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Cutting fluid in the material processing process is effective in taking away the heat generated to reduce the cutting temperature, as well as reduce friction and wear to improve the surface performance of the material. It is the most basic and necessary component of the material manufacturing industry. However, mineral oil-based cutting fluids and their additives contain some substances that not only jeopardize human health but also pollute the environment, and a great number of researchers are working hand in hand to find green, environmentally friendly alternatives to traditional mineral oil-based cutting fluids. Among them, vegetable oil is a promising and viable alternative, and some safe nanomaterials have been developed as additives to prepare user-friendly and eco-friendly vegetable oil-based nano-cutting fluids. This paper reviews the formulation, characterization, and mechanism of vegetable oil-based cutting fluids and systematically discusses the application of vegetable oil-based nano-cutting fluids in turning, milling, grinding, and drilling. The results of the review show that high-performance vegetable oil-based nano-cutting fluids could be developed to help advance the realization of green manufacturing. Finally, possible directions for future research on plant-based nano-cutting fluids are proposed. [ABSTRACT FROM AUTHOR]

The poor cold flow property is one of the main obstacle factors in affecting the utilization of high proportion biodiesel blends in engines. In this study, methylcyclohexyl methacrylate–methacrylate copolymers (MCHMA-R1MC, R1 = C12, C14, C16, C18) were synthesized at various molar ratios by radical polymerization, and their structures were analyzed and characterized by FTIR, GPC, and 1H NMR. These resulting copolymers were used as the cold flow improvers for biodiesel/diesel blends in terms of cold filter plugging point (CFPP) and solid point (SP) measurement. Results showed that the CFPP and SP of B20 decreased to a varied extent after MCHMA-R1MC treatment. When the monomer ratio of was 1:7, MCHMA-C14MC (1:7) exhibited the greatest reduction on the CFPP and SP of B20 by 18 °C and 25 °C at 2000 ppm dosage. The effects of MCHMA-R1MC copolymers on crystallization behavior and morphology were studied through polarizing optical microscope, differential scanning calorimetry and viscosity–temperature curves. The results indicated that MCHMA-C14MC could effectively delay the aggregation of wax crystals and change their crystalline behavior by changing the crystal shapes and inhibiting the formation of large wax crystals and then lower the low-temperature viscosity of biodiesel blends; therefore, MCHMA-C14MC has proven to be a high-effective cold flow improver for the biodiesel blends. [ABSTRACT FROM AUTHOR]

Platinum group compounds are currently the best performance hydrogen evolution catalysts, but their high price and low abundance limit their large-scale applications. Therefore, noble-metal-free catalysts have become a focus in the research of hydrogen evolution reactions (HER). In this work, we developed a noble-metal-free HER catalyst consisting of Co3O4 supported on N-doped carbon nanotubes (Co3O4-NCTs). The Co3O4-NCT catalyst synthesized by stirring, heating, and high-temperature calcination was studied, showing a very low Tafel plot (32.3 mV dec−1) in an alkaline solution and good stability for hydrogen evolution reactions. In addition, the material synthesis method is simple, the experimental raw materials are cheap and easy to obtain, and it is expected to be suitable for large-scale industrial production. [ABSTRACT FROM AUTHOR]

Herein, a non-polluting and simple electrodeposition strategy is presented by us for fabricating ternary iron cobalt transition metal sulfide (FeCoS) on Ni foam with nanosheet arrays, which are used as cathode materials for asymmetric supercapacitors. The FeCoS-15 nanosheet arrays reveal an admirable specific capacitance of 3741.03 F g−1 when the current density is 1 A g−1 and also exhibit a fantastic cycling performance with 92.84% capacitance retention at 20 A g−1 up to 10,000 cycles. Furthermore, the asymmetric supercapacitors using the FeCoS-15 nanosheet arrays as the positive electrode and the activated carbon (AC) as the negative electrodes demonstrate remarkable electrochemical performance. Our device exhibits an energy density of 54.08 Wh kg−1 with the power density of 800 W kg−1, achieving an impressive cycling retention of 85.64% over 10,000 cycles. The excellent results show that FeCoS nanosheet array materials have a roomy application prospect for high-performance asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

A porous carbon precursor is prepared by modifying polyvinylidene fluoride with nitrogen via a chemical polyreaction and then introducing mesopores using the soft-template method. After carbonization at the appropriate temperature, the obtained carbon material could be applied in supercapacitors without further treatment. The resulting material exhibits not only a comparatively stable nitrogen content that is very close to the nitrogen content of its precursor but also an effective hierarchical porous structure (~ 0.68 and ~ 4 nm). The large specific surface area of the carbon material (up to 1688 m2 g−1) is also an important factor influencing its excellent electrochemical performance. When tested using 6 M KOH as an electrolyte in a three-electrode system, CN-900 exhibits a specific capacitance of 355.6 F g−1 at 1 A g−1. When tested using the same electrolyte in a two-electrode system, CN-900 shows a specific capacitance of 84.08 F g−1 at 0.5 A g−1. In addition, the carbon material can maintain 98.4% capacitance after 8000 charge/discharge cycles at a current density of 2 A g−1. The performance of CN-900 is further tested in a two-electrode solid-state supercapacitor with sulfuric acid/polyvinyl alcohol as the electrolyte, and a specific capacitance of 90.31 F g−1 is observed at 1 A g−1. Therefore, the nitrogen-modified porous carbon is a very promising material with practical applications in supercapacitors. [ABSTRACT FROM AUTHOR]

A series of N/O co-doping porous carbon materials are fabricated from benzotriazole as nitrogen-containing precursor through simple chemical activation (phosphoric acid as activator) and thermolysis process under nitrogen atmosphere. Abundant heteroatoms or functional groups (O: 11.4 at.%; N: 6.5 at.%) in the N/O-3-700 sample can improve the overall electrochemical performance of the material, which is because they can enhance physicochemical properties and induce the pronounced pseudocapacitance. In three-electrode system, the resultant product (N/O-3-700) has a highest specific capacitance value of 357.8 F g−1 at 0.1 A g−1 and good cycle stability (remains more than 94% after 10000 at 1 A g−1), which are attributed to large specific area (1337.7 m2 g−1) and proper functional groups (the sum of N-5 and N-6 content: 42.2 at.%; quinone: 14.3 at.%, C=O and/or COOH: 16.0 at.%). And in symmetric two-electrode cell, the N/O-3-700//N/O-3-700 cell possesses highest energy density of 17.80 Wh kg−1 at 1 A g−1 and still has a high energy density (12.51 Wh kg−1) at 10 A g−1. Thus, the N/O-doped porous carbon can be used for supercapacitors. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen evolution is the most cost-effective method for producing hydrogen as a large-scale clean energy source. Thus, catalysts of low-cost hydrogen evolution are developing at great speed. FeS2-reduced graphene oxide (RGO) hybrid catalysts are synthesized with the use of abundant and inexpensive component worldwide. The catalyst has satisfactory electrocatalytic performance and excellent stability in 0.5 M H2SO4 solution. The catalyst supported by RGO is the ideal electrocatalyst with satisfactory electrical conductivity with 61 mV dec−1 of the Tafel slope. What is more, the current density changes slightly in 36 h and the catalytic performance is relatively stable at 200 mV overpotential. Therefore, the catalyst supported by RGO has high potential for industrial production due to its simple composition and satisfactory electrocatalytic effect. [ABSTRACT FROM AUTHOR]

CoNi2S4/graphene nanocomposites were synthesized by a simple solvothermal method and used as supercapacitor electrodes. CoNi2S4 nanoparticles were doped in graphene layers, which is favorable for improving electrochemical performances of the as-prepared materials. The resulting electrochemical performance of CoNi2S4/graphene nanocomposite electrodes possessed pseudocapacitive behavior with high specific capacitance (1621 F g−1 at 0.5 A g-1), good rate capability (76.7% capacitance retention when reaching 10 A g-1) and outstanding cycling stability (no capacitance loss after 2500 charge-discharge cycles at 5 A g-1). In addition, as the positive electrode of an asymmetric supercapacitor, the material also shows a high specific capacitance of 126.6 F g-1 at 0.5 A g-1, good cycle stability with capacitance retention of 87.4% after 5000 cycles and the highest energy density of 39.56 W h kg-1 at the power density of 374.8 W kg-1. [ABSTRACT FROM AUTHOR]

A facile method for synthesising porous carbon materials with high nitrogen content is employed in this study using 1H-Benzotriazole (BTA) as carbon precursor and ZnCl as active agent at 600-800 °C for 2 h under N atmosphere. Pure BTA completely degrades even at low temperature (270 °C) under inert gas, but ZnCl can convert the more organics to carbon because of its dehydration. The obtained NC-2-700 sample possesses a high specific surface area (1228 m·g) and a nitrogen content up to 10.27 wt%. Moreover, the N-doped carbon exhibits a good electrochemical property (with a specific capacitance of 332 F·g at the current density of 0.5 A·g), as well as an outstanding cycle stability (96.5% of the initial specific capacitance is maintained after 5000 cycles at 1 A·g). In addition, this obtained symmetric ultra-capacitor prepared from the NC-2-700 sample exhibits a highest energy density of 12.94 Wh·kg with a power density of 375 W·kg at a current density of 1 A·g. And even this NC-2-700//NC-2-700 supercapacitor gives 5.43 Wh·kg with a power density of 3750 W·kg at a high current density of 10 A·g. Consequently, these experimental results confirm that the porous carbon materials with high nitrogen content can be a prospective electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

Nitrogen-containing porous carbons with numerous micropores were fabricated by pyrolysing polyvinylidene fluoride (PVDF) membrane following potassium hydroxide (KOH) activation at 600-900 °C for 2 h under N atmosphere. The fabricated nitrogen-containing porous carbons have a large specific surface area of approximately 2289 m g, a certain nitrogen content of 1.35 at.% and a favourable hierarchical porous structure possessing a great number of micropores and a part of mesopores. The carbon materials exhibit high specific capacitance of 338 F g at 0.5 A g in a 6 M KOH and outstanding cycling property of 91.6% maintenance at 2 A g after 10000 cycles. An all-solid-state symmetrical supercapacitor with these as-prepared materials as electrodes can deliver energy densities of 21.9 to 10.4 W h kg at power densities from 700.8 to 12910.3 W kg. To sum up, the as-obtained porous carbon is a type of potential electrode material for electrical double-layer capacitor. [ABSTRACT FROM AUTHOR]

Poly( m-phenylenediamine)-coated hexagonal CoS was firstly synthesized by the polymerization with self-prepared hexagonal Co(OH) used as cobalt source, and the calcination with sulfur powder providing sulfur source. By adjusting the concentration of m-phenylenediamine in the polymerization process, the coating was achieved with the different coated results, further affecting their supercapacitor behaviors by improving diffusion path for fast electron transfer. The resulting CoS/PmPD electrodes demonstrate excellent electrochemical performance with high specific capacitance of 950.1 F g at a current density of 0.5 Å g, good rate performance of 81.1% capacitance retention as the current density grows from 0.5 to 20 Å g, and almost no capacitance loss after 1000 cycles. Moreover, as asymmetric positive electrode material, the CoS/PmPD-1 shows high specific capacitance of 115.3 F g at 0.5 Å g, outstanding rate performance of 78.2% capacitance retention even increased to 20 Å g, superior cycle stability of 87.9% capacitance retention after 5000 cycles at 2 Å g and largest energy density of 36.0 W h kg at power density of 374.67 W kg. This novel CoS/PmPD composite suggests a bright prospect for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Nitrogen-doped porous carbons are attracting considerable attention as adsorbents in CO uptake area or for supercapacitors. In this work, nitrogen-doped porous carbons with a high surface area are efficiently prepared through a facile approach by using polyvinylpyrrolidone as carbon and nitrogen sources through ZnCl activation at 400-700 °C for 4 h under N atmosphere. The obtained nitrogen-doped porous carbons exhibit a narrow microporous structure (0.4-1.0 nm), high specific surface area (up to 1040 m g) and corresponding N content of up to 6.3 wt%. These findings are ascribed to the unique features of high specific surface area and rich N content. Such nitrogen-doped porous carbons show high CO capture of 4.0 mmol g (0 °C) and 2.5 mmol g (25 °C), as well as excellent capacitive performance with a specific capacitance of 292 F g (in 2 M KOH) at a current density of 0.5 A g and cycling stability. A symmetrical supercapacitor based on NPCs shows high energy density (23.2 W h kg at 0.5 A g) and good cycle stability (96.8% capacitance retention after 5000 cycles) in symmetric two-electrode systems. [ABSTRACT FROM AUTHOR]

A facile and cost-efficient synthesis approach toward hierarchically porous cobalt aluminum layered double hydroxide with hydrangea flower-like morphology (PCALs) is developed in this work via the hydrothermal treatment of cobalt- and aluminum-containing precursors under basic conditions following etching with NaOH. The architectures and porosities of the obtained PCALs can be easily modified by the fabrication conditions such as the concentration of the starting materials and the time of etching, which can further influence their electrochemical behavior. As the electrode material in a three-electrode supercapacitor, the PCALs can deliver a high capacitance of 550 F g for 1000 cycles with a retention rate over 82% at 10 A g. In addition, the asymmetric capacitor using PCALs as cathode and active carbon as anode also exhibits an excellent capacitance of 103.5 F g at 0.5 A g, indicating their potentials in the applications of energy storages. [ABSTRACT FROM AUTHOR]