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A donor–acceptor pair-based redox-active conjugated mesoporous polymer (TPA-BZ) is synthesized herein via tetrakis-(triphenylphosphine)-palladium-catalyzed Sonogashira coupling using triphenylamine (TPA) and a benzaldehyde (BZ) derivative. The polymer exhibits the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) owing to its semi-conductive nature, adequate surface area, and mesoporosity. However, the functionality of the polymer is aggrandized when it is in-situ-modified with just 12.5 wt % cobalt nanoparticles (∼20–70 nm) to afford Co@TPA-BZ. It is observed that there is a reduction in band gap and an increase in surface area with much more refined pores aiding in enhanced electrode–electrolyte interaction. Co@TPA-BZ exhibits the oxygen evolution reaction along with enhanced ORR and HER. The intermolecular orbital interactions and subsequent charge transfer between reaction intermediates and polymers are elucidated by natural bond orbital analysis. Density functional theory computations provide a descriptor for reactions, clearly signifying the role of cobalt nanoparticles in the lowering of overpotentials and increase in the reaction kinetics. [ABSTRACT FROM AUTHOR]

Exfoliated graphite (EG) was synthesized from natural flake graphite by acid treatment followed by microwave irradiation. A maximum expanded volume of 560 mL/g was achieved for this exfoliation of graphite. EG/phenolic resin composite bipolar plates for polymer electrolyte membrane fuel cell were fabricated with a high loading of EG by compression molding. The composites possess low density, high electrical conductivity, high thermal stability, and high compressive strength. The composite bipolar plates were also characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and so on. The composite prepared with 50 wt% of EG has shown the desired properties for bipolar plate as per the US Department of Energy (DOE-2015) targets. As a result, the EG-resin composites can be used as bipolar plates for polymer electrolyte membrane fuel cell applications., INTRODUCTION Polymer electrolyte membrane (PEM) fuel cells are potentially most promising and efficient power sources for transport, stationary, and portable applications owing to their excellent properties such as high efficiency, [...]

The present experimental endeavor aims to develop and study the characteristics of a novel ground tire rubber media (GTRM) through rheological, thermal, and mechanical characterizations. Thermogravimetric analysis reveals the presence of natural and styrene butadiene rubber in ground tire rubber (GTR) and confirms the thermal stability of developed GTRM under the working temperature of the abrasive flow finishing (AFF) process. Investigation reveals that incorporating GTR into media improves AFF performance up to 50 phr, after which it degrades due to poor self-deforming characteristics and abrasive holding capacity at higher GTR fractions. It has also been observed that the percentage of oil and the size of the GTR particles are significant media parameters that govern the GTRM property and thus influence its performance. GTRM with bigger GTR produces deep abrasive cut marks and nonuniform shearing. A comprehensive study reveals that GTRM containing 50 phr GTR (80 mesh), 10% oil, and 60% SiC (220 mesh) results in the highest percentage improvement in surface roughness (% ?Ra) of 44% on flat geometry. The same media, but with coarser SiC (80 mesh), was also used to polish a micro-grooved workpiece. Results show 64% improvement in Ra for the top surface and 58% for the bottom, respectively. Both surfaces still contain a few pits and unevenness; however, the surfaces and top edge of the groove became smooth after AFF. [ABSTRACT FROM AUTHOR]

Copper-based ternary metal oxide (i.e., Cu0.52Al0.01Fe0.47O4) impregnated reduced graphene oxide nanohybrid is verified for microbial and arsenic treatment. Growth inhibition of colonies are observed around 99.99% (E. coli), and 99.83% (S. aureus) at 10–20 μg/mL of hybrid dosage, respectively. The inhibition rates for both the colonies are increased to 99.9998% at 80 μg/mL. TEM images have shown insight of cell-content/lipid leakage behavior after inoculating with the hybrid. The efficient hindrance towards microbial colony growth is attributed to better charge transfer, reactive oxygen species generation, and metal-ion release. Maximum arsenic sorption capacities are observed around 248 and 314 mg/g for As(III), and As(V), respectively (Ci ~ 500 ppm). Surface morphology studies onto arsenic adsorption are reported with atomic force microscope, and FT-IR/Raman analysis. A detailed discussion onto individual spectra of As 3d spectra confirmed the occurrence of redox transformation in arsenic species [As(III)]. The variation in the quantity (at. %) of oxygen functional groups in O1s spectra (i.e., M–O, M-OH, and -OH2) onto the hybrid supported the ligand-exchange behavior. Cyclic voltammetry study in arsenic electrolytes (10 µM – 1 mM) provides the occurrence of various in-situ electrochemical reactions supporting the redox activity. A significant electromagnetic wave absorption characteristics of the present hybrid is proposed with plausible airborne antimicrobial-agent abilities. [ABSTRACT FROM AUTHOR]