Hydrazine monohydrate

MoS₂ powder was purchased from Sigma-Aldrich (Merck, Darmstadt, Germany). NMP, N,N-dimethylformamide, hydrochloric acid (HCl), dimethyl sulfoxide, and ethanol were purchased from Samchun Chemical, Inc (Seoul, Republic of Korea). Isopropyl alcohol and hydrazine monohydrate were purchased from JUNSEI (Tokyo, Japan). All chemicals were used without further purification.

Hydrazine monohydrate (Junsei, Tokyo, Japan, 98.0%), nitric acid (EMSure, Darmstadt, Germany, 65.0%) and copper (I) chloride (SIGMA-ALDRICH, St. Louis, MO, USA, 97.0%) were used to prepare N₂H₄–Cu⁺–HNO₃ solution in this study. The conditions of each sample is listed in Table 4. All the solutions contain 50.0 mM of N₂H₄. In order to investigate the effects of Cu⁺ ions on N₂H₄ decomposition, the solutions were prepared according to the presence of 0.5 mM of copper ions. Each sample was adjusted to pH 3 by adding nitric acid. To analyze the effects of HNO₃ on N₂H₄ decomposition, each solution was adjusted to pH 1, 3, and 5 by adding 144.7 mM, 50.8 mM, and 49.9 mM of nitric acid, respectively. All the sample solutions included 0.5 mM of copper ions. The 30 mL of sample solutions were stored in the 50 mL vials. After storing the solution in the vial, the nitrogen purging was conducted for 10 min. during the γ-ray irradiation.