Catalyst Composition and Content Effects on the Synthesis of Single-Walled Carbon Nanotubes by Arc Discharge

Single-walled carbon nanotubes (SWCNTs) were prepared by a modified arc discharging furnace using Fe-Ni-Mg powders as catalyst at 600∘C. The effects of catalyst composition and content on the production rate and purity of SWCNTs are investigated in this paper. When the Fe-Ni-Mg catalyst composition is 2: 1: 2 wt% and the catalyst content is 5 wt%, the experimental results indicate that the production of SWCNTs is 12 grams per hour, and the purity and diameter of SWCNTs are 70% and 1.22 ∼1.38 nm, respectively. The results indicate that the cooperative function of catalyst composition and content plays an important role in the production of SWCNTs. The aim of this work is to control the production process of SWCNTs efficiently

The competition and equilibrium in power markets under decarbonization and decentralization

Equilibrium analysis has been widely studied as an effective tool to model gaming interactions and predict market results. However, as competition modes are fundamentally changed by the decarbonization and decentralization of power systems, analysis techniques must evolve. This article comprehensively reviews recent developments in modelling methods, practical settings and solution techniques in equilibrium analysis. Firstly, we review equilibrium in the evolving wholesale power markets which feature new entrants, novel trading products and multi-stage clearing. Secondly, the competition modes in the emerging distribution market and distributed resource aggregation are reviewed, and we compare peer-to-peer clearing, cooperative games and Stackelberg games. Furthermore, we summarize the methods to treat various information acquisition degrees, risk preferences and rationalities of market participants. To deal with increasingly complex market settings, this review also covers refined analytical techniques and agent-based models used to compute the equilibrium. Finally, based on this review, this paper summarizes key issues in the gaming and equilibrium analysis in power markets under decarbonization and decentralization

ECS Solid State Lett.

Pd catalysts supported on carbon black and Ti4O7 were prepared and used as electrocatalysts for formic acid electrooxidation. The structure and morphology were characterized by XRD and TEM. CV results show that Pd/Ti4O7 possesses a higher catalytic activity than Pd/C. XPS analyzes suggest that the higher content of metallic Pd caused by Ti4O7 contributes to the better catalytic performance. Based on the good electrocatalytic performance of Pd/Ti4O7, Pd catalyst supported on PDDA-functionalized Ti4O7 was prepared and exhibited a better catalytic activity. The improvement results from the further increase of metallic Pd content due to the presence of PDDA. (C) 2014 The Electrochemical Society. All rights reserved.Pd catalysts supported on carbon black and Ti4O7 were prepared and used as electrocatalysts for formic acid electrooxidation. The structure and morphology were characterized by XRD and TEM. CV results show that Pd/Ti4O7 possesses a higher catalytic activity than Pd/C. XPS analyzes suggest that the higher content of metallic Pd caused by Ti4O7 contributes to the better catalytic performance. Based on the good electrocatalytic performance of Pd/Ti4O7, Pd catalyst supported on PDDA-functionalized Ti4O7 was prepared and exhibited a better catalytic activity. The improvement results from the further increase of metallic Pd content due to the presence of PDDA. (C) 2014 The Electrochemical Society. All rights reserved

Electrocatalysis of titanium suboxide-supported Pt-Tb towards formic acid electrooxidation

The Pt-Tb catalysts supported titanium suboxide (Ti4O7) with different amounts of Tb were synthesized by a simple simultaneous reduction reaction with sodium borohydride in aqueous solution. The structure and morphology of the catalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM), and element valence states were investigated by X-ray photoelectron spectroscopy (XPS). Electrochemical characterization techniques, including cyclic voltammetry (CV), chronoamperometry (CA) and CO stripping were used to analyse the electrochemical performance of these catalysts for formic acid oxidation. The results revealed that the Pt-2.5%Tb/Ti4O7 catalyst has a significantly higher activity than the Pt/Ti4O7 catalyst. According to CO stripping results, the promotive effect of Tb can be explained by a bifunctional mechanism. Additionally, the analysis for XPS spectra indicates that the higher content of metallic Pt caused by the addition of Tb also contributes to the better catalytic activity of Pt-2.5%Tb/Ti4O7. Copyright (c) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Aerobic Oxidation of Benzyl Alcohol over Activated Carbon Supported Manganese and Vanadium Catalysts: Effect of Surface Oxygen-Containing Groups

In this contribution, the selective oxidation of benzyl alcohol using molecular oxygen over supported manganese and vanadium catalysts was investigated. The catalytic activities were significantly improved after pre-oxidizing the activated carbon support materials. Characterizations of nitrogen physisorption, X-ray diffraction, transmission electron microscopy, and X-ray absorption were involved to examine the physicochemical properties of as-prepared catalysts. By ruling out the effects of specific surface area, active site dispersion, valence and local coordination of Mn and V active species, the improved catalytic activity was attributed to the specific variety and increased density of oxygen-containing groups on activated carbon support surfaces, which was further confirmed by cyclic voltammetry measurements and Fourier transform infrared spectroscopy

Epoxidation of styrene with molecular oxygen catalyzed by cobalt(II)-containing molecular sieves

Co-containing molecular sieves, mainly Co-faujasite zeolite and Co-MCM-41, have been studied for the epoxidation of styrene with molecular oxygen. Characterizations with XRD, TEM, laser-Raman. XPS, and H-2-TPR Suggest that the cobalt introduced into MCM-41 by a template-ion exchange method resembles that exchanged in the faujasite zeolite and exists in the single-site Co(II) state, whereas the sample prepared by the impregnation method contains a large proportion of Co3O4. The Co(II) sites located in the molecular sieves catalyze the epoxidation of styrene by oxygen with higher activity than Co3O4 (ca. 2.6 times based on the same cobalt amount). On the other hand, in homogeneous reactions. Co(NO3)(2) and Co(Ac)(2) are almost inactive for the conversion of styrene with oxygen, whereas CoCl2 and Co(acac)(3) show some activity, but the selectivity for epoxide is remarkably lower as compared with the Co(II)-containing molecular sieves. Among various oxidants examined, oxygen is found to be the best one for the epoxidation of styrene over the Co(II)-containing molecular sieve catalysts. The solvent plays an important role in epoxidation, and superior catalytic performances have been obtained with an acylamide such as N,N-dimethylformamide (DMF) as the solvent. The oxygen species with a radical nature generated by the activation of molecular oxygen over the solvent-coordinated Co(II) site has been proposed for the epoxidation reactions. (c) 2004 Elsevier Inc. All rights reserved

Cobalt nanoparticles prepared in faujasite zeolites by borohydride reduction

Metallic cobalt nanoparticles have been prepared in the faujasite zeolite by the reduction of the Co2+-exchanged zeolite with sodium borchydride aqueous solutions. The influences of the temperature used for treating the Co2+-faujasite zeolite before reduction and the concentration of NaBH4 Solution on the degree of reduction and the size of cobalt particles have been investigated. Although the treatment of the Co2+-exchanged faujasite zeolite at a higher temperature before reduction leads to a lower degree of reduction, an appropriate treatment temperature is needed for obtaining cobalt nanoparticles with sizes less than 5 run. Cobalt particles with a maximum size distribution at 1-2 nm, which are probably located inside the supercages of faujasite zeolite, can be obtained by using a higher concentration of NaBH4 aqueous solution (10 M), while lower NaBH4 concentrations lead to the formation of larger cobalt particles (>10 nm) mainly located outside the cages of the zeolite. The smaller cobalt nanoparticles located inside the supercages of faujasite zeolite exhibit higher CO conversions in Fischer-Tropsch synthesis than the larger cobalt particles outside the supercages or the cobalt on the surface of non-porous silica. Unique product distributions are observed in the catalysis over the smaller cobalt nanoparticles in the supercages of faujasite zeolite. (c) 2005 Elsevier Inc. All rights reserved

Numerical Analysis of Dynamic Characteristics of an Asymmetric Tri-Stable Piezoelectric Energy Harvester under Random Vibrations in Building Structures

This study presents a novel design for a tri-stable piezoelectric vibration energy harvester with an asymmetric structure, which is enhanced with an elastic base (TPVEH + EB), meticulously designed to enhance energy extraction from irregular vibrations in architectural structures. The cornerstone of this design is the asymmetric tri-stable piezoelectric cantilever beam, distinctively arranged within a U-shaped block and fortified with an elastic foundation. A carefully positioned spring (kf)-mass (Mf) system between the U-shaped block and the beam’s fixed end significantly boosts the vertical displacement of the beam during oscillations. Utilizing Lagrange’s equations, we formulated a dynamic model for the asymmetric TPVEH + EB, examining the effects of potential well asymmetry, the stiffness of the elastic base and spring-mass system, the mass of the spring-mass system, and the tip magnet mass on the system’s nonlinear dynamic responses. Our results demonstrate that the asymmetric TPVEH + EB significantly enhances energy harvesting from low-amplitude random vibrations (1.5 g), with the output voltage of the asymmetric TPVEH + EB increasing by 30% and the output power by 25%. Extensive numerical and theoretical analyses verify that the asymmetric TPVEH + EB provides a highly efficient solution for scenarios typically hindered by low energy conversion rates. Its reliable performance under varied and unpredictable excitation conditions highlights its excellence in advanced energy harvesting applications. The improvements detailed in this research underscore the potential of the asymmetric TPVEH + EB to boost energy harvesting efficiency, particularly in powering wireless sensor nodes for structural health monitoring in buildings. By overcoming the limitations of traditional harvesters, the asymmetric TPVEH + EB ensures enhanced efficiency and reliability, making it an ideal solution for a wide range of practical applications in diverse environmental conditions within buildings

Analysis of Progressive Collapse Resistance in Precast Concrete Frame with a Novel Connection Method

The configuration of beam–column joints in precast concrete (PC) building structures varies widely, and different connection methods significantly affect the progressive collapse resistance of the structure. This study investigates the progressive collapse resistance of an innovative beam–column connection node frame. Finite element models of four-story, two-span space frame structures made of reinforced concrete (RC) and PC were developed using ANSYS 14.0/LS-DYNA R5.x software, employing nonlinear dynamic and static analysis to examine structural collapse behavior under bottom middle or corner column damage. Numerical results indicate that following the failure of the middle or corner column due to explosion loading, the vertical displacement and collapse rate of the PC structure with the novel connection method are less than those of the RC structure during collapse progression. Furthermore, upon removal of the middle or corner column, the residual load-carrying capacity of the PC structure with the innovative connection increased by 7% and 3.7%, respectively, compared to the RC structure. This suggests that PC structures with this type of connection demonstrate superior performance in resisting progressive collapse, offering valuable insights for future engineering applications

Int. J. Hydrog. Energy

Pt catalysts supported on titanium suboxide (Ti4O7), commercial TiO2 and carbon black were prepared by a borohydride reduction method, respectively, and used as electrocatalysts for direct formic acid fuel cells (DFAFCs). Transmission electron microscopy (TEM) images show that Pt nanoparticles have a poorer dispersion on Ti4O7 compared to that on TiO2 and carbon black due to the hydrophobicity and high density of Ti4O7. Nevertheless, according to cyclic voltammetry (CV) and chronoamperometry (CA) results, it is found that the Pt/Ti4O7 catalyst possesses better catalytic activity and stability. Besides the high electrical conductivity, it is suggested from X-ray photoelectron spectroscopy (XPS) analyses that the higher content of metallic Pt caused by the Ti4O7 support material also contributes to the better catalytic performance of Pt/Ti4O7. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Pt catalysts supported on titanium suboxide (Ti4O7), commercial TiO2 and carbon black were prepared by a borohydride reduction method, respectively, and used as electrocatalysts for direct formic acid fuel cells (DFAFCs). Transmission electron microscopy (TEM) images show that Pt nanoparticles have a poorer dispersion on Ti4O7 compared to that on TiO2 and carbon black due to the hydrophobicity and high density of Ti4O7. Nevertheless, according to cyclic voltammetry (CV) and chronoamperometry (CA) results, it is found that the Pt/Ti4O7 catalyst possesses better catalytic activity and stability. Besides the high electrical conductivity, it is suggested from X-ray photoelectron spectroscopy (XPS) analyses that the higher content of metallic Pt caused by the Ti4O7 support material also contributes to the better catalytic performance of Pt/Ti4O7. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved