Yongfeng Li

Design of three dimensional hybrid Co3O4@NiMoO4 core/shell arrays grown on carbon cloth as high-performance supercapacitors

Electrodes with rationally designed hybrid nanostructure composites can have superior electrochemical performance for supercapacitors to single structured materials. In this work, the uniform three dimensional (3D) hybrid Co3O4@NiMoO4 nanowire/nanosheet arrays directly grown on carbon cloth were designed and synthesized via a two-step hydrothermal method. A series of characterizations of SEM, XRD, XPS, TEM and N2 adsorption/desorption isotherms were used to verify the hierarchical core/shell hybrid nanostructure of as-prepared products, which combines the advantages of the good rate capability of Co3O4 nanowires and the high surface area of NiMoO4 nanosheets. As a binder-free electrode, the fabricated 3D hybrid nanocomposite achieves a high areal capacitance of 3.61 F cm−2 at a current density of 3 mA cm−2 and a capacitance retention of 82% with the increase of current density from 3 to 15 mA cm−2. Besides, the hybrid nanostructured product also exhibits lower bulk resistance and lower charge transfer resistance than single structured Co3O4 material. The outstanding electrochemical behaviour and the facile fabrication process suggest that this hybrid nanoarchitecture material has potential application in high-performance supercapacitors.

Kinetics of methanol steam reforming over COPZr-2 catalyst

Abstract The COPZr-2 catalyst, which was prepared in our prophase research, showed good catalytic performance in methanol steam reforming reaction. In this article, the best one was chosen as an example to study the reaction kinetics of methanol steam reforming over this type of catalyst. First, the effects of methanol conversion to outlet CO 2 and methanol conversion to outlet CO on methanol pseudo contact time W/F MeOH were investigated. Then by applying the reaction route that methanol direct reforming (DR) and methanol decomposition (DE) were carried out in parallel, the reaction kinetic model with power function type was established. And the parameters for the model were estimated using a non-linear regression program which computed weighted least squares of the defined objects function. Finally, the kinetic model passed the correlation test and the F -test.

Effect of textual features and surface properties of activated carbon on the production of hydrogen peroxide from hydroxylamine oxidation

Herein, the textural features and surface properties of activated carbon were mediated by oxidation in the gas-phase or liquid-phase. Activated carbon (AC) treated by gas-phase oxidation showed greatly enhanced production of hydrogen peroxide (H2O2) via hydroxylamine oxidation primarily because of the formation of more surface quinoid species. The yield and selectivity of H2O2 increased to 55% and 87%, respectively, which were much superior to those of the parent AC catalyst. Detailed structural and surface analyses revealed that gas-phase oxidation produced more quinoid but less carboxylic groups on activated carbon, and the opposite effect was observed for the samples treated by liquid-phase oxidation; this confirmed the crucial role of the quinoid groups on AC. Quantitative correlation of the relationship between the activity and the number of the surface quinoid groups further indicated the critical role of the quinoid groups, serving as intrinsic active species.

Shape-controlled synthesis of nickel–cobalt–sulfide with enhanced electrochemical activity

Morphology control of electrode material is critical for high performance supercapacitors. The synthesis of shape-controlled materials is helpful to design advanced electrode materials for supercapacitors. Herein, we prepared two types of NiCo2S4 with nano-bud and nano-mesh morphologies under hydrothermal conditions by facile controlling the reaction time. These materials display morphology-dependent electrochemical activity. Electrochemical measurements showed that the nano-mesh-like NiCo2S4 demonstrate the superior pseudocapacitive performance with a high specific capacitance (3.00xa0Fxa0cm−2 or 1250xa0Fxa0g−1 at 2xa0mAxa0cm−2) and a favorable rate capability (77.8% from 2 to 25xa0mAxa0cm−2). Moreover, the specific capacitance remains 80% of its initial value after 5000 cycles even at high current density of 20xa0mAxa0cm−2. The mesh-like NiCo2S4 also displays a low overpotentials of 299xa0mV at the current density of 30xa0mAxa0cm−2, showing better performance in electrochemical oxygen evolution reaction.

Preparation and Application of Pd-Based Stainless Steel Wire Mesh Monolith Catalyst

The Pd-based oxidation catalysts on stainless steel wire mesh(SSWM) monolith were prepared by electroless plating method. The effect of two different acid bath (including HNO3-HF and concentrated HCl) on the surface morphology of SSWM substrate and the adhesion of palladium particles with substrate were firstly studied. Then the etched SSWM monoliths were used as support to prepare Pd/SSWM monolith catalysts by electroless plating method and their application in toluene catalytic oxidation was also studied. The results indicated that the optimal palladium loading was 0.3wt% and the calcination temperature was 600°C. And the catalyst etched by HNO3-HF showed better activity in toluene catalytic oxidation and worse adhesion of palladium particles with substrate than that etched by concentrated HCl.

Complete Toluene Oxidation over Palladium-Based Monolithic Catalyst Prepared via a New Electroless Plating Method

The palladium-based catalyst of 0.36wt%Pd/cordierite honeycomb ceramics (CHC) without alumina interlayer film was prepared via a new electroless plating method. The results of activity test for complete toluene oxidation showed that the prepared catalysts had good catalytic activity and temperature resistance. The total oxidation temperature (T99) for toluene was at 230°C for the catalyst calcined at 500°C. The scanning electron microscopy (SEM) results indicated that the particles of palladium phases were small and well dispersed on the CHC substrate surface. And the X-ray photoelectron spectrum (XPS) further revealed that both PdO state and adsorbed oxygen species participated and played a more important role in toluene oxidation reaction.

Palladium-Based Catalyst without Interlayer Film Prepared by Electroless Plating for Catalytic Combustion of Toluene

The palladium-based combustion catalysts on cordierite honeycomb ceramics (CHC) substrate without interlayer film (Pd/CHC) were prepared by electroless plating method. By means of scanning electron microscopy (SEM) and BET specific surface area, it was found that the palladium phases on the prepared catalyst after calcination treatment at 500°C were well dispersed on substrate with small and uniform particles. The X-ray diffraction, energy dispersion X-rays (EDX) analysis, adherence test and temperature programmed reduction (H2-TPR) analysis further indicated that the palladium phase had good adherence strength on the surface of CHC substrate and the moderate ratio of metallic Pd and PdO phase was only obtained on the catalyst calcined at 500°C . Moreover, the results of activity tests for toluene combustion showed that the 0.24%Pd/CHC catalyst had good low temperature catalytic activity and temperature-resistance property. The total combustion temperature (T90) for toluene over catalyst calcined at 300, 500 and 900°C was at 239, 225 and 233°C respectively. And the toluene conversion could keep up above 97% during the stability test of Pd/CHC catalyst at 230°C for 105 h, indicating the good catalytic stability of the prepared catalyst.

Study on Removing the Floating Oil on the Surface of Wood Vinegar

Pure wood vinegar is widely used in industry, agriculture and other areas as regulators, but the wood vinegar which produced usually is filled with oil on the surface .The paper mainly study on removing the floating oil on the surface of wood vinegar,choosing the best surfactant called Tween 80 to removing the floating oil and making wood vinegar in a steady system. By this way, it will not appear oil on the surface of wood vinegar for more than half an year, which will broaden the commercial application of wood vinegar

Effect of Electroless Plating Conditions on Toluene Catalytic Combustion Performance of Palladium-Based Catalyst

Catalytic combustion of volatile organic compounds (VOCs) is a high efficient and low-polluted technique. In this paper, the palladium-based combustion catalysts on cordierite honeycomb ceramics (CHC) substrate without interlayer film — Pd/CHC, were prepared by electroless plating method, and the effect of preparing conditions for the catalysts on the catalytic performance of toluene combustion was mainly studied. The optimal conditions were confirmed as follows: plating bath temperature is 60°C, plating time is 30min, palladium salt concentrationis 0.2g/L, and calcination temperature after plating is 500°C. Finally, the stability test further indicated that the Pd/CHC catalyst prepared by the optimal electroless plating conditions has good catalytic stability.

Catalytic Combustion of Toluene on Cu-Mn Complex Oxides Prepared by Urea-Based Hydrothermal Method

Catalytic combustion of toluene on Cu-Mn complex oxides was investigated. The catalysts were prepared by urea-based hydrothermal method and characterized by XRD and SEM. It was found that both the decrease of the Cu/Mn molar ratio and the increase of reaction time contributed to improving catalytic activity for toluene combustion. The temperature for 99% conversion of toluene (T99) was lowered to 210°C. The main crystalline phases of Cu-Mn complex oxides were CuO and Cu0.45Mn0.55O2. It was showed that the existence and high dispersion of Cu-Mn complex oxides were related to the catalytic combustion activity.