In recent decades, fuel cell technology has been undergoing revolutionary developments, with fundamental progress being the replacement of electrolyte solutions with polymer electrolytes, making the device more compact in size and higher in power density. Nowadays, acidic polymer electrolytes, typically Nafion, are widely used. Despite great success, fuel cells based on acidic polyelectrolyte still depend heavily on noble metal catalysts, predominantly platinum (Pt), thus increasing the cost and hampering the widespread application of fuel cells. Here, we report a type of polymer electrolyte fuel cells (PEFC) employing a hydroxide ion-conductive polymer, quaternary ammonium polysulphone, as alkaline electrolyte and nonprecious metals, chromium-decorated nickel and silver, as the catalyst for the negative and positive electrodes, respectively. In addition to the development of a high-performance alkaline polymer electrolyte particularly suitable for fuel cells, key progress has been achieved in catalyst tailoring: The surface electronic structure of nickel has been tuned to suppress selectively the surface oxidative passivation with retained activity toward hydrogen oxidation. This report of a H2–O2 PEFC completely free from noble metal catalysts in both the positive and negative electrodes represents an important advancement in the research and development of fuel cells.

Alkaline Polymer Electrolyte Fuel Cells Completely Free From Noble Metal Catalysts

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Recent years have witnessed a resurgence of novel, efficient and practical protocols for radical-mediated cross-coupling reactions involving N-(acyloxy)phthalimides (NHPI esters) as redox-active esters. After the initial discovery of the redox-active properties of NHPI esters, exciting examples of SET-based cross-coupling reactions under thermal or photolytic conditions leading to diverse C–X (X=C, B, Si, Se, S) bonds have been published. The operational simplicity and broad applicability exhibited in redox-active NHPI ester-based cross-couplings bode well for their widespread adoption. The review presented herein covers all the recent developments in the field of redox-active ester (RAE)-based cross-couplings since the initial discovery. Depending on the conditions employed the reactions have been categorized into photoinduced and non-photoinduced cross-couplings with representative examples and insightful mechanistic discussions.

N-(Acyloxy)phthalimides as Redox-Active Esters in Cross-Coupling Reactions

The fields of C-H functionalization and photoredox catalysis have garnered enormous interest and utility in the past several decades. Many different scientific disciplines have relied on C-H functionalization and photoredox strategies including natural product synthesis, drug discovery, radiolabeling, bioconjugation, materials, and fine chemical synthesis. In this Review, we highlight the use of photoredox catalysis in C-H functionalization reactions. We separate the review into inorganic/organometallic photoredox catalysts and organic-based photoredox catalytic systems. Further subdivision by reaction class-either sp2 or sp3 C-H functionalization-lends perspective and tactical strategies for use of these methods in synthetic applications.

Photoredox-Catalyzed C-H Functionalization Reactions.

Cation exchange membranes (CEMs) have attracted tremendous attention in electrochemical energy conversion and storage systems owing to their high proton conductivity and chemical stability. However, applications of CEMs suffer from a number of disadvantages such as requirement of costly platinum catalyst, and high crossover of fuels or positively charged redox species due to the electro-osmotic drag. Anion exchange membranes (AEMs) have shown promising characteristics to overcome some of the problems associated with CEMs; the advantages of AEMs being selective transport anionic charge carriers, lower crossover of cationic redox couples, and facile reaction kinetics in energy conversion processes. These unique properties of AEMs result mainly from the density and distribution of positively charged functional groups, along with a macromolecular polymer backbone. As a result, there has been an increasing demand for the development of AEMs with better selectivity, higher chemical stability and conductivity, and a lot of work has been carried out in this area. The aim of this review is to discuss developments in the synthesis and applications of AEMs in the field of electrochemical energy conversion and storage, on which many researchers have been working in recent years.

A review on recent developments of anion exchange membranes for fuel cells and redox flow batteries

A photoinduced cross-dehydrogenative-coupling (CDC) reaction between aldehydes and N-hydroxyimides has been developed for the synthesis of ester derivatives. Using 2 mol% [Ru(bpy)3]Cl2 in dry acetonitrile at room temperature with an LED light bulb, we were able to synthesize N-hydroxyesters in good yields. The ester derivatives are very useful synthetic intermediates, which were transformed to amide and oxazole building blocks in excellent yields.

Cross dehydrogenative coupling (CDC) of aldehydes with N-hydroxyimides by visible light photoredox catalysis

A safer route for preparation of anion exchange membrane from inter-polymer film and performance evaluation in electrodialytic application

Oxidative esterification of benzylic alcohols with a catalytic amount of HBr-H2O2 in aqueous medium under mild conditions is reported with a wide range of substrate scope for both benzylic and aliphatic alcohols. The conditions are also suitable for selective mono-esterification of ethylene glycol and glycerol. With catalytic amounts of HBr (20 mol%) and H2O2, the generation of reactive intermediate species BrOH has been ascertained by UV-visible spectra.

Transition metal-free oxidative esterification of benzylic alcohols in aqueous medium

Upgraded bio-oil derived from the thermochemical conversion of biomass has the potential to replace liquid fossil fuels. In this work we report the generation of high energy density oil via the slow fixed-bed pyrolysis of Jatropha curcas shells and the subsequent upgradation of the crude bio-oil by means of a simple organic reaction. The optimization for maximum productivity of the bio-oil was carried out at temperatures of 300, 400, 500, and 600 °C. Kinetic study indicated the favorable heating rate to be 5 °C min–1. The maximum bio-oil, with a yield of 31.14%, was obtained at 400 °C with a holding time of 4 h. The bio-oil, containing ca. 40% carbonyl (>C═O) derivatives, was converted into the corresponding methylene (−CH2−) derivative by treatment with hydrazine hydrate/sodium hydroxide. The resultant oil, containing mostly ethylbenzene, had a high calorific value and thus might be suitable to replace fossil diesel or gasoline. The bio-chars obtained at the specific carbonization temperatures were also ...

High Energy Density Bio-oil via Slow Pyrolysis of Jatropha curcas Shells

Iodine catalyzed synthesis of 2,5-disubstituted oxazoles from N-arylethylamides through intramolecular C(sp3)–H functionalization under metal-free conditions is described. The method is tolerable to a wide range of substrates having a variety of functional groups with moderate to good yields of the products.

Milan Dinda

Papers

Cross dehydrogenative coupling (CDC) of aldehydes with N-hydroxyimides by visible light photoredox catalysis

A safer route for preparation of anion exchange membrane from inter-polymer film and performance evaluation in electrodialytic application

Transition metal-free oxidative esterification of benzylic alcohols in aqueous medium

High Energy Density Bio-oil via Slow Pyrolysis of Jatropha curcas Shells

Iodine catalysed intramolecular C(sp3)–H functionalization: synthesis of 2,5-disubstituted oxazoles from N-arylethylamides