BACKGROUND During recent years, great efforts have been devoted towards the functionalization of metal oxide nanomaterials with various carbonaceous groups to enhance their catalytic performance for environmental remediation applications such as dye degradation. Here, we synthesized Co3O4, Co3O4:NiO and Co3O4:PdO/Pd nanomaterials via organic compounds of Abies pindrow Royle following a hydrothermal route and then investigated them as catalysts for the degradation of methyl orange in aqueous solution in the presence of solar light as well as under dark ambient conditions. RESULTS The chemical composition and phase analysis of Co3O4, Co3O4:NiO and Co3O4:PdO/Pd were confirmed using X-ray diffraction, energy-dispersive X-ray spectroscopy and Raman spectroscopy, while spherical nanostructures were observed using field emission scanning electron microscopy. Carbon- and oxygen-containing functional groups were revealed using Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. The catalytic efficiency of the functionalized nanocatalysts was enhanced to 99% and 98% by incorporation of NiO and PdO/Pd, respectively, within 15 min in the presence of solar light. Whereas, under dark conditions, the degradation efficiency of Co3O4:PdO/Pd and Co3O4:NiO was calculated as 75% and 77%, respectively. The catalysts demonstrated excellent reusability in four cycles of experiments with pseudo-first-order kinetics (R-2 < 1) in the light and under dark conditions. CONCLUSIONS The findings demonstrated an efficient and sustainable bio-templated synthesis of nanocatalysts for removal of organic dyes from aqueous environment. The excellent photocatalytic potential of phytosynthesized Co3O4:PdO/Pd and Co3O4:NiO was attributed to nanostructures as well as to incorporated carbonaceous compounds. (c) 2020 Society of Chemical Industry