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Gel polymer electrolytes (GPEs) can avoid the electrolyte leakage risk of electrochemical double layer capacitors (EDLCs). But aqueous GPEs often suffer from narrow electrochemical windows. Herein, a series of deep eutectic solvent (DES)-based supramolecular GPEs are firstly developed for carbon-based EDLCs with wide voltage windows. The as-fabricated DES-based GPE shows an ionic conductivity of ~58 mS cm−1, which makes the stable voltage window of a carbon-based EDLC reach 2.4 V. The carbon-based EDLC exhibits a specific capacitance of 32.1 F g−1, an energy density of 24.6 Wh kg−1 and a capacitance retention of ~90% after 15,000 charge-discharge cycles. Moreover, when quinhydrone is added into the DES-based GPE, the specific capacitance and energy density of the corresponding EDLC can be further expanded to 60 F g−1 and 43.6 Wh kg−1, respectively. Therefore, our work may present a universal strategy to prepare novel supramolecular GPEs for high-performance EDLCs with wide voltage windows.

Low temperature and high pressure line pipes are widely used in hydrogen storage, air separation plant, liquefied natural gas (LNG) transportation etc. The material properties of pipes at low temperature are different from those at room temperature. If the medium in the pipe is corrosive, it will cause the pipe wall thickness to decrease. However, the failure pressure of the corroded hydrogen storage pipeline at extremely low temperature is lacking of adequate understanding. In this paper, we provided a novel failure pressure equation of the mild steel line pipe with corrosion defects at extremely low temperature. Firstly, a mechanical model of the line pipe with corrosion defects is established. And then, an analytical solution of the mechanical model is obtained based on elastic theory. Next, a failure pressure equation of the corroded hydrogen storage pipeline at extremely low temperature is developed. In the end, the accuracy of the failure pressure equation is verified by comparing with finite element method (FEM). The results suggest that the calculated value of the failure pressure equation is consistent with that of FEM. This paper provides a theoretical basis for the safety assessment of low temperature hydrogen storage pipeline. The new equation presented in this paper can provide useful guidance for the design of low temperature and high pressure pipelines.

Efficient catalytic electro-oxidation of methanol or urea is critical to the development of fuel cells, which have attracted considerable interest due to their high energy conversion efficiency, ease of operation and low pollutant emission. In this work, nickel cobalt phosphate (NiCoPO) with different Ni/Co ratio are successfully fabricated by co-precipitation method. The electronic states and texture properties of the active Ni(III) species can be regulated by the introduced Co phosphate. The cobalt introduction effectively reduced the onset potential and increased the oxidation current. Compared with nickel phosphate (NiPO), the onset potential of NiCoPO (4:6) and NiCoPO (6:4) decreased by 135 and 132 mV in urea and methanol electro-oxidation process, respectively. The amperometric i-t curves show that the current densities of NiCoPO electrodes are significantly higher than that of NiPO and CoPO. The NiCoPO (4: 6) and (5: 5) exhibits the highest current of urea and methanol oxidation, respectively. This work provides a research reference about the cobalt doping effect for nickel phosphate as catalysts in electro-oxidation reaction.

Mesoporous nickel phosphate nanotube (Meso NiPO NT) and mesoporous nickel phosphate nanosheet (Meso NiPO NS) are developed as catalysts for electrochemical methanol oxidation. Conventional mesoporous nickel phosphate which is composed of stacked nanocrystals (Meso NiPO), microporous VSB-5 and commercial nickel oxide (NiO) are used as control materials. Notably, both Meso NiPO NT (40.83 mA cm−2) and Meso NiPO NS (44.97 mA cm−2) exhibit much higher oxidation current density than VSB-5 (13.41 mA cm−2), Meso NiPO (19.85 mA cm−2) and commercial NiO (0.87 mA cm−2). As for the durability test on these materials modified fluorine-doped tin dioxide transparent conductive glass (FTO) electrodes, Meso NiPO NT displays the most stable performance and still retains 91.3% electrochemical activity, which perhaps benefit from its nanotube structure and large specific surface area (99.6 m2/g). Moreover, Meso NiPO NT has higher activity and more excellent stability than many of the previously reported nickel-based materials, suggesting a potential development for direct methanol fuel cells.

AgPd alloy nanoparticles (NPs) supported on halloysite nanotubes (HNTs) coated polydopamine (PDA) successfully synthesized by one-pot hydrothermal route. XRD, TEM and XPS were employed to verify the alloy structure of the obtained AgPd NPs. The HAADF-STEM result revealed that the thickness of PDA coating was ∼10 nm, which could be formed on the surface of HNTs, and the existence of PDA was beneficial to deposit AgPd alloys with high dispersibility on the surface of HNTs. AgPd/PDA-HNT nanocomposites were effective catalysts for the hydrolysis of ammonia borane at room temperature, and the reaction was completed within 160 s using Ag3Pd2/PDA-HNT as catalysts, with a high total turnover frequency (TOF) value of 90 molH2 molcatalyst−1 min−1 and a low apparent activation energy (Ea) of 22.7 kJ mol−1. After the sixth cycle, Ag3Pd2/PDA-HNT catalyst retained 72% of its initial activity and 100% conversion. The excellent catalytic properties, good durability and reusability, enabled Ag3Pd2/PDA-HNT to be an ideal catalyst in the practical applications.