间苯二酚二羟乙基醚纯度的差示扫描量热法测定

介绍用差示扫描量热法(DSC)测定结晶物质纯度的原理和实验过程,讨论了Van'tHoff方程和DSC法对间苯二酚二羟乙基醚(HER)样品的适用性,用DSC法测定了不同厂家、不同批次的几种HER产品的纯度。当样品纯度(摩尔分数)高于98.0%时,平行测定结果之差≤0.1%(绝对差),测定结果与高效液相色谱法(HPLC)一致。在测定纯度的同时,测得HER的理论熔点(无限纯样品的熔点)为89.48±0.05℃,熔融热为39.4±0.7J/mol。     

Ultrathin-layered MoS2 hollow nanospheres decorating Ni3S2 nanowires as high effective self-supporting electrode for hydrogen evolution reaction

High-activity and cost-effective transition metal sulfides (TMSs) have attracted tremendous attention as promising catalysts for hydrogen evolution reaction (HER). However, a significant challenge is the simultaneous construction of abundant electrochemical active sites and the fast electronic transmission path to boost a high-efficient HER. Herein, we demonstrate a facile one-step hydrothermal preparation of MoS₂ hollow nanospheres decorating Ni₃S₂ nanowires supported on Ni foam (NF), without any other additional template, surfactant or annealing. In this three-dimensional (3D) heterostructure, the ultrathin-layered MoS₂ hollow nanospheres contribute to the promotion of the total surface area and the electrochemical active sites. Meanwhile, the Ni₃S₂ nanowires are beneficial to the high electrical conductivity. Consequently, the optimized MoS₂/Ni₃S₂/NF-200-24 electrocatalyst presents an extremely superior HER activity to that of individual MoS₂/NF and Ni₃S₂/NF. The HER overpotentials are 85 mV at 10 mA cm⁻² and 189 mV at 100 mA cm⁻², which are also comparable with the state-of-the-art 20% Pt/C/NF electrode at both low and high current.     

Urchin-like Co0.8-Mn0.2-P/CC nanowires array: a high-performance and cost-effective hydrogen evolution electrocatalyst

Using cost-effective materials to replace precious Pt-based hydrogen evolution reaction (HER) catalysts holds great foreground for energy saving and environmental protection. In this work, we successfully prepared an urchin-like Co_0.8-Mn_0.2-P nanowires array supported on carbon cloth (CC) through a hydrothermal-phosphatization strategy and we also systematically studied its electrocatalytic HER performance. Electrochemical tests demonstrate that our urchin-like Co_0.8-Mn_0.2-P/CC possesses outstanding HER activity in acidic and alkaline media. In 0.5 M H₂SO₄, this urchin-like Co_0.8-Mn_0.2-P/CC only requires an overpotential of 55 mV to drive a current density of 10 mA cm⁻², with the Tafel slope of 55.9 mV dec⁻¹. Similarly, when reaching the same current density, just a particularly low overpotential of 61 mV is required with a corresponding Tafel slope of 41.7 mV dec⁻¹ in 1 M KOH. Furthermore, this electrocatalyst exhibits superior stability with 1000 cycles of cyclic voltammetry and 24 h in the I-T test. Such excellent HER catalytic performance can be attributed to the synergistic effect between Co and Mn atoms and high electrochemical active surface area (ECSA). Our work provides a valuable synthesis strategy of non-precious and high HER performance catalytic material.     

Reaction coordinate mapping of hydrogen evolution mechanism on Mg3N2 monolayer

In this work, we have envisaged the hydrogen evolution reaction (HER) mechanism on Mg₃N₂ monolayer based on electronic structure calculations within the framework of density functional theory (DFT) formalism. The semiconducting nature of Mg₃N₂ monolayer motivates us to investigate the HER mechanism on this sheet. We have constructed the reaction coordinate associated with HER mechanism after determining the hydrogen adsorption energy on Mg₃N₂ monolayer, while investigating all possible adsorption sites. After obtaining the adsorption energy, we subsequently obtain the adsorption free energy while adding zero point energy difference (ΔZPE) and entropic contribution (TΔS). We have not only confined our investigations to a single hydrogen, but have thoroughly observed the adsorption phenomena for increasing number of hydrogen atoms on the surface. We have determined the projected density of states (DOS) in order to find the elemental contribution in the valence band and conduction band regime for all the considered cases. We have also compared the work function value among all the cases, which quantifies the amount of energy required for taking an electron out of the surface. The charge transfer mechanism is also being investigated in order to correlate with the HER mechanism with amount of charge transfer. This is the first attempt on this material to the best of our knowledge, where theoretical investigation has been done to mapping the reaction coordinate of HER mechanism with the associated charge transfer process and the work function values, not only for single hydrogen adsorption, but also for increasing number of adsorbed hydrogen.     

Large scale synthesis of Mo2C nanoparticle incorporated carbon nanosheet (Mo2C–C) for enhanced hydrogen evolution reaction

Herein, we report the development of a simple, scalable, and cost-effective strategy for the synthesis of 2D sheets of molybdenum carbide and carbon (Mo₂C–C) nanocomposite, by spray drying, as an efficient electrocatalyst. The synthetic methodology contains spray drying of clear aqueous precursor solution mixture of ammonium carbonate, ammonium heptamolybdate, and glucose followed by calcination under N₂ atmosphere. The desired Mo₂C nanoparticle and carbon were synthesized through carbothermal reduction of spray-dried carbonaceous mass, where partially decomposed glucose serves as carbon source. The synthesized Mo₂C–C sheets calcined at an optimized temperature of 800 °C (Mo₂C–C 800) are thin, porous and contain homogeneously dispersed Mo₂C nanoparticles (8–15 nm) in carbon. The Mo₂C–C 800 modified glassy carbon electrode exhibited excellent electrocatalytic activity for hydrogen evolution reaction (HER) with reduced over-potential of 110 mV at 10 mA/cm² (η₁₀) having reduced Tafel slope 69 mV dec⁻¹ in 0.5 M aqueous H₂SO₄ solution. The catalyst also showed long term stability in an acidic as well as in the red-ox environment.     

Noble metal-free bimetallic NiCo decorated Zn0.5Cd0.5S solid solution for enhanced photocatalytic H2 evolution under visible light

As we know, noble metal (Pt, Pd and Au) with appropriate adsorption free energy of H atoms and higher work function as cocatalyst has been considered to be an effective tactic to enhance photocatalytic activity. However, they are limited severely by scarcity and high-cost. Herein, Zn_0.5Cd_0.5S solid-solution photocatalyst decorated with noble metal-free NiCo cocatalyst has been successfully obtained through one-step photochemical route. It is found that the lifespan of charge carriers of Zn_0.5Cd_0.5S@NiCo can be prolonged dramatically after modification, and the photocatalytic H₂ rate reach to 34.7  mmol g⁻¹·h⁻¹ is nearly 9 times higher than the bare Zn_0.5Cd_0.5S (λ ≥ 420 nm). The superior photocatalytic activity for ZCS@NiCo could be mainly ascribed to higher separation and transfer efficiency of photogenerated carriers by introduced bimetallic NiCo cocatalysts possessing the superior electron transfer property and reducing the onset over-potential of water reduction, which was proved by experiment. This study can provide a potential strategy to design a more efficient noble metal-free cocatalyst over photocatalyst.     

High activity PtPd-WC/C electrocatalyst for hydrogen evolution reaction

Pd modified Pt over a novel support of tungsten carbide nanocrystals (the catalyst denotes as PtPd-WC/C) have been prepared by using an intermittent microwave heating (IMH) method. The as-prepared electrocatalysts are characterized by using the techniques of XRD, SEM, TEM, linear sweeping voltammetry and tested for the hydrogen evolution reaction (HER) in the acidic media. It shows a better performance for the HER on PtPd-WC/C electrocatalyst than that on Pt-WC/C electrocatalyst. In addition, these effects on the catalytic activity by changing environmental temperature and electrolyte concentration were taken into account. Kinetic study shows that the HER on the PtPd-WC/C electrocatalyst gives higher exchange current density in H₂SO₄ solution with high concentration, leading to a lower overpotential and facile kinetics. XRD, SEM and TEM images of PtPd-WC/C show the crystalline features of Pt, Pd and tungsten carbides and indicated the coexistence of these components.     

A novel perspective on designing the inhibitor of HER2 receptor

The hot topic in cancer therapy, human epidermal growth factor receptor 2 protein (HER2), have been indicated that the overexpression of HER2 associated with ovarian, esophageal, gastric and breast cancers recently. To investigate the novel tyrosine kinase inhibitor of HER2 receptor, we employed the molecular simulation and structure-based drug design. Compounds from our laboratory database and two control kinase inhibitors, Tarceva and Iressa, were employed to dock into the HER2 ATP binding site. Three candidates with the highest dockscore were used for De Novo Evolution and 24 virtual compounds were generated. We found that the key residue, Phe731, would construct the pi-stacking interaction with both Tarceva and Iressa was conclusively regarded as the key residue for the inhibitory efficiency. The addition of 1,5-dimethyl-1H-imidazole group on compound A₁ produced the extra hydrophobic interaction, and the pi-stacking interaction with Phe731 was generated by the same aromatic group on both compound A and A₁. Although compound B₁ and C₁ could not produce the pi-stacking interaction with Phe731, both compounds which possessed the lower binding energy and higher dockscore than the two control compounds were believed to compete with the ATP molecule. Compound A₁, B₁ and C₁ were suggested the potent ATP-competitive inhibitors through the significant scores, binding affinity, hydrogen bond linkages and pi-stacking interaction, and these scaffolds were proposed for further drug design.     

Conducting polymer coated carbon surfaces and biosensor applications

This review article focuses on several approaches in the characterization and modification of carbon surfaces with electrocoated thin films which has been realized by recent progress in experimental methods. Electropolymerization and electrocopolymerization of π-conjugated polymers (pyrrole, carbazole, N-vinylcarbazole and aniline) onto carbon surfaces are reviewed with 348 references. Particular emphasis is placed on the recent nanoscale surface characterization techniques applied to the resulting electrocoated polymers onto carbon fibers (i.e., scanning electron microscopy (SEM), cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), focused ion beam-secondary ion mass spectroscopy (FIB-SIMS), Fourier transformed infrared spectroscopy (reflectance-FTIR), and Raman spectroscopic measurements).     

Electrospun fibrous active bimetallic electrocatalyst for hydrogen evolution

Fabricating earth-abundant bifunctional water splitting electrocatalysts with high efficiencies to replace noble metal-based Pt and IrO₂ catalysts is in great demand for the development of clean energy conversion technologies. Molybdenum disulfide (MoS₂) nanostructures have attracted much attention as promising material for hydrogen evolution reaction (HER). The production of hydrogen gas by help of potential efficient earth abundant metal oxides, and stable electrolysis seems a promising for hydrogen evolution reaction pathway in 1 M potassium hydroxide electrolyte media is a hot research topic in the field for clean energy conversion, renewable energies and storage. Here we propose asystem composed NiO nanostructures and MoS₂ deposited on (MoS₂@NiO). Here, by hydrothermal method NiO prepared and MoS₂@NiO by an electrospinning technique complex, can be used as catalyst to produce a large amount of hydrogen gas bubbles. The NiO nanostructures composite having highest synergistic behavior fully and covered by the MoS₂. For the MoS₂@NiO nano composite catalyst, experiment applied in 1 M KOH for the production of hydrogen evolution reaction which exhibits distinct properties from the bulk material. Overpotential values recorded low 406 mV and current density 10 mA cm⁻² measured. Co-catalysts characterized by using different techniques for deep study as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Owing to their unique structure, as-prepared nanocomposite exhibited enhanced catalytic performance for HER due to high electroactive surface area and swift electron transfer kinetics. Based on the HER polarization curves at low potential electrochemical to examine the effects of intercalants HER catalytic efficiency. Our findings establish low Tafel slope (44 mV/decade) and the catalyst stable for at least 13 h. This simple exploitation of MoS₂@NiO composite catalysts depending on the intended application of their electrochemistry.