Hierarchical polymorphic MnCO₃ series induced by cobalt doping via a one-pot hydrothermal route for CO catalytic oxidation

Abstract

In this study, a series of cobalt-doped MnCO 3 hierarchical microstructures with different morphologies were synthesized by tuning a single variable (the dopant content) via a one-step, mild solvothermal synthesis in a N,N-dimethylformamide (DMF) solution system. Structure evolution of the polymorphic MnCO 3 took place with the morphology obviously transforming from an initial flower-microstructure to fan-like, then to hedgehog-like hemispheres and finally to flake-spheres as the Co 2+ theoretical content (Co/(Co + Mn)) increased from 0 to 20% in the solvothermal process. Cobalt ion modulated reactionlimited aggregation (RLA) is proposed in the growth mechanism. The mechanism of Co 2+ -induced acceleration and full growth is further investigated. The Co 2+ doped manganese carbonate displays wonderful catalytic performance towards CO oxidation. † Electronic supplementary information (ESI) available: The surface areas, compositional data and EDS spectra of Co-doped samples; FTIR spectra of the as prepared doped and undoped MnCO 3 samples; SEM images of the Co-doped P 5 sample obtained at 210 C for different solvothermal times; SEM images of the 5%, 10% Co-doped samples with a prolonged reaction time of 36 h and of the P 5 samples aer repeating the catalysis 6 times; FTIR spectra of the P 5 sample before and aer repeating the catalysis 6 times. See

Study on the morphology-controlled synthesis of MnCO3materials and their enhanced electrochemical performance for lithium ion batteries

“…So far, MnCO 3 materials have been successfully synthesized by precipitation, 12,14 hydrothermal methods, 8,20 ionic liquid-assisted hydrothermal synthesis, 23 chelate mediated growth, 9 and electrodeposition. 18 In order to improve the lithium storage properties, MnCO 3 samples containing hollow microspheres and nanocubes, 14 hierarchically architectured microdumbbells and lamellar-structured nanosheets, 17 mesoporous single crystals, 18 submicron peanuts, 19 ellipsoids and twinborn spheres, 20 flake-spheres 24 and steep rhombohedra microcrystals 25 have been prepared and investigated.…”

ZSM-5 functionalized in situ with manganese ions for the catalytic oxidation of cyclohexane

“…2b-d, the sizes of the Mn-ZSM-5 samples become larger (4-6 mm) with the content of Mn-doping, as a result of the growth acceleration of ZSM-5 via impurities (Mn ions). 41 The compositional data of the as prepared P 0 -P 1 samples are shown in Table 1. As the SiO 2 /Al 2 O 3 ratio increases, the Mn/(Si + Mn) atom ratio increases and the theoretical doping increases, indicating that Mn x+ substitutes Al 3+ into the ZSM-5 lattice and thus drives the formation of a stable MFI structure.…”

Solvothermal synthesis of 1D nanostructured Mn2O3: effect of Ni2+ and Co2+ substitution on the catalytic activity of nanowires

“…The decreased diameters of the Mn 2 O 3 nanowires reveal that the cobalt and nickel ions have played a pivotal role during the growth process of the Mn 2 O 3 . In fact, both Co 2+ (0.072 nm) and Ni 2+ (0.069 nm) ions can accelerate the crystal nucleation rate, 27 leading shorter time for maturity, resulting in the decreased size. Inductively coupled plasma (ICP) analysis indicated that the molar ratio of doping ions in Mn 2 O 3 nanostructures are 1.34% for Ni-doped Mn 2 O 3 , which is lower than theoretical doping and 4.95% for Co-doped Mn 2 O 3 , which is close to the initial reactant composition (Table 1 in ESI †).…”

“…[16][17][18] As is known, the shape-selective synthesis of Mn 2 O 3 nanostructures is demonstrated to be a powerful method to promote their catalytic performance. 27 Generally, surface oxygen vacancies promote high dispersion and strong anchoring of transition metal ions on the metal oxides surface. 19 It is well known that cation substitution can provide an effective tool for tailoring the physicochemical properties of metal oxides, 20,21 in which case the functionalities of Mn 2 O 3 nanomaterials can be optimized by goal-directed control of the cation composition.…”

“…26 We have previously shown that doping of carbonate with cobalt ions can produce enhanced catalytic performance towards CO oxidation. 27 Generally, surface oxygen vacancies promote high dispersion and strong anchoring of transition metal ions on the metal oxides surface. Compared with the three-dimensional (3D) nanostructure, the high aspect ratio of 1D nanowires expose the surface oxygen vacancies on the surface of the nanostructure rather than embedding them in the bulk.…”