Abstract: Disclosed herein are composite films comprising a plurality of nanostructured metal oxide crystals dispersed within a proton conducting polymer phase, wherein the plurality of nanostructured metal oxide crystals have an average particle size of from 1 nm to 20 nm, and wherein the composite film comprises from 20% to 90% by volume of the plurality of nanostructured metal oxide crystals relative to the composite film. The composite film can have a proton conductivity of 10?8 S/cm or more at a temperature of 100° C. or more.

Abstract: Disclosed herein are porous electrochromic niobium oxide films comprising a plurality of niobium oxide nanocrystals, wherein the plurality of niobium oxide nanocrystals comprise niobium oxide having a formula of NbOx where x represents the average Nb:O ratio in the niobium oxide and where x is from 2 to 2.6. Also disclosed herein are methods of making the porous electrochromic niobium oxide films, methods of use of the porous electrochromic niobium oxide films, and devices comprising the porous electrochromic niobium oxide films.