Green synthesis of doped Co₃O₄ nanocatalysts using organic template for fast azo dye degradation from aqueous environment

Abstract

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 Co 3 O 4 , Co 3 O 4 :NiO and Co 3 O 4 :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 Co 3 O 4 , Co 3 O 4 :NiO and Co 3 O 4 :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 Co 3 O 4 :PdO/Pd and Co 3 O 4 :NiO was calculated as 75% and 77%, respectively. The catalysts demonstrated excellent reusability in four cycles of experiments with pseudo-firstorder 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 Co 3 O 4 :PdO/Pd and Co 3 O 4 : NiO was attributed to nanostructures as well as to incorporated carbonaceous compounds.

<p>Bio Framework-Derived Facile MoO3-NiO-PdO-Pd Nanomaterial for Detoxification of Organic Pollutants</p>

“…The present biomimetic synthesis route was designed by modifying reported sol gel methods. [31][32][33][34][35] Aqueous solutions of 40 mM Mo 2 (O 2 CCH 3 ) 4 (3.4 g), 10 mM Ni(CH 3 CO 2 ) 2 •4 H 2 O (2 g) and 10 mM (C 4 H 6 O 4 Pd) (1.8 g) were prepared individually in 200 mL of deionized water. For complete dissolution, each precursor salt was stirred continuously at 550 rpm and room temperature, and then reaction mixtures were mixed together.…”

“…For complete dissolution, each precursor salt was stirred continuously at 550 rpm and room temperature, and then reaction mixtures were mixed together. The foliar bioorganic compounds of A. pindrow were extracted as described earlier, 31 and the prepared extract was utilized for synthesis of MoO 3 -NiO-PdO-Pd nanomaterial. An aliquot of 20 mL of A. pindrow extract was added slowly into prepared mixed solution of precursors on continuous stirring at 80°C for two hours and then retained at room temperature in the dark for 24 h to complete the phytofunctionalization process.…”

“…The calcined nanomaterials of MoO 3 -NiO-PdO-Pd were tested for degradation of MO under ambient conditions (room temperature and air pressure) as well as in the presence of visible light following the methodology adopted to our recent studies. 31 In brief, 100 g of MO was dissolved in 100 mL of deionized water in 1 mg/mL ratio. Two milligrams of the phytosynthesized nanomaterial was treated with 15 mL of prepared MO solution in dark and light conditions for 20 min.…”

“…These identified phytochemicals have huge potential as synthesizing agents for nanomaterial preparation and fabrication. 31 Inspired by previous work, in the present investigation A. pindrow phytochemicals have been explored for the synthesis of MoO 3 -NiO-PdO-Pd ternary metal oxide nanomaterial. The functional groups related to phytochemicals were introduced into the MoO 3 -NiO-PdO-Pd nanomaterial, to remove MO not merely by visible light irritations, but also without light stimulant, under ambient conditions, (without any additional stimulating agent).…”

Semi-conducting Ni/Zn nano-hybrids’ driven efficient electro-catalytic performance: fabrication, characterization, and electrochemical features’ elucidation

“…Nanomaterials synthesized via biogenic route signify a facile, economical, non-toxic, and bio-compatible agents for different applications i.e. electro-catalysts ( 16), supercapacitors (17), antimicrobial agents (18), and photo-catalysts (19) etc.…”