I'm trying to incorporate metal oxides onto reduced graphene oxide support to be used as a photocatalyst. The pre-synthesized metal oxide was added into the aqueous dispersion of graphene oxide and stirred at room temperature for 10-12 hours to obtain a homogenous solution.. Then the mixture was added into 50 ml teflon lined hydrothermal reactor and heated at 180C for 12 hours. The graphene oxide was successfully reduced into reduced graphene oxide, but when I centrifuge the mixture to remove the solvent, a distinct phases of reduced graphene oxide (top black layer) and metal oxide (yellow layer) was observed. Does that mean that the metal oxide was not chemically bonded onto reduced graphene oxide? I tested the photoactivity of the reduced graphene oxide/metal oxide but the activity was very low as compared to the pure metal oxide. If anyone have experience in working on graphene-based materials, please share your thoughts. Thanks in advance.
I am not an expert on this topic, however, it seems that your metal oxide was not in a homogenous solution as your thought it was. It usually happens because metal oxides, specially iron-based, aggregate in an aqueous environment so I would recommend an ultrasonication of your solution and also check both metal oxide and GO content due to GO shielding effect that can decrease the photocatalytic activity.
I also have a concern about which kind of ''pre-synthesized metal oxide'' is used in this synthesis, do not forget that there are several and different matrices in inorganic oxides compounds with different properties. I would recommend you to perform an XRD analysis in order to check this.
I hope that an expert in this subject helps you to clarify your question,
Regards.
I recommend using ultrasonication for better mixing and dispersion of the particles
We deposit nanoparticles on reduced graphene oxide using a supercritical solvent such as isopropanol. After 24 hours of treatment in a solvent at 250°C, the nanoparticles are completely deposited on the RGO surface.
In your work, you can perform XRD of the washed RGO and understand whether the nanoparticles have settled or not. In addition, transmission electron microscopy will show whether RGO sheets are clean or coated with nanoparticles.
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