Ammonium metavanadate nh4vo3

All the chemicals were purchased from Merck and used without further purification. The vanadium oxide powders (V₂O₅) were synthesized using a modified sol–gel technique. Ammonium metavanadate (NH₄VO₃, 99.0%, Sigma-Aldrich) was first dissolved in deionized water for 2 h at 70 °C. Then, the solution of citric acid monohydrate C₆H₈O₈ H₂O (99.5%, Sigma-Aldrich) was added as the main chelating agent. Acetic acid (99.5%, Sigma-Aldrich) or ethylene glycol (99%, Sigma-Aldrich) was added as the second chelating agent. The solutions were then mixed and stirred for 3 h at 70 °C. To remove the residual water from the solutions and achieve a transparent gel, the evaporation process was applied. The xerogels (pre-heated powder) were dried in air for 12 h at 150 °C and ground in agate mortar. In the last step, the powders were heated in air from room temperature to 560 °C for 12 h and kept at 560 °C for 5 h. The sample obtained only using citric acid as the main chelating agent was labelled 'VO@1'. The powder synthesized with two chelating agents: citric with Acetic acids and citric acid with ethylene glycol was labelled 'VO@2' and 'VO@3', respectively. Figure 1, shows the schematic representation of the synthesis process used in the present case.Figure 1

Schematic representation of the V₂O₅ nanorods preparation using different chelating agent.

Analytical grade ammonium metavanadate (NH₄VO₃) ≥ 99.0%, cetyl trimethyl ammonium bromide (CTAB) ≥ 98%, sodium hydroxide (NaOH) ≥ 98%, methyl orange (MO) 85%, benzoquinone (BQ) ≥ 98%, triethanolamine (TEA) ≥ 99%, and isopropyl alcohol (IPA) ≥ 99.7% were purchased from Sigma-Aldrich (St. Louis, MO, USA). All other chemicals and reagents were analytical grade and used without further purification. All the required solutions were prepared with distilled water.