Alkaline Anion-Exchange Membrane Fuel Cells: Challenges in Electrocatalysis and Interfacial Charge Transfer.

Alkaline anion-exchange membrane (AAEM) fuel cells have attracted significant interest in the past decade, thanks to the recent developments in hydroxide-anion conductive membranes. In this article, we compare the performance of current state of the art AAEM fuel cells to proton-exchange membrane (PEM) fuel cells and elucidate the sources of various overpotentials. While the continued development of highly conductive and thermally stable anion-exchange membranes is unambiguously a principal requirement, we attempt to put the focus on the challenges in electrocatalysis and interfacial charge transfer at an alkaline electrode/electrolyte interface.

Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal-nitrogen coordination.

Replacement of noble metals in catalysts for cathodic oxygen reduction reaction with transition metals mostly create active sites based on a composite of nitrogen-coordinated transition metal in close concert with non-nitrogen-coordinated carbon-embedded metal atom clusters. Here we report a non-platinum group metal electrocatalyst with an active site devoid of any direct nitrogen coordination to iron that outperforms the benchmark platinum-based catalyst in alkaline media and is comparable to its best contemporaries in acidic media. In situ X-ray absorption spectroscopy in conjunction with ex situ microscopy clearly shows nitrided carbon fibres with embedded iron particles that are not directly involved in the oxygen reduction pathway.

Elucidating Oxygen Reduction Active Sites in Pyrolyzed Metal-Nitrogen Coordinated Non-Precious-Metal Electrocatalyst Systems.

Detailed understanding of the nature of the active centers in non-precious-metal-based electrocatalyst, and their role in oxygen reduction reaction (ORR) mechanistic pathways will have a profound effect on successful commercialization of emission-free energy devices such as fuel cells. Recently, using pyrolyzed model structures of iron porphyrins, we have demonstrated that a covalent integration of the Fe-N sites into π-conjugated carbon basal plane modifies electron donating/withdrawing capability of the carbonaceous ligand, consequently improving ORR activity. Here, we employ a combination of X-ray spectroscopy and electrochemical methods to identify the various structural and functional forms of the active centers in non-heme Fe/N/C catalysts.

Activity descriptor identification for oxygen reduction on nonprecious electrocatalysts: linking surface science to coordination chemistry.

Developing nonprecious group metal based electrocatalysts for oxygen reduction is crucial for the commercial success of environmentally friendly energy conversion devices such as fuel cells and metal-air batteries. Despite recent progress, elegant bottom-up synthesis of nonprecious electrocatalysts (typically Fe-N(x)/C) is unavailable due to lack of fundamental understanding of molecular governing factors. Here, we elucidate the mechanistic origin of oxygen reduction on pyrolyzed nonprecious catalysts and identify an activity descriptor based on principles of surface science and coordination chemistry.

Neuroprotective effects of a new synthetic peptide, CMX-9236, in in vitro and in vivo models of cerebral ischemia.

NGF (nerve growth factor) and BDNF (brain-derived neurotrophic factor) are protein molecules (MW 26 and 13.6 kDa, respectively) that are neuroprotective in the middle cerebral artery occlusion (MCAO) rat stroke model. Their mechanism of action involves the activation of transcription factor AP-1 that turns on neuronal growth genes.

CMX-8933, a peptide fragment of the glycoprotein ependymin, promotes activation of AP-1 transcription factor in mouse neuroblastoma and rat cortical cell cultures.

An 8-amino acid peptide fragment (CMX-8933) of Ependymin, a glycoprotein component of the extracellular fluid and cerebrospinal fluid of goldfish brain, was synthesized and tested for its capacity to activate AP-1 transcription factor in cell cultures. Dose-response and time-course studies of AP-1's binding to DNA were carried out in neuroblastoma (NB2a/dl) and primary rat brain cortical cultures using an electrophoretic mobility shift assay (EMSA). A 13-14-fold increase in AP-1's DNA binding was obtained when NB2a cells were incubated for 4 h with 6-10 microg/ml CMX-8933.