Synthesis of High Entropy Oxide through Sol-Gel Method

High entropy oxides composed of Ag, Al, Zn, Cr, and Cu are synthesized through sol-gel method. The metal nitrates, including silver nitrate, aluminum nitrate, zinc nitrate, chromium nitrate, and copper nitrate, are firstly dissolved in distilled water and stirred for one hour at room temperature. After mixing thoroughly, citric acid will be added into the solution as the coordinating agent to catch all metal atoms and stirred for another half an hour. Then, by adding ammonia, the pH value of the solution is adjusted to seven and the solution is dried in the oven at 90 o C for 48 hours. After that, the powder was annealed at 300 o C for one hour to obtain the final product. The x-ray diffraction pattern shows that AgAlZnCrCuO exhibited a single-phase spinel structure with the second phase of CuO. Interestingly, based on the scanning electron microscope image, the AgAlZnCrCuO nanoparticles show highly porous morphologies, suggesting that the AgAlZnCrCuO may possess the unique potential application for electrochemical process.