Enhanced Electrochromic Properties of NiOx Films Through Magnesium Doping Strategy

In order to improve the electrochromic properties of NiO<i>_x</i> films, Mg ions were introduced into NiO<i>_x</i> films using the sol-gel method and the spin-coating method. The introduction of Mg ions leads to the loose structure of the compact NiO<i>_x</i> 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 NiO<i>_x</i> film, which effectively increases the reactive sites and improves the charge transfer efficiency at the interface between the NiO<i>_x</i> film and the electrolyte. The electrochemical results further show that the film electrode (NiO<i>_x</i>-Mg2) has the largest charge storage capacity when the Mg doping concentration is 10%. Compared with the undoped NiO<i>_x</i> film, the doping of Mg improves the transmittance modulation (Δ<i>T</i>) performance of the NiO<i>_x</i> film (Δ<i>T</i> 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 NiO<i>_x</i> films.