G2 f20 s twin

The morphology and crystal structure of SnO₂/rGO composites were analyzed by scanning electron microscopy (SEM, Hitachi-s4800), transmission electron microscopy (TEM, Tecnai G2 F20 S-Twin). The chemical composite of materials was carried out by energy dispersive spectrometry (EDS, FEI, Quanta FEG 250). The crystal lattice was analyzed by X-ray Diffraction (XRD, Bruker AXS, D8 Advance). The degree of reduction of rGO was characterized by Raman spectroscopy (Raman, Horriba-JY, LABRAM HR).

The phase composition was analyzed by X-ray diffraction (XRD), which was carried out on an X'Pert Pro X-ray diffractometer (PANalytical, the Netherlands) with Cu K alpha radiation at 40 kV and 40 mA. A special container was used to prevent air and water contamination when samples were transferred and scanned. The morphology of samples was studied using scanning electron microscopy (SEM, Hitachi SU-70) and transmission electron microscopy (TEM, Tecnai G2 F20 STWIN) with energy dispersive spectroscopy (EDS). The hydrogen absorption and desorption results were obtained using Sieverts-type apparatus. Approximately 75 mg sample was heated to 430 °C at a heating rate of 2 °C min⁻¹ in a stainless steel container during testing of the non-isothermal hydrogen desorption properties. Isothermal measurements were performed by quickly heating the sample to the target temperature and then keeping the temperature constant throughout the whole test. In addition, the isothermal absorption performance was measured at various temperatures under a hydrogen pressure of 30 bar while the isothermal desorption performance was tested at different temperatures under a hydrogen pressure below 0.01 bar.