Physical Adsorption and Raman Spectra of Hydrazine\nHydrate on the Graphene Surface

In\nexperimental studies, hydrazine hydrate is widely employed as\na reducing agent for the conversion of graphene oxide to graphene.\nHerein, we conducted theoretical calculations using cluster models\nto investigate the adsorption behavior of hydrazine hydrate on the\nsurface of graphene. The calculated adsorption energy reveals that\nhydrazine hydrate can physically bind to the graphene surface. Our\nfindings indicate that two hydrogen bonds stabilize the hydrazine\nhydrate molecule, while its adsorption onto the graphene surface is\nprimarily driven by van der Waals forces. By combining computational\nsimulations and experimental measurements, we thoroughly examined\nthe Raman spectra of both free and adsorbed hydrazine hydrates, which\nenabled us to gain detailed insights into their molecular vibrations.\nNotably, in the Raman spectra of free hydrazine hydrate, a strong\npeak at around 3300 cm<sup>–1</sup> corresponds to the NH<sub>2</sub> vibration. Similarly, peaks near 3300 cm<sup>–1</sup> were observed in the Raman spectra of graphene with adsorbed hydrazine\nhydrate molecules. The results are expected to provide valuable references\nfor future experimental investigations involving hydrazine hydrate.