Co3O4/ZnO nanocomposites for gas-sensing applications

Synthesis of TiO2 decorated Co3O4 acicular nanowire arrays and their application as an ethanol sensor

“…The on and off gas response process can be explained by gas adsorption, surface chemical reaction and desorption, which lead to signicant electrical conductivity changes resulting from the chemical interaction of gas molecules with the oxygen species on its surface. 26 At the optimal operating temperature, the adsorption of negatively charged oxygen can generate plenty of holes for the conduction, which leads to the formation of a charge accumulation layer on the surface of Co 3 O 4 . When the sensor is exposed to ethanol, the oxygen species on Co 3 O 4 could promote the oxidation of ethanol gas molecules to CO 2 and H 2 O.…”

“…2,[22][23][24] Recently, it has been found that designing a p-n junction by combining Co 3 O 4 with other n-type semiconductors would be a signicant route to enhance its gas response. 12,[25][26][27][28] In the heterogeneous region, the p-type semiconductor Co 3 O 4 and the n-type semiconductor TiO 2 can form a self-built electric eld, and establish a depletion layer. When exposed to air, the hole density on the surface of the Co 3 O 4 increase while the electrons on the surface of the TiO 2 decrease due to the ionization of absorbed oxygen species, which leads to a lower resistance of the Co 3 O 4 .…”

Synthesis, structure and ethanol sensing properties of Ga2O3-core/WO3-shell nanostructures

“…Reactions (1) and (2) The enhanced response, faster recovery and enhanced selectivity of the Ga 2 O 3 -core/WO 3 -shell nanostructure sensor compared to those of the pristine Ga 2 O 3 nanostructure sensor could be explained by a combination of a surface-depletion mechanism [18,19] and a potential barrier-controlled carrier transport mechanism [20,21]. Regarding the surface-depletion mechanism, upon exposure to air, a depletion layer is created in the surface region of the nanostructure sensor.…”

Fabrication and NO2 gas sensing performance of TeO2-core/CuO-shell heterostructure nanorod sensors

“…The fabrication of heterostructures [6-8] is a promising technique to improve the sensitivity of the 1D nanostructured sensors. The improved sensing performance of the heterostructured 1D sensors has been attributed to a range of factors including increased potential barriers at the interface of the heterostructure [9,10], modulated depletion layer [11,12], band bending due to equilibration of the Fermi energy levels [13], synergistic surface reactions [14], etc.…”