Study on the Effect of Solvent for Dispersing Precursor in DSA Production for Ammonia Oxidation

Abstract

Objectives : An economical DSA that can be used for a longer period of time and reduce the amount of precious Ru metal required in preparing the electrode was tried to be developed by using an ionic liquid instead of the alcohols as a solvent for electrode catalyst coating when preparing the DSA and comparing the performance. In addition, the possibility of green hydrogen production using ammonia was investigated by examining the possibility of oxidation of non-aqueous ammonia with the fabricated DSA electrode.Methods : 1, 2 and 3 mg/cm2 RuO2 electrodes were prepared using butanol and imidazolium-based ionic liquid (HMIM)HSO4 as a solvent for electrode coating. To optimize conditions, the electrodes prepared using butanol and ionic liquid were compared by evaluating physical and electrochemical properties. SEM-EDS and XRD were used for evaluating physicochemical properties and cyclic voltammetry was used to investigate the possibility of oxidation of non-aqueous ammonia and to compare the electrochemical properties.Results and Discussion : Through SEM-EDS measurement before and after the accelerated life time test, it was confirmed that there was a difference depending on the solvent, but in al electrodes, the cracks on the surface before the accelerated life test was desorbed and coated Ru was desorbed, revealing the matrix of the electrode. XRD analysis showed that crystallinity of the butanol solvent electrode was smaller than that of the ionic solvent electrode. Through an accelerated life test for 1, 2, and 3 mg/cm2 RuO2 electrodes by solvent, 1 mg/cm2 RuO2 produced using an ionic solution was the shortest, ending in 16 hours. The electrode 3 mg/cm2 RuO2 was terminated at 201 h, showing the longest lifetime. Through cyclic voltammetry, all RuO2 electrodes fabricated confirmed the possibility of 7 N non-aqueous ammonia oxidation and the active area of the electrodes fabricated using butanol showed a higher total electrochemical charge than the electrodes fabricated using an ionic solution.Conclusion : As the DSA solvent affects the crystallinity of the electrode, it was shown that it affects the physical life of the electrode through the accelerated life test results. Through cyclic voltammetry, the RuO2 electrode confirmed the possibility of oxidation of 7 N non-aqueous ammonia. Through comparison of ruthenium loading amount, accelerated life test, and electrochemical total charge, it is considered that the most economical electrode is a butanol solvent 2 mg/cm 2 RuO2 electrode.