The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

http://repository.ust.hk/ir/bitstream/1783.1-77094/1/acs.chemrev.5b00462_withlink.pdf

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

More than 95% (in volume) of all of today’s chemical products are manufactured through catalytic processes, making research into more efficient catalytic materials a thrilling and very dynamic rese...

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

Molecularly imprinted polymers are synthetic receptors for a targeted molecule. As such, they are analogues of the natural antibody–antigen systems. In this review, after a recounting of the early history of the general field, we specifically focus on the application of these polymers as sensors. In these applications, the polymers are paired with a reporting system, which may be electrical, electrochemical, optical, or gravimetric. The presence of the targeted molecule effects a change in the reporting agent, and a calibrated quantity of the target is recorded. In this review, we describe the imprinted polymer production processes, the techniques used for reporting, and the applications of the reported sensors. A brief survey of recent applications to gas-phase sensing is included, but the focus is primarily on the development of sensors for targets in solution. Included among the applications are those designed to detect toxic chemicals, toxins in foods, drugs, explosives, and pathogens. The application...

Molecularly Imprinted Polymers

A comprehensive review of recent advances in the field of oxygen reduction electrocatalysis utilizing nonprecious metal (NPM) catalysts is presented Progress in the synthesis and characterization of pyrolyzed catalysts, based primarily on the transition metals Fe and Co with sources of N and C, is summarized Several synthetic strategies to improve the catalytic activity for the oxygen reduction reaction (ORR) are highlighted Recent work to explain the active-site structures and the ORR mechanism on pyrolyzed NPM catalysts is discussed Additionally, the recent application of Cu-based catalysts for the ORR is reviewed Suggestions and direction for future research to develop and understand NPM catalysts with enhanced ORR activity are provided

Nonprecious Metal Catalysts for Oxygen Reduction in Heterogeneous Aqueous Systems

Abstract Electrochemical surface oxidation of carbon black Vulcan XC-72 and multiwalled carbon nanotube (MWNT) has been compared following potentiostatic treatments up to 168 h under condition simulating PEMFC cathode environment (60 °C, N2 purged 0.5 M H2SO4, and a constant potential of 0.9 V). The subsequent electrochemical characterization at different treatment time intervals suggests that MWNT is electrochemically more stable than Vulcan XC-72 with less surface oxide formation and 30% lower corrosion current under the investigated condition. As a result of high corrosion resistance, MWNT shows lower loss of Pt surface area and oxygen reduction reaction activity when used as fuel cell catalyst support.

http://ma.ecsdl.org/content/MA2005-02/33/1168.full.pdf

Durability Investigation of Carbon Nanotube as Catalyst Support for Proton Exchange Membrane Fuel Cell Electrode

Inspired by copper-based oxygen reduction biocatalysts, we have studied the electrocatalytic behavior of a Cu-based MOF (Cu-BTT) for oxygen reduction reaction (ORR) in alkaline medium. This catalyst reduces the oxygen at the onset (Eonset ) and half-wave potential (E1/2 ) of 0. 940 V and 0.778 V, respectively. The high halfway potential supports the good activity of Cu-BTT MOF. The high ORR catalytic activity can be interpreted by the presence of nitrogen-rich ligand (tetrazole) and the generation of nascent copper(I) during the reaction. In addition to the excellent activity, Cu-BTT MOF showed exceptional stability too, which was confirmed through chronoamperometry study, where current was unchanged up to 12 h. Further, the 4-electrons transfer of ORR kinetics was confirmed by hydrodynamic voltammetry. The oxygen active center namely copper(I) generation during ORR has been understood by the reduction peak in cyclic voltammetry as well in the XPS analysis.

Sodalite-type Cu-based Three-dimensional Metal-Organic Framework for Efficient Oxygen Reduction Reaction.

Energy-Dense Aqueous Carbon/Carbon Supercapacitor with a Wide Voltage Window

Synthesizing an active and stable oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalyst in cost effective way remains a challenge in fuel cells and rechargeable metal-

Nickel-Based Hybrid Material for Electrochemical Oxygen Redox Reactions in an Alkaline Medium

Abstract This study reports a synthesis of carbon supported graphitic carbon nitride (g-C3N4-KBC) obtained by pyrolysis of melamine with Ketjenblack 600JD carbon (KBC) at 550°C for 4 h in a N2 atmosphere. g-C3N4-KBC oxidizes hydrazine at an onset potential 0.145 V vs. SCE close to the thermodynamic standard potential of hydrazine (0.23 V vs. SHE). In comparison to the controls, KBC and g-C3N4, g-C3N4-KBC oxidizes hydrazine at lower overpotential.Most research has tended to focus on transition metal-based catalysts and few are of carbon material such as graphene nanoflakes, graphene oxide, and carbon nanotubes. A comparison in terms of sensitivity, detection range and stability reveals g-C3N4-KBC electrode’s superiority over other carbon material-based catalysts. To the best of our knowledge, the g-C3N4-KBC catalyst is not reported for sensing hydrazine in the literature.

Kothandaraman Ramanujam

Papers

Sodalite-type Cu-based Three-dimensional Metal-Organic Framework for Efficient Oxygen Reduction Reaction.

Energy-Dense Aqueous Carbon/Carbon Supercapacitor with a Wide Voltage Window

Nickel-Based Hybrid Material for Electrochemical Oxygen Redox Reactions in an Alkaline Medium

Carbon supported g-C3N4 for electrochemical sensing of hydrazine

Confinement Catalysis of Non-covalently Functionalized Carbon Nanotube in Ascorbic Acid Sensing