Recently, aqueous Zn-ion rechargeable batteries have drawn increasing research attention as an alternative energy storage system relative to the current Li-ion batteries due to their intrinsic properties of high safety, low cost, and high theoretical volumetric capacity. Nevertheless, unwanted dendrite growth on the Zn anode and unstable cathode materials restrict their practical application. In this study, a unique 2D MoS2 coating on a Zn anode using an electrochemical deposition method has been developed for preventing dendrite growth and intricate side reactions. The coated MoS2 layer is a vertically oriented structure that makes the flow of Zn ions easy with a uniform electric field distribution on the anode, resulting in a uniform stripping and plating of Zn2+. In addition, the MoS2 coating enhances anodic diffusion of Zn ions and reduces the series resistance as confirmed by EIS analysis and therefore improves the overall battery performance. The full cell assembled with the MoS2–Zn anode and MnO2 cathode exhibits an excellent reversible specific capacity of 638 mAh/g at 0.1 A/g and stable cycle performance over 2000 cycles with no dendrite formation at the Zn electrode. The presented MoS2 coating on Zn is a facile, scalable, and promising technology for practical Zn-ion batteries with a long life cycle and high safety.

Polyurethane foams are in general flammable and their flammability can be controlled by adding flame-retardant (FR) materials. Reactive FR have the advantage of making strong bond within the polyurethane chains to provide excellent FR over time without compromising physico-mechanical properties. Here, phenyl phosphonic acid and propylene oxide-based reactive FR polyol was synthesized and used along with limonene based polyol for preparation of FR polyurethanes. All the obtained foams showed higher closed cell content (above 96%). By the addition of FR-polyol, the compressive strength of the foams showed 160% increment which could be due to reactive nature of FR-polyol. Moreover, 1.5 wt % of phosphorus (P) content reduced the self-extinguishing time of the foam from 81 (28% weight loss) to 11.2 s (weight loss of 9.8%). Cone test showed 68.6% reduction in peak heat release rate along with 23.4% reduction in thermal heat release. The change in char structure of carbon after burning was analyzed using Raman spectra which, suggests increment in the graphitic phase of the carbon over increased concentration of phosphorus. It can be concluded from this study that phosphorous based polyol could be blended with bio-based polyols to prepare highly FR and superior physico-mechanical rigid polyurethane foams.

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Limonene dimercaptan (LDM), an orange peel oil‐based derivative, and glycerol‐1‐allyl ether (GAE) were used to synthesize bio‐based polyol (LDM‐GAE) using one step photochemical thiol‐ene reaction. The synthesized polyol was used to prepare flame retardant polyurethane foams using dimethyl methyl phosphonate (DMMP) as an additive flame retardant (AFR) and a new bromine containing reactive flame retardant (RFR) derived from 2,4,6‐tribromophenol. Both flame retardants lead to rigid polyurethane foams with excellent physical‐mechanical properties with a short self‐extinguishing time (7.5 and 12.8 sec for DMMP and bromine‐based foams, respectively) and with low weight loss after burning. The reactive bromine polyol lead to rigid polyurethanes with better physical‐mechanical properties than those of foams based on AFR with phosphorous, but the flame retardant properties of foams prepared using AFR are superior to the foams prepared using bromine polyol (RFR). Low addition of DMMP is sufficient to reduce the flammability of polyurethane foam without compromising its physical‐mechanical properties. These flame retardant rigid polyurethane foams based on limonene dimercaptan can be used in all applications of rigid polyurethane foams especially where flammability is an issue such as for insulation of buildings. POLYM. ENG. SCI., 58:2078–2087, 2018. © 2018 Society of Plastics Engineers

Rapidly increasing markets for electric vehicles (EVs), energy storage for backup support systems and high-power portable electronics demand batteries with higher energy densities and longer cycle lives.

Abstract:Hydrogen is an efficient fuel which can be generated via water splitting, however hydrogen evolution occurs at high overpotential, and efficient hydrogen evolution catalysts are desired to replace state-of-the-art catalysts such as platinum. Here, we report an advanced electrocatalyst that has low overpotential, efficient charge transfers kinetics, low Tafel slope and durable. Carbon nanofibers (CNFs), obtained by carbonizing electrospun fibers, were decorated with MoS 2 using a facile hydrothermal method. The imaging of catalyst reveals a flower like morphology that allows for exposure of edge sulfur sites to maximize the HER process. HER activity of MoS 2 decorated over CNFs was compared with MoS 2 without CNFs and with commercial MoS 2 . MoS 2 grown over CNFs and MoS 2 -synthesized produced about 374 and 98 times higher current density at −0.30 V (vs. Reversible Hydrogen Electrode, RHE) compared with the MoS 2 -commercial sample, respectively. MoS 2 -commercial, MoS 2 -synthesized and MoS 2 grown over CNFs showed a Tafel slope of 165, 79 and 60 mV/decade, capacitance of 0.99, 5.87 and 15.66 mF/cm 2 , and turnover frequency of 0.013, 0.025 and 0.54 s −1 , respectively. The enhanced performance of MoS 2 -CNFs is due to large electroactive surface area, more exposure of edge sulfur to the electrolyte, and easy charge transfer from MoS 2 to the electrode through conducting CNFs.

The development of cost-effective, functional materials that can be efficiently used for sustainable energy generation is highly desirable. Herein, a new molecular precursor of bismuth (tris(selenobenzoato)bismuth(III), [Bi(SeOCPh) 3 ]), has been used to prepare selectively Bi or Bi 2 Se 3 nanosheets via a colloidal route by the judicious control of the reaction parameters. The Bi formation mechanism was investigated, and it was observed that the trioctylphosphine (TOP) plays a crucial role in the formation of Bi. Employing the vapor deposition method resulted in the formation of exclusively Bi 2 Se 3 films at different temperatures. The synthesized nanomaterials and films were characterized by p-XRD, TEM, Raman, SEM, EDX, AFM, XPS, and UV–vis spectroscopy. A minimum sheet thickness of 3.6 nm (i.e., a thickness of 8–9 layers) was observed for bismuth, whereas a thickness of 4 nm (i.e., a thickness of 4 layers) was observed for Bi 2 Se 3 nanosheets. XPS showed surface oxidation of both materials and indicated an uncapped surface of Bi, whereas Bi 2 Se 3 had a capping layer of oleylamine, resulting in reduced surface oxidation. The potential of Bi and Bi 2 Se 3 nanosheets was tested for overall water-splitting application. The OER and HER catalytic performances of Bi 2 Se 3 indicate overpotentials of 385 mV at 10 mA cm –2 and 220 mV, with Tafel slopes of 122 and 178 mV dec –1 , respectively. In comparison, Bi showed a much lower OER activity (506 mV at 10 mA cm –2 ) but a slightly better HER (214 mV at 10 mA cm –2 ) performance. Similarly, Bi 2 Se 3 nanosheets were observed to exhibit cathodic photocurrent in photoelectrocatalytic activity, which indicated their p-type behavior.

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