Journal of Colloid and Interface Science, Vol.538, 377-386, 2019
Construction of core-shell mesoporous carbon nanofiber@nickel cobaltite nanostructures as highly efficient catalysts towards 4-nitrophenol reduction
We herein report small sized nickel cobaltite (NiCo2O4) nanosheets (103-144 nm x 71-97 nm) firmly coated on mesoporous carbon nanofibers (MCNFs), as active and stable catalysts for degradation of 4-nitrophenol in sewage with NaBH4 as the reductant. MCNFs with surface O-functionalities were first constructed by morphology-conserved transformation of zinc-trimesic acid fibers, which provide scaffolds to anchor trisodium citrate-induced Ni-Co hydroxide nanosheets. Upon calcination, the resultant core-shell MCNF@NiCo2O4 nanostructures were fabricated and characterized by SEM, TEM, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and N-2 adsorption/desorption techniques. The anchored NiCo2O4 nanosheets were dense (75 wt%) but well-dispersed on the surface of MCNF (pore size 4.0 nm), and proved to be highly active and stable towards the reduction of 4-nitrophenol to 4-aminophenol. It showed a large activity factor of 2.53 s(-1) g(-1), exceeding most transition metal oxide catalysts, and MCNF@NiCo2O4 could be cycled at least 20 times without obvious loss of activity. Temperature-programmed desorption and reduction by hydrogen (H-2-TPD and H-2-TPR) studies showed that, the metal oxide dispersion and thereby the amount of H-2 adsorbed were enhanced, and the interfacial interaction was also strengthened. These should be responsible for the excellent activity and stability of MCNF@NiCo2O4 towards 4-nitrophenol reduction. (C) 2018 Elsevier Inc. All rights reserved.