Enhanced Performance of Photocatalytic CO2 Reduction Using Cu@Graphene Nanoparticle-Decorated Co3O4 Nanoneedles

A composite photocatalyst comprising cobalt oxide nanoneedles (Co₃O₄-NDs) modified with multilayer graphene-wrapped copper nanoparticles (MLG-CuNPs) was synthesized for efficient photocatalytic CO₂ reduction. The Co₃O₄-NDs and MLG-CuNPs were prepared via hydrothermal method and low-pressure chemical vapor deposition (LPCVD) technique, respectively. The related material characterizations of MLG-Cu/Co₃O₄-NDs are well investigated by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and UV–vis spectroscopy. Photocatalytic carbon dioxide (CO₂) reduction tests revealed that the carbon monoxide (CO) was identified as the primary product, accompanied by a small amount of methane (CH₄). The photocatalysis performance of MLG-Cu/Co₃O₄-NDs exhibited a total yield that was 2.59 and 3.52 times higher than those of MLG-CuNPs and Co₃O₄-NDs, respectively. The superior performance of MLG-Cu/Co₃O₄-NDs is attributed to the synergistic effects of Co₃O₄-NDs and MLG-CuNPs, as well as the LSPR effect of CuNPs. Additionally, the hierarchical heterostructure facilitates efficient electron-hole pair separation, thereby enhancing overall photocatalytic efficiency. This study highlights the potential of combining metal oxides with conductive materials (i. e., graphene and copper) to develop highly active and stable photocatalysts for sustainable CO₂ conversion.