Boron nitride-based electrocatalysts for HER,OER, and ORR: A mini-review

A reliable and efficient solution to the current energy crisis and its associated environmental issues is provided by fuel cells, metal–air batteries and overall water splitting. The heart reactions for these technologies are oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Different supporters such as graphene, carbon nanotube, and graphitic carbon nitride have been used to avoid agglomeration of active materials and provide maximum active surface for these reactions. Among all the supporters, boron nitride (BN) gains extensive research attention due to its analogue with graphene and excellent stability with good oxidation and chemical inertness. In this mini-review, the well-known strategies (exfoliation, annealing, and CVD) used in the synthesis of BN with different morphologies for HER, OER and ORR applications have been briefly debated and summarized. The comparative analysis determines that the performance and stability of state-of-the-art electrocatalysts can be further boosted if they are deposited on BN. It is revealed that BN-based catalysts for HER, OER and ORR are rarely studied yet especially with non-noble transition metals, and this research direction should be studied deeply in future for practical applications.     

Interaction of Glycylglycine with Cationic Surfactants—Cetylpyridinium Chloride and Cetylpyridinium Bromide: A Volumetric,Ultrasonic and Conductometric Study

The interactions of glycylglycine (di-peptide of glycine) also known as 2-[(2-aminoacetyl)amino] acetic acid with cationic surfactants cetylpyridinium chloride (CPC) and cetylpyridinium bromide (CPB) as a function of temperature in aqueous medium has been studied by well-know permutation of volumetric, ultrasonic and conductometric techniques. These measurements have been used to evaluate some useful thermodynamic parameters viz. apparent molar volumes, \( \phi_{v} \), partial molar volumes, \( \phi_{v}^{o} \), transfer volumes, \( \phi_{\text{v}}^{0} (tr) \), partial molar expansibility, \( \phi_{E}^{0} \), hydration number, n_H, apparent molal compressibility, \( \phi_{K} \), limiting partial molal adiabatic compressibility, \( \phi_{K}^{0} \). The specific conductivity (κ) was used to calculate the critical micellar concentration (cmc) and other physicochemical parameters of micellization of CPC/CPB with glycylglycine. The critical micelle concentration, cmc and limiting molar conductivity, \( \varLambda_{m}^{o} \) of the two surfactant systems were determined by using the conductivity data at 298.15 K, 303.15 K, 308.15 K and 313.15 K. The acquired data have been discussed as per various interactions taking place in the ternary system of CPC/CPB, glycylglycine and water.     

Prospects of conducting polymer and graphene as counter electrodes in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) garner considerable research interest because of high photo-to-electric conversion efficiencies at low production cost. Platinum has been reported as an efficient metal as a counter electrode (CE) in DSSCs for its outstanding electro catalytic performance. However, the high cost and susceptibility to corrosion of Pt are paving the way for exploring new materials to replace Pt as a counter electrode in DSSCs. Various conducting polymers, graphene and conducting polymer-graphene nanocomposites have been found as counter electrodes in DSSCs with remarkable photovoltaic performances. The urge to produce composites or hybrids with nanomaterials is derived from the improvement of photovoltaic performances. This review will focus on the unique physical and chemical properties of conducting polymers and graphene, their individual photovoltaic performances as counter electrodes in DSSCs, followed by the synergistic effect of conducting polymers and graphene in conducting polymer-graphene nanocomposites as counter electrodes in DSSCs. Finally a brief outlook is provided to improve the photovoltaic performance of DSSCs using conducting polymers and graphene-based counter electrodes.     

Static stress analysis of composite spur gears using 3D-finite element and cyclic symmetric approach

It is more realistic to include the effect of adjacent teeth stiffness while evaluating the root stresses of a gear which is a rotationally periodic structure. This requires very large core and computational time. In the present analysis an attempt has been made to compare the root stresses with and without considering the effects of adjacent gear teeth stiffnesses using the concept of cyclic symmetry. Further, an attempt has been made to study the performance of a composite spur gear using the above approach. It is found that the root structure predicted by the method of cyclic symmetry is less for both isotropic and orthotropic spur gears.     

Enhancement of Al-N co-dopant solubility in ZnO by high temperature thermal annealing

In this paper, we have developed a method to enhance the Al-N co-dopant solubility in bulk ZnO prepared by solid state reaction method. Reactive donor Al and acceptor N were mobilized by annealing the samples at various temperatures from 650 to 850?°C with a step of 50?°C in a programmable furnace. The solubility enhancement argument was verified by the conductivity measurements which showed that the conductivity of annealed films increases as the annealing temperature increases. The activation energy was calculated by the Arrhenius plot and was found to be (0.08?eV) very close to activation energy of shallow acceptor (nitrogen). To further strengthened our argument, we have also performed XRD, FTIR, Raman Spectroscopy and SEM measurements. XRD data suggested that only ZnO phases were present and no evidence for the presence of AlN, Al₂O₃ or Zn₃N₂ phases. We have also observed weakening and peak shifting of (002) with annealing temperature that suggested the incorporation of more acceptor defects in the crystal of ZnO. FTIR results verified the presence of Zn-O bond (437?cm^?1) along with week vibration of Al-N bond at 917?cm^?1. Raman spectroscopy data consists of 2E₂, A₁ (LO) and E_2(high) modes of ZnO but sample annealed at 800?°C has additional nitrogen related mode at 507?cm^?1. SEM images demonstrated the crystalline nature of samples having smooth surface but sample annealed at 800?°C has rough surface which indicated the enhancement of acceptor defects density.     

Thermal evaporation and condensation synthesis of metallic Zn layered polyhedral microparticles

Metallic zinc layered polyhedral microparticles have been fabricated by thermal evaporation and condensation technique using zinc as precursor at 750 °C for 120 min and NH₃ as a carrier gas. The zinc polyhedral microparticles with oblate spherical shape are observed to be 2-9 μm in diameter along major axes and 1-7 μm in thickness along minor axes. The structural, compositional and morphological characterizations were performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). A vapour-solid (VS) mechanism based growth model has been proposed for the formation of Zn microparticles. Room temperature photoluminescence (PL) emission spectrum of the product exhibited a strong emission band at 369 nm attributed to the radiative recombination of electrons in the s, p conduction band near Fermi surface and the holes in the d bands generated by the optical excitation.     

Does Television Viewing Cultivate Unrealistic Expectations About Marriage?

One explanation for the high divorce rate in our society focuses on the idealistic expectations with which many people enter into marriage. The media have been cited as the source of or major contributor to these expectations; however, no empirical evidence exists to support that claim. Based on a survey of 285 never-married university students, this study sought to examine the relationship between television viewing, holding idealistic expectations about marriage, and intentions to marry. Results from regression and path analyses indicate that, although overall television viewing has a negative association with idealistic marriage expectations, viewing of romantic genre programming (e.g., romantic comedies, soap operas) was positively associated with idealistic expectations about marriage. Further, a strong and positive association between these expectations and marital intentions was evidenced. These findings are discussed in terms of both cultivation theory and the uses and gratifications perspective of media influence.     

Compressive strength-color change relation in mortars at high temperature

Changes in materials' physical, chemical and mechanical properties have to be known to decide whether the buildings exposed to high-temperature effect will be repaired or demolished. In order to carry out the effects of fire and extinguishing on the properties of concrete, mortars with and without silica fume were exposed to different temperatures, such as 100, 200, 300, 600, 900 and 1200 °C, and cooled slowly in the air and fast in water in two groups. Flexural and compressive-strength tests were performed on the samples which were cooled up to room temperature and changes in color were determined by using the Munsell Color System. High temperature has caused damages in mechanical properties of mortars with or without silica fume, especially samples which were cooled in water, which showed significant decrease in mechanical strengths at 600 °C. In this study, it was observed that the changes in color's hue component and the compressive strength have similarities. Test results show that residual color changes in mortar can give an idea about the effect of high temperatures on the mechanical properties of mortar during a fire.     

Improved SPC chart pattern recognition using statistical features

Increasingly rapid changes and highly precise manufacturing environments require timely monitoring and intervention when deemed necessary. Traditional Statistical Process Control (SPC) charting, a popular monitoring and diagnosis tool, is being improved to be more sensitive to small changes and to include more intelligence to handle dynamic process information. Artificial neural network-based SPC chart pattern recognition schemes have been introduced by several researchers. These schemes need further improvement in terms of generalization and recognition performance. One possible approach is through improvement in data representation using features extracted from raw data. Most of the previous work in intelligent SPC used raw data as input vector representation. The literature reports limited work dealing with features, but it lacks extensive comparative studies to assess the relative performance between the two approaches. The objective of this study was to evaluate the relative performance of a feature-based SPC recognizer compared with the raw data-based recognizer. Extensive simulations were conducted using synthetic data sets. The study focused on recognition of six commonly researched SPC patterns plotted on the Shewhart X-bar chart. The ANN-based SPC pattern recognizer trained using the six selected statistical features resulted in significantly better performance and generalization compared with the raw data-based recognizer. Findings from this study can be used as guidelines in developing better SPC recognition systems.