Probably Zeta potential of Co3O4 or SiC is different in various solvents. I would suggest you to measure the Zeta potential of both the Co3O4 nanoparticle and SiC support in acid, water or ethanol.

Ethanol may 'clean' the surface of one or both to remove 'contaminants' improving otherwise adhesion.

Dear Dr. Lebohang,

1. In the presence of H2O solvent:

The silicon carbide (alpha or beta SiC) is a semiconductor insoluble in water (H2O=polar solvent), in addition, the spinel Co3O4 is insoluble in water (I worked on spinels and I know that Co3O4 is soluble in acids and alkalis), then you probably have obtained a heterogeneous mixture (Co3O4+water+SiC) , therefore after agitation and drying, SiC will bind chemically to Co3O4 by silicon-oxygen bonds (O-Si-O) .

2. In the presence of acid:

The Co3O4 is soluble in inorganic acid. The Co3O4 will bind to SiC probably due to the elevated electronegativity difference between the chemical elements (of Co3O4 and SiC) .

3. In the presence of ethanol solvent:

The ethanol is a polar solvent, the polarized bonds were: C- O and H- O (in the H2O case, H-O are the polarized bonds). We known that , ethanol is a primary alcohol and a weak acid (pKa = 15.5), so the Co3O4 is soluble in this acid.

I think that, the hydrogen atoms of CH3-CH2-OH are capable to form hydrogen bonds with Co3O4 preventing it from binding to SiC surface .