Gasochromic α,β-Ni(OH)2 films for the determination of CO and chlorine content

- α-Ni(OH)2 and α, β-Ni(OH)2 films have been obtained by cathodic deposition.
- Chemical interaction Ni(OH)2 films with CO or Cl2 leads to a change in their color.
- These properties films were used for the determination of CO and Cl2.

The studies of the kinetics of optical conversions in α-Ni(OH)2 and α, β-Ni(OH)2 modification films under the influence of CO and Cl2 showed that their color change is due to the redox reactions of Ni(OH)2 or NiO(OH) in the interaction with the gas-oxidant (Cl2) or reductant (CO). The action of CO leads to a partial reduction of NiO(OH) to Ni(OH)2 and establishment of an equilibrium state of light transmission wavelength λ = 500 nm. The volume content of CO was determined from the value of light transmission. The action of chlorine on a Ni(OH)2 film moistened with a 0.1 M NaOH solution leads regardless of its percentage in the air to complete of oxidation Ni(OH)2. The chlorine volume content was determined from the rate of chemical oxidation of Ni(OH)2 by NaOCl solution, which is formed on the film surface. It has been found that the thin films with Ni(OH)2 structure react for 1 min to the presence of CO and chlorine (by changing their colorations). Thick films of mixed α-Ni(OH)2/β-Ni(OH)2 structure are more slowly decolored for 2-4 min by CO and are colored within 1-2 min by chlorine.