Ternary Co3O4-Ni(OH)2-graphene hybrid nanocomposites (NCs) can be fabricated using a facile, room-temperature kinetic spray process in a single step. The fabricated heterostructure electrodes are optimized to enhance the oxygen evolution reaction (OER) in 1.0 M KOH. The deposited films exhibit a mixture of nanosheet and nanoflake morphologies. Raman spectra reveal improvements in various disorder-related modes in the hybrid NCs due to the nanometer scale and the transformation of graphite-stacked layers into thin graphene nanosheets. X-ray photoelectron spectra indicate that strong synergy improvements in the heterostructure NCs are associated with a downshift of the active state’s binding energies. Optimal Co3O4-Ni(OH)2-graphene hybrid ternary NCs exhibit the smallest OER overpotential of 262 mV @10 mA·cm⁻², the lowest Tafel slope of 32 mV·dec⁻¹, and long-term stability of 25 h at a polarization current of 50 mA·cm⁻².
