Synthesis and Characterization of Nickel–Magnesium Catalyst Supported on Reduced Graphene Oxide

In this study, nickel–magnesium catalyst supported on reduced graphene oxide nanosheets was synthesized. rGO support was characterized by X-ray diffraction (XRD), surface area and porosity, and thermogravimetric analysis, and fourier-transform infrared (FTIR) and Raman spectroscopy to understand its physicochemical properties. The results revealed that the edge-oxidized rGO has high surface area (258.11 m²g⁻¹) with approximately 36 multi graphitic layers where interlayer spacing is 0.336 nm each. High thermal stability of rGO makes it an excellent support to be used for high-temperature catalytic activity. Subsequently, rGO supported catalysts were synthesized via incipient wetness impregnation method. The amount of Ni was fixed at 20 wt% whilst Mg was varied at 0 wt% and 5 wt% relative to rGO content to assess its effect as second metal towards properties of the catalyst. X-ray diffractograms of Ni₂₀/rGO and Ni₂₀Mg₅/rGO demonstrated formation of new peaks due to presence of NiO and NiO–MgO whereas (002) rGO peak at 26.5° does not show obvious changes, concluding the stability of rGO after the impregnation and calcination processes. Upon impregnation, the surface area and porosity of Ni₂₀/rGO is lower than that of rGO due to dispersion of Ni metal on the rGO surface. BET surface area of Ni₂₀Mg₅/rGO catalyst further decreases to 103.95 m²g⁻¹ due to the addition of metal content but its porosity is higher than Ni₂₀/rGO. Hence, it is postulated that Ni and Mg metal form solid solution (NiO–MgO) on rGO nanosheets which has bigger particle size compared to NiO, lowering its penetration into rGO mesopores.