RESUMO
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.
RESUMO
Black phosphorus quantum dots (BPQDs), a type of nanoscale black phosphorus (BP), have fantastic application prospects in various fields. However, the premise of the application of BPQDs depends on its effective preparation. At present, most of preparation processes of BPQDs involve in organic solvents which may be harmful to humans and the environment. Furthermore, some chemical impurities may inevitably be introduced into the final product. In addition, all the preparation processes need to be carried out under an inert gas due to the instability of BPQDs, which makes the reaction conditions more harsh and complicated. Therefore, an efficient and simple method for the preparation of BPQDs by gas exfoliation with the assistance of liquid N2 (l-N2) was developed for the first time in this study. This method is environmentally friendly and impurity-free because l-N2 is a nontoxic liquid that can be gasified to form N2. The obtained BPQDs were characterized by XRD, Raman, SEM, TEM and UV-Vis techniques and they had a lateral size of 9±3 nm.
RESUMO
Li metal batteries (LMBs) are known as the ideal energy storage candidates for the future rechargeable batteries due to the high energy density. However, uncontrolled Li dendrites growing during charge/discharge process causes extremely low coulombic efficiency and short lifespan. In this work, a thin lithiophilic layer of Ag was coated on the bare Li surface via a thermal evaporation method, which alleviated volume variations and suppressed Li dendrites growth during cycling. As a result, a long lifespan of 250 h at a current density of 1 mA cm-2 was achieved in the symmetric cell when using the Ag-modified Li foil (Ag@Li). The LiFePO4|Li full cell demonstrated an excellent cycling performance with a high specific capacity of 131 mAh g-1 even after 300 cycles at 0.5 C. This study offers a suitable method for stabilizing Li metal anodes in LMBs.
RESUMO
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.
RESUMO
As emerging non-metallic semiconductors, black phosphorus (BP) and few-layered BP (phosphorene) have exhibited unique physicochemical properties and promising application prospect for catalysis related fields. In this review, we first introduced the intriguing properties of BP, including high carrier mobility, a wide optical absorption range and tunable direct band gap. We then summarized the recent research progress about the applications of BP as catalysts, mainly focus on photocatalytic water splitting, photocatalytic degradation of organic pollutants and electrocatalytic H2 and O2 evolution. The recent works about other catalytic applications were also introduced.
RESUMO
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%.
