Ni-doped Co3O4 the influence of different exposed crystal facets and doping amount on the humidity sensitivity: Experiment and theory

Water vapor causes the baseline resistance, response, recovery time, and long-term stability of the metal oxide semiconductor (MOS) gas sensors to change in different humidity. Combining first-principle and experimental can provide an in-depth understanding of the sensing mechanism from the atomic and molecular scales. In this work, we examined the humidity sensitivity of different concentrations of Ni-doped Co 3 O 4 in detail. Co 48 O 64 (1   1   0) and Co 48 O 64 (1   1   1) were constructed by HR-TEM and doped with single, double, and treble Ni atoms on both surfaces. We calculated the adsorption of water and n-butanol molecule on these eight surfaces. The results show that Ni doping improves the moisture resistance properties of Co 48 O 64 (1   1   0) and Co 48 O 64 (1   1   1), and the sensing properties of C 3 H 9 OH adsorbed on Ni 2 Co 46 O 64 (1   1   0) and Ni 2 Co 46 O 64 (1   1   1) are higher than single and treble Ni atoms doping. To investigate the humidity sensitivity further, we synthesized nanorods Co 3 O 4 with and without Ni doping. The experimental results showed that the humidity sensitivity of Ni-Co 3 O 4 was significantly lower than that of Co 3 O 4 . The decrease in the response value for the C 3 H 9 OH may be attributed to the change in the concentration of the Ni doping or the difference in the primarily exposed crystal facet.