Enhanced Electrochromic Properties of NiOx Films Through Magnesium Doping Strategy

In order to improve the electrochromic properties of NiOx films, Mg ions were introduced into NiOx films using the sol–gel method and the spin-coating method. The introduction of Mg ions leads to the loose structure of the compact NiOx film, which can provide more channels for the transport of OH−. In addition, the introduction of Mg ions increases the oxygen vacancies and oxygen interstitial defects in the NiOx film, which effectively increases the reactive sites and improves the charge transfer efficiency at the interface between the NiOx film and the electrolyte. The electrochemical results further show that the film electrode (NiOx-Mg2) has the largest charge storage capacity when the Mg doping concentration is 10%. Compared with the undoped NiOx film, the doping of Mg improves the transmittance modulation (ΔT) performance of the NiOx film (ΔT up to 55.8%) and shortens the response time (2.39 s/0.63 s for coloring/bleaching). In general, Mg doping is an effective method for improving the electrochromic properties of NiOx films.