The mass diffusion overpotential distribution in a free-breathing proton exchange membrane fuel cell (PEMFC) was determined from current distribution measurements using a flow pulse approach. The current distribution measurements were conducted with a segmented flow-field plate. Flow pulses were fed to the cathode channels to form a uniform oxygen concentration distribution along the channels. ...

We quantitatively characterized oxygen reduction kinetics at the nanoscale Ptmid R:CsHSO(4) interface at approximately 150 degrees C in humidified air using conducting atomic force microscopy (AFM) in conjunction with AC impedance spectroscopy and cyclic voltammetry. From the impedance measurements, oxygen reduction at Ptmid R:CsHSO(4) was found to comprise two processes, one displaying an expo...

Improved electrocatalysts for the oxygen reduction reaction (ORR) are critical for the advancement of fuel cell technologies. Herein, we report a series of 11 soluble iron porphyrin ORR electrocatalysts that possess turnover frequencies (TOFs) from 3 s-1 to an unprecedented value of 2.2 × 106 s-1. These TOFs correlate with the ORR overpotential, which can be modulated by changing the E1/2 of th...

Diaphorase catalyzes efficiently the oxidation of NADH to NAD+ by benzylviologen. This reaction was used to regenerate the NADf required for the biocatalyzed oxidation of methanol to CO, using NADf-dependent dehydrogenases. A rnethanol/dioxygen biofuel cell was assembled using these bioreactions in the anode compartment. The open-circuit voltage of the cell was 0.8 V, and the maximum power outp...

Linear trimetallic Co(III)/Co(II)/Co(III) cobalt complexes with bridging acyl-alkoxy ligands are electrocatalysts for the reduction of tosic acid in acetonitrile. The -OCMe2CH2COMe complex appears to operate homogeneously, and at a modest onset overpotential of 175 mV. A turnover frequency of ca. 80 s(-1) was observed at an overpotential of 300 mV.

Dual redox mediators (RMs) were introduced for Mg-O2 batteries. 1,4-Benzoquinone (BQ) facilitates the discharge with an overpotential reduction of 0.3 V. 5,10,15,20-Tetraphenyl-21H,23H-porphine cobalt(ii) (Co(ii)TPP) facilitates the recharge with an overpotential decrease of up to 0.3 V. Importantly, the two redox mediators are compatible in the same DMSO-based electrolyte.

Polymer electrolyte membrane fuel cells (PEMFC) fed with H2 contaminated with CO may exhibit oscillatory behavior when operated galvanostatically. The self-organization of the anodic overpotential is interesting because it can be accompanied by an increase in the average performance. Herein we report experimental studies of voltage oscillations that emerge in a PEMFC equipped with a Pd/C or PdP...

The compound CsH2PO4 has emerged as a viable electrolyte for intermediate temperature (200-300 degrees C) fuel cells. In order to settle the question of the high temperature behavior of this material, conductivity measurements were performed by two-point AC impedance spectroscopy under humidified conditions (p[H2O] = 0.4 atm). A transition to a stable, high conductivity phase was observed at 23...

In this paper, the electro-thermal model of Lithium-ion battery for electric vehicles and its related application were studied. The spatial variations of electrode parameter and the reaction heat generated inside battery must be considered when developing an electro-thermal model of Lithium-ion battery for electric vehicles, to ensure the applicability of the developed model under different ope...