Synergistic effects of α-Fe2O3 nanoparticles and Fe-doping on gas-sensing performance of NiO nanowires and interface mechanism

High surface area nickel oxide nanowires (NiO NWs), Fe-doped NiO NWs and alpha-Fe2O3/Fe-doped NiO NWs were synthesized with nanocasting pathway, and then the morphology, microstructure and components of all samples were characterized with XRD, TEM, EDS, UV-vis spectra and nitrogen adsorption-desorption isotherms. Owing to the uniform mesoporous template, all samples with the same diameter exhibit the similar mesoporous-structures. The loaded alpha-Fe2O3 nanoparticles should exist in mesoporous channels between Fe-doped NiO NWs to form heterogeneous contact at the interface of n-type alpha-Fe2O3 nanoparticles and p-type NiO NWs. The gas-sensing results indicate that Fe-dopant and alpha-Fe2O3-loading both improve the gas-sensing performance of NiO NWs sensors. alpha-Fe2O3/Fe-doped NiO NWs sensors presented the highest response to 100 ppm ethanol gas (55.264) compared with Fe-doped NiO NWs (24.617) and NiO NWs sensors (3.189). The donor Fe-dopant increases the ground state resistance and the absorbed oxygen content in air. alpha-Fe2O3 nanoparticles in electron depletion region result in the increasing resistance in ethanol gas and decreasing resistance in air. In this way, alpha-Fe2O3/Fe-doped NiO NWs sensor presents the excellent gas-sensing performance due to the formation of heterogeneous contact at the interface.

Automated summary

High surface area nickel oxide nanowires (NiO NWs), Fe-doped NiO NWs and alpha-Fe2O3/Fe-doped NiO NWs were synthesized with nanocasting pathway and characterized with various techniques. Fe-dopant and alpha-Fe2O3-loading improved gas-sensing performance of the sensors, with alpha-Fe2O3/Fe-doped NiO NWs sensors showing the best response to ethanol gas due to the formation of heterogeneous contact at the interface. The sensors with uniform mesoporous structures exhibited enhanced gas-sensing properties.