developing semiconductor NH 3 sensors [10][11][12][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The NH 3 sensing performances of the bare ZnO are usually poor [10][11][12]. Firstly, by selecting different materials and constructing ZnO composites, it is a conventional strategy to improve the NH 3 -sensing performance of ZnO-based NH 3 sensors, such as poly(3-hexylthiophene)/ZnO [17], polymethyl methacrylate/reduced graphene oxide (rGO)/ZnO [19], carbon/ZnO [20,27], poly-o-methoxyaniline/ZnO [21], rGO/ZnO [23], CuO/ZnO [25], CuPc/ZnO [26], rGO/ZnO/Si [28], and WO 3 •H 2 O/ZnO [29].…”

One-pot synthesis of novel chitosan-salicylaldehyde polymer composites for ammonia sensing

“…Upon injecting ammonia, the adsorbed oxygen species react with the NH 3 molecules forming H 2 O, N 2 , and three electrons which are injected into the conduction band of ZnO NPs by decreasing the depletion layer width and decreasing sensor resistance as a result. Upon the recovery of the sensor, the adsorbed ammonia molecules get desorbed from the ZnO NPs surface and increase the depletion layer width again and the resistance of the sensor is increased and returns to the initial baseline value 38 . The mechanism of the process is expressed by the following equations: …”