The preparation of holey phosphorene by electrochemical assistance

Black phosphorus (BP), an emerging two-dimensional (2D) layered semiconductor material, has been applied to various fields due to its excellent properties such as remarkable in-plane anisotropy, high carrier mobility, and high on-off ratio. It is well known that the properties of BP depend on its structure and morphology, and the nano-BP is usually superior to bulk BP in terms of application and performance. Up to now, the reported nano-BP with different structure and morphology only includes two-dimensional phosphorene and zero-dimensional BP quantum dots. It is very possible to develop nano-BP with a novel structure to improve the performance and expand its application. In this work, a novel phosphorene with a holey structure was prepared by electrochemical assistance for the first time. The obtained holey phosphorene was characterized by TEM, XPS, Raman, XRD, SEM, AFM and UV–Vis techniques. The relevant results indicate that the thickness of the synthesized holey phosphorene was 1–2 nm (ca. 1–2 layers), and the pore size ranges from a few nanometers to tens of nanometers. Keywords: Black phosphorus, Holey phosphorene, Electrochemical assistanc

Interactions of Supercritical CO2 with Coal

Carbon dioxide sequestration on coal with enhanced coalbed methane recovery (CO2-ECBM) is acknowledged as a promising way to mitigate CO2 emissions. For successfully understanding and implementing CO2-ECBM process, the potential interactions of CO2 with coal during CO2 sequestration in coal seams were investigated. Research methods consisting of low-temperature nitrogen adsorption desorption and chromatographic analysis were used to address the transformation of coal pore morphology and the capability of supercritical CO2 extraction when coal contacts with high pressure CO2. According to the test results, interaction of coal with high pressure CO2 does not create a significant influence on pore shape and mesoporous volume distribution of any rank of coal. However, this causes the coal surface fractal dimension and specific surface area to be changed, which implies that the coal's pore morphology change due to CO2 sorption is irreversible. The results also indicate that the injection of high-pressure CO2 does not only change the pore morphology of coal but also has the ability to extract the hydrocarbons present in the coal matrix. The extracted hydrocarbons are of biological toxicity and can be mobilized with gas or water to other geologic structures and aquifers. Thus, the potential environmental safety and health issues (ES&H issues) related to CO2 sequestration in deep coal seams require thorough assessment

Synergistic Effects of Black Phosphorus/Boron Nitride Nanosheets on Enhancing the Flame-Retardant Properties of Waterborne Polyurethane and Its Flame-Retardant Mechanism

We applied black phosphorene (BP) and hexagonal boron nitride (BN) nanosheets as flame retardants to waterborne polyurethane to fabricate a novel black phosphorus/boron nitride/waterborne polyurethane composite material. The results demonstrated that the limiting oxygen index of the flame-retarded waterborne polyurethane composite increased from 21.7% for pure waterborne polyurethane to 33.8%. The peak heat release rate and total heat release of the waterborne polyurethane composite were significantly reduced by 50.94% and 23.92%, respectively, at a flame-retardant content of only 0.4 wt%. The superior refractory performances of waterborne polyurethane composite are attributed to the synergistic effect of BP and BN in the gas phase and condensed phase. This study shows that black phosphorus-based nanocomposites have great potential to improve the fire resistance of polymers

A facile and mild route for the preparation of holey phosphorene by low-temperature electrochemical exfoliation

Holey phosphorene, a novel type of nano-black phosphorus, has been theoretically predicted to have potential for a wide range of applications in catalysis, membrane separation and other fields. However, its practical application is limited by its method of preparation. Up to now, the only reported battery-assisted method for preparing holey phosphorene is complicated, time-consuming and not at all environmentally friendly. Herein, a low-temperature electrochemical exfoliation method which is both environmentally friendly and adaptable is proposed for the preparation of holey phosphorene. More importantly, the pore size of the resulting holey phosphorene can be adjusted, which would be useful in applications including photocatalysis and gas membrane separation. AFM, TEM, Raman and XPS results show that the horizontal size and thickness of the holey phosphorene are 0.3–1.4 μm and 1–2 nm, respectively, while the pore sizes range from several to dozens of nanometers

High specific capacity of TiO(2)-graphene nanocomposite as an anode material for lithium-ion batteries in an enlarged potential window

Abstract not availableDandan Cai, Peichao Lian, Xuefeng Zhu, Shuzhao Liang, Weishen Yang, Haihui Wan

High reversible capacity of SnO2/graphene nanocomposite as an anode material for lithium-ion batteries

A gas-liquid interfacial synthesis approach has been developed to prepare SnO2/graphene nanocomposite. The as-prepared nanocomposite was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller measurements. Field emission scanning electron microscopy and transmission electron microscopy observation revealed the homogeneous distribution of SnO2 nanoparticles (2-6 nm in size) on graphene matrix. The electrochemical performances were evaluated by using coin-type cells versus metallic lithium. The SnO2/graphene nanocomposite prepared by the gas-liquid interface reaction exhibits a high reversible specific capacity of 1304 mAh g(-1) at a current density of 100 mA g(-1) and excellent rate capability, even at a high current density of 1000 mA g(-1), the reversible capacity was still as high as 748 mAh g(-1). The electrochemical test results show that the SnO2/graphene nanocomposite prepared by the gas-liquid interfacial synthesis approach is a promising anode material for lithium-ion batteries. (c) 2011 Elsevier Ltd. All rights reserved

A Novel Application of Phosphorene as a Flame Retardant

Black phosphorene-waterborne polyurethane (BPWPU) composite polymer with 0.2 wt % of black phosphorene was synthesized. Scanning electron microscopy (SEM) was used to observe the morphology of phosphorene in polyurethane matrix, which indicated that the phosphorene distributes uniformly in the PU matrix. The flammability measurements were carried out to investigate the flame-resistant performances of phosphorene, which indicated that phosphorene could effectively restrict the degradation of the PU membrane. Compared by the pure WPU, the limiting oxygen index (LOI) of BPWPU increased by 2.6%, the heat flow determined by thermal analysis significantly decreased by 34.7% moreover, the peak heat release rate (PHRR) decreased by 10.3%

Fabrication and Application of Black Phosphorene/Graphene Composite Material as a Flame Retardant

A simple and novel route is developed for fabricating BP-based composite materials to improve the thermo-stability, flame retardant performances, and mechanical performances of polymers. Black phosphorene (BP) has outstanding flame retardant properties, however, it causes the mechanical degradation of waterborne polyurethane (WPU). In order to solve this problem, the graphene is introduced to fabricate the black phosphorene/graphene (BP/G) composite material by high-pressure nano-homogenizer machine (HNHM). The structure, thermo-stability, flame retardant properties, and mechanical performance of composites are analyzed by a series of tests. The structure characterization results show that the BP/G composite material can distribute uniformly into the WPU. The addition of BP/G significantly improves the residues of WPU in both of TG analysis (5.64%) and cone calorimeter (CC) test (12.50%), which indicate that the BP/G can effectively restrict the degradation of WPU under high temperature. The CC test indicates that BP/G/WPU has a lower peak release rate (PHRR) and total heat release (THR), which decrease by 48.18% and 38.63%, respectively, than that of the pure WPU, respectively. The mechanical analysis presents that the Young’s modulus of the BP/G/WPU has an increase of seven times more than that of the BP/WPU, which indicates that the introduce of graphene can effectively improve the mechanical properties of BP/WPU