Mingjun Jia

Complete oxidation of formaldehyde at ambient temperature over supported Pt/Fe2O3 catalysts prepared by colloid-deposition method

The catalytic properties of iron oxide supported platinum catalysts (Pt/Fe(2)O(3)), prepared by a colloid deposition route, were investigated for the complete oxidation of formaldehyde. It is found that all the Pt/Fe(2)O(3) catalysts calcined at different temperatures (200-500°C) were active for the oxidation of formaldehyde. Among them, the catalysts calcined at lower temperatures (i.e., 200 and 300°C) exhibited relatively high catalytic activity and stability, which could completely oxidize HCHO even at room temperature. Based on a variety of physical-chemical characterization results, it is proposed that the presence of suitable interaction between Pt particles and iron oxide supports, which is mainly in the form of Pt-O-Fe bonds, should play a positive role in determining the catalytic activity and stability of the supported Pt/Fe(2)O(3) catalysts.

Oxodiperoxo molybdenum modified mesoporous MCM-41 materials for the catalytic epoxidation of cycloocteneElectronic supplementary information (ESI) available: experimental data. See http://www.rsc.org/suppdata/cc/b2/b207645d/

A hybrid heterogeneous catalyst system, which has been synthesized by covalently anchoring oxodiperoxo molybdenum chelate complexes onto the surface of mesoporous MCM-41, is highly active and truly heterogeneous for the liquid-phase epoxidation of cyclooctene with tBuOOH as the oxygen source.

Simple hydrothermal synthesis of mesoporous spinel NiCo2O4 nanoparticles and their catalytic behavior in CH3OH electro-oxidation and H2O2 electro-reduction

Mesoporous spinel NiCo2O4 nanoparticles were synthesized via a simple hydrothermal strategy. Their physicochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectra (SEM-EDS), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperomerty (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit a particle size of about 200 nm, a specific surface area (SSA) of 88.94 m2 g−1 and a mesopore volume of 0.195 cm3 g−1. The binary electroactive sites of Co and Ni species, high electron conductivity and intriguing mesoporous structures of the NiCo2O4 electrode favor its desirable electro-catalytic activity. A current density of 93 mA cm−2 at 0.6 V in 1 M KOH and 0.5 M CH3OH electrolytes was obtained for CH3OH electro-oxidation, and a current density of 130 mA cm−2 at −0.3 V in 3 M NaOH and 0.5 M H2O2 electrolytes was achieved for H2O2 electro-reduction. Moreover, the NiCo2O4 electrode exhibits a high stability for both catalytic reactions, showing the potential for further development of high performance non-Pt catalysts based alkaline fuel cells (AFCs).

Graphite oxide-supported CaO catalysts for transesterification of soybean oil with methanol.

Graphite oxide (GO) supported CaO catalysts were prepared and successfully applied to the transesterification of soybean oil with methanol. The supports and resultant catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption, thermogravimetry (TG), X-ray photoelectron spectroscopy (XPS), temperature-programed desorption (TPD) and Fourier-transform infrared spectroscopy (FT-IR). The GO supported CaO catalysts exhibited excellent catalytic activity and were easily regenerated by simple heat-treatment. The oxygen-containing groups (i.e., hydroxyl, epoxide groups and carboxyl groups) present on the surface of GO likely act as anchoring centers for CaO. This work demonstrates that graphite oxide is an effective host material of catalytically active CaO nanoparticles for the transesterification of soybean oil with methanol to produce biodiesel.

Adsorption behaviors of methyl orange dye on nitrogen-doped mesoporous carbon materials

A series of nitrogen-doped mesoporous carbon materials (NMC) with different nitrogen contents (from 9.1 to 11.3 wt.%) were prepared using urea and ammonia as economical nitrogen resources by sol-gel method. The NMC materials possessed high surface areas (from 659 m(2)/g to 912 m(2)/g) as well as large number of oxygen-containing and nitrogen-containing groups. The adsorption behaviors of NMC materials for anionic dye methyl orange (MO) were investigated, which are fit excellent for the Langmuir isothermal adsorption equation. All the materials exhibited high adsorption capacity for MO at room temperature. Their adsorption capacity can be adjusted by changing the nitrogen contents in NMC materials. Moreover, treating the NMC material at higher temperature can significantly improve the adsorption capacity for MO. According to the results of characterization, the main features of NMC materials, like large pore size and abundant basic nitrogen-containing groups on the surface, should be related to the excellent adsorption property for MO.

The enhanced catalytic activity and stability of oxodiperoxomolybdenum-modified mesoporous organosilicas in selective epoxidation reactions

Complexes of the type (L–L)MoO(O2)2 heterogenized on phenylene-bridged mesoporous organosilicas show a 10-fold increase in catalytic activity and a high stability in liquid phase epoxidation reactions, with H2O2 as the oxidant, compared to the corresponding MCM-41-derived systems.

Correlation between the microstructures of graphite oxides and their catalytic behaviors in air oxidation of benzyl alcohol.

A series of graphite oxide (GO) materials were obtained by thermal treatment of oxidized natural graphite powder at different temperatures (from 100 to 200 °C). The microstructure evolution (i.e., layer structure and surface functional groups) of the graphite oxide during the heating process is studied by various characterization means, including XRD, N2 adsorption, TG-DTA, in situ DRIFT, XPS, Raman, TEM and Boehm titration. The characterization results show that the structures of GO materials change gradually from multilayer sheets to a transparent ultrathin 2D structure of the carbon sheets. The concentration of surface COH and HOCO groups decrease significantly upon treating temperature increasing. Benzyl alcohol oxidation with air as oxidant source was carried out to detect the catalytic behaviors of different GO materials. The activities of GO materials decrease with the increase of treating temperatures. It shows that the structure properties, including ultrathin sheets and high specific surface area, are not crucial factors affecting the catalytic activity. The type and amount of surface oxygen-containing functional groups of GO materials tightly correlates with the catalytic performance. Carboxylic groups on the surface of GO should act as oxidative sites for benzyl alcohol and the reduced form could be reoxidized by molecular oxygen.

Covalent Immobilization of Imidazolium Cations Inside a Silica Support: Palladium-Catalyzed Olefin Hydrogenation

Mesoporous organosilica materials with different contents of bistrialkoxysilyl imidazolium salts in the framework were synthesized by a one‐step synthesis. Textural characterization of the materials confirmed that the morphology and surface properties of the imidazolium‐bridged organosilicas depended critically on the amount of organic groups in the framework, whereas solid‐state NMR characterization showed that the imidazolium fragments were integrated covalently into the framework. Further reaction of these materials with Pd(OAc)2, followed by reduction with NaBH4 yielded palladium nanoparticles stabilized in the mesoporous organosilicas. The stabilizing effect of the imidazolium cations and the mesostructure contributed to the high activity, selectivity, and stability of the palladium nanoparticles and allowed olefin hydrogenation under mild reaction conditions.

A facile hard-templating synthesis of mesoporous spinel CoFe2O4 nanostructures as promising electrocatalysts for the H2O2 reduction reaction

Mesoporous spinel cobalt ferrite (CoFe2O4) nanostructures were synthesized via a facile Al2O3-assisted hard-templating (HT) strategy. Their physicochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectra (SEM-EDS), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances towards H2O2 reduction reaction (HRR) were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained CoFe2O4 materials exhibit a superior mesoporous nanostructure with a particle size of around 20 nm, a specific surface area (SSA) of 140.6 m2 g−1 and a mesopore volume of 0.2410 cm3 g−1, which favor their desirable electrocatalytic activity. A current density of 123 mA cm−2 at −0.39 V (vs. Hg/HgO) in 3 M NaOH and 0.5 M H2O2 electrolytes was delivered for HRR. Moreover, the CoFe2O4 electrode exhibits a good stability for the catalytic reaction, showing the promising applications for H2O2-based alkaline fuel cells (AFCs).

Oxalate-extended Cd2+–acylhydrazidate coordination polymers: synthesis, structure and fluorescence property

Two new oxalate-propagated Cd2+–acylhydrazidate coordination polymers [Cd2(ox)0.5(Hpth)(pth)(bpy)2] (ox = oxalate, pth = phthalhydrazidate, bpy = 2,2′-bypyridine) 1 and [Cd2(ox)(pdh)2]·H2O (pdh = pyridine-2,3-dicarboxylhydrazidate) 2 were obtained by simple hydrothermal self-assemblies of Cd(CH3COO)2, aromatic dicarboxylic acids, N2H4, and oxalic acid with or without bpy. The acylhydrazidate molecules (pth, pdh) originated from the acylation of N2H4 with aromatic dicarboxylic acids. X-ray analysis revealed that in both compounds, ox acts as the second linker, extending the metal–acylhydrazidate oligomers (tetranuclear for 1; dinuclear for 2) into the high-dimensional coordination polymers. In compound 1, the monoacylhydrazidate molecule with a −2 oxidation state was observed for the first time. In the solid state, only compound 2 emits light, while in an aqueous solution, both compounds emit light. The density functional theory (DFT) calculations indicate that whether in the solid state or in an aqueous solution, the emissions for compound 2 are both assigned to the charge transfer within the pdh molecule, corresponding to the charge transfer from the π* orbitals of the pyridine ring moiety to the π orbitals of the acylhydrazidate ring moiety. The solvent effect of water causes the blue shift from 525 nm to 405 nm. The blue-light emission (465 nm) for compound 1 in an aqueous solution is assigned to the charge transfer between the pth molecules, corresponding to the charge transfer from the π* orbitals of the benzene ring moiety of one pth molecule to the π orbitals of the acylhydrazidate ring moiety of another pth molecule. The Cd2+ center provides the path for charge transfer.