Novel Engineering of Nickel Oxide and Chromium Oxide Nanocomposites for Anti-Corrosion Studies

Mixed nickel oxide/chromium oxide nanocomposites NCs (NiO/Cr2O3 NCs) have been synthesized via two distinct routes, the first: a green direct calcination-microwave-assisted route (sample B1) of nickel and chromium salts in a crucible within an enclosed oven chamber, which provides an environmentally friendly approach free of gaseous and fluid waste. The second is a conventional co-precipitation-microwave-assisted technique (sample B2). Both methods produced a novel bio-inspired hierarchical micro-lobed architecture pattern. The corrosion resistance effects of both samples have been studied. NiO/Cr2O3 NCs were characterized using a field emission scanning electron microscope, X-ray diffractometer, EDX-ray spectroscope, and FT-IR Fourier transform infrared. XRD analysis confirmed average crystallite sizes of 22.93 nm (B1) and 23.24 nm (B2), whereas AFM measurements indicated mean particle sizes of 40–45 nm, suggesting well-defined nanocrystals with minimal agglomeration. Despite significant differences in Ni/Cr composition (B1:∼1.3 vs. B2:∼2.3) from EDS, both (NiO/Cr2O3 NCs) were found to have comparable corrosion inhibition efficiencies of ∼82% when carbon steel was added to (0.1) M of HCl. The assessments of electrochemical analysis identified the primary mechanism as the formation of a protective/shielding layer on the steel surface. These findings indicate that anti-corrosion performance is largely governed by barrier formation rather than stoichiometry, validating both synthesis routes as sustainable strategies for designing high-performance NiO/Cr2O3 NCs as anti-corrosion materials, effectively preventing corrosion.