Jipeng Cheng

Preparation of short carbon nanotubes by mechanical ball milling and their hydrogen adsorption behavior

Abstract Short multi-wall carbon nanotubes (MWNTs) with open tips were obtained by mechanical ball milling. The microstructure characteristics of MWNTs before and after ball milling were checked by transmission electron microscopy (TEM). The effect of ball milling on the hydrogen adsorption behavior of the MWNTs was studied. The hydrogen adsorption experiments were carried out at room temperature under a pressure of 8–9 MPa. The hydrogen adsorption capacity of carbon nanotubes milled for 10 h was 0.66 wt%, which was about six times that of MWNTs without milling. For the carbon nanotubes milled with MgO for 1 h, a hydrogen adsorption capacity of 0.69 wt% was obtained. The enhancement of hydrogen adsorption might result from the increase of defects and surface area of the MWNTs caused by ball milling.

Purification of CVD synthesized single-wall carbon nanotubes by different acid oxidation treatments

Different acid oxidation methods were systematically carried out to purify the SWNTs synthesized by CVD. The results show that the best purification process can produce over 98% pure single-wall carbon nanotubes within 2 h. In this process, it is found by Raman characterization that the amount of nanotubes with small diameters do not diminish within 3 h.

Asymmetric electrochemical capacitors with high energy and power density based on graphene/CoAl-LDH and activated carbon electrodes

Asymmetric electrochemical capacitors (ECs) consisting of composites of reduced graphene oxide (RGO) and CoAl layered double hydroxide (LDH) as positive electrode, activated carbon (AC) as negative electrode (RGO/LDH//AC) and 6 M KOH solution as electrolyte were achieved. RGO/LDH was synthesized by a facile solution method in one step under mild conditions. Owing to its wide operating voltage window of 0–1.75 V and the utilization of RGO, the RGO/LDH//AC capacitor exhibited excellent electrochemical properties with a maximum energy density of 35.5 W h kg−1, much higher than those of LDH//AC (25.1 W h kg−1) and AC//AC (6.3 W h kg−1) electrochemical capacitors. Moreover, the devices also showed a high power density of 8.75 kW kg−1 and long cycle life of ∼90% retention after 6000 cycles at the current density of 4 A g−1. Such high-performance asymmetric electrochemical capacitors offer great promise in the application of energy storage systems.

Synthesis of carbon nanotubes filled with Fe3C nanowires by CVD with titanate modified palygorskite as catalyst

Multi-walled carbon nanotubes (MWCNTs) have been successfully synthesized with titanate-modified palygorskite as catalyst and acetylene as carbon source by chemical vapor deposition (CVD) at high temperature. Transmission electron microscopy (TEM) studies showed that there were a lot of carbon nanotubes partially filled with elongated foreign material in their inner cavities. X-ray energy dispersive spectrum (EDS) analyses and selected area electron diffraction (SAED) investigations on the encapsulated material revealed that it was single crystalline iron carbide (Fe3C) derived from ferric precursors in the mineral. The yield of carbon nanotubes was influenced by preparation temperature based on thermal gravimetric analyses (TGA). The relative quantity of Fe3C nanowires was influenced by the temperature and the local structure of nanotubes upon TEM observations. A growth mechanism is also proposed in the paper.

ACEI/ARB therapy for IgA nephropathy: a meta analysis of randomised controlled trials

Background:  Published reports examining the efficacy of RAS blockers: angiotensin converting‐enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB) agents for preserving renal function in IgA nephropathy (IgAN) have yielded conflicting results. To evaluate systematically the effects of ACEI/ARB agents on IgAN, we conducted a meta analysis of published randomised controlled trials (RCTs).

Combination therapy an ACE inhibitor and an angiotensin receptor blocker for IgA nephropathy: a meta-analysis.

Objective:  The pathogenesis of IgA nephropathy (IgAN) is still unknown. Combination therapy with angiotensin‐converting enzyme inhibitors (ACEIs) plus angiotensin receptor blockers (ARBs) might provide more benefits to IgAN patients. We conducted a systematic review to assess the efficacy of combination therapy for IgAN.

Controllable synthesis of novel one-dimensional carbon nanomaterials on an alkali-element-modified Cu catalyst

A series of novel one-dimensional carbon nanomaterials have been synthesized on an alkali-element-modified Cu catalyst, via a simple chemical vapour deposition method. The alkali-element doping of the Cu catalyst plays a key role in the controllable synthesis of carbon nanomaterials, signifying a novel approach to modifying the Cu catalyst. Owing to their unique morphology and fine quality, the synthesized carbon nanomaterials have fascinating potential applications in nanometre-sized electronic devices.

CoOOH ultrafine nanoparticles for supercapacitors

A novel synthetic strategy was developed to synthesize CoOOH ultrafine nanoparticles with a high surface area of 241 m2 g−1, which showed higher specific capacitance than other reported CoOOH powders when used as electrode materials of supercapacitors.

Preparation of CNTs-supported Fe3O4 and Fe3C Nano-particles and the Investigation on their Magnetic Properties

Magnetite (Fe3O4) nanoparticles uniformly loaded on multi-walled carbon nanotubes (MWCNTs) were synthesized by a wet chemistry method, and then carbon coated Fe3C nanoparticles supported by MWCNTs were prepared by heat-treatments subsequently in nitrogen at 600 degC and in acetylene atmosphere at 500 degC. The as-prepared nanoparticles were all single crystals with a size distribution ranging from 10 to 60nm upon TEM and XRD measurements. The magnetic properties of these two kinds of nanoparticles were measured using vibrating sample magnetometer (VSM) at room temperature. The results show that above materials are useful for magnetic materials, and the method to produce magnetic nanoparticles coated with graphite is rather simple

Activated Carbon Modified by CNTs/Ni-Co Oxide as Hybrid Electrode Materials for High Performance Supercapacitors

Hybrid materials of carbon nanotubes (CNTs) coated with nickel-cobalt (Ni-Co) oxide nanoparticles were synthesized using electroless plating. Transmission electron microscopy images showed that Ni-Co oxide nanoparticles were dispersively distributed on the external surface of CNTs. The composites of Ni-Co oxides modified CNTs were used as additives of activated carbon to improve the electrochemical performance of the electrode materials for supercapacitors. The electrochemical properties of the supercapacitors were investigated by galvanostatic charge-discharge, cyclic voltammetry, and alternating current impedance techniques. The maximum specific capacitance reached 215 F g-1, approximately 23% higher than that without addition of the CNT-based composite, while the resistance of the electrode was also reduced by addition of the composite. The results revealed that the supercapacitor had an excellent charge-discharge cycle behavior and electrochemical stability after 1200 continuous cycles. The improved performance of the supercapacitor can be attributed to the modified structure and high electrical conductivity of the electrode materials due to the addition of the hybrid nanocomposite, which is promising for energy storage applications.