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Alkaline-based fuel cells have garnered renewed interest for low temperature, moderate-power applications since they are amenable to non-precious metal catalysts. We report a new and efficient synthesis route to produce an active and stable catalyst for the oxygen reduction reaction (ORR) in alkaline environments. The catalyst consists of manganese oxide (MnOx) supported onto glassy carbon (GC) particles, which serve as a support material that is more resistant to heat and corrosion than conventional high surface area carbon supports. Impregnation of the MnOx onto the GC particles followed by high-temperature calcination generates a catalytically active Mn3O4 surface with a nanostructured morphology. The MnOx-GC particles display high activity for the ORR in an alkaline electrolyte, comparable to that of best-known non-precious metal catalysts and within 0.15 V of a commercial Pt catalyst. Accelerated durability testing reveals excellent stability of the MnOx-GC catalyst, maintaining nearly 60% of its activity after 30,000 cyclic voltammograms. The catalyst was integrated into the cathode of an alkaline exchange membrane fuel cell (AEMFC) with Pt at the anode, achieving a peak power density of 98 mW/cm² at 70°C, demonstrating the viability of the MnOx-GC catalyst in a device environment. [ABSTRACT FROM AUTHOR]

Abstract: Au/α-Fe2O3 was combined with a CO2-sorbent (3-aminopropyltriethoxysilane (APTES) grafted on SBA-15 and hereafter denoted as APTES/SBA-15) to enhance preferential oxidation (PROX) of CO in H2. The CO2 molecules could be rapidly adsorbed on APTES/SBA-15 at low temperatures below 50 °C with a capacity of 0.68 mmol CO2/g-sample, and desorbed at a temperature range of 50 °C–80 °C. Three different configurations of the Au/α-Fe2O3 catalyst and the CO2-sorbent were tested in the PROX reaction, namely (i) the sorbent-free (catalyst//SBA-15//catalyst) configuration, (ii) the packed three-layer configuration (catalyst//CO2-sorbent//catalyst), and (iii) the mechanically mixed catalyst and CO2-sorbent configuration. Compared to configuration (i), configuration (ii) achieved an average 10% higher CO conversion at 50 °C and a GHSV of 65000 h−1. However, the CO concentration could not be lowered to below 70 ppm from 2000 ppm using configuration (ii) at a GHSV of 10000 h−1. Thus, a 5-layer configuration (catalyst//CO2-sorbent//catalyst//CO2-sorbent//catalyst) was used, and the CO concentration was lowered to ca. 25 ppm. The mechanism for enhancement of the PROX reaction by the continuous removal of CO2 by the CO2-sorbent is discussed and attributed to reduction of the surface carbonate on the Au/α-Fe2O3 catalyst formed during the PROX process. [ABSTRACT FROM AUTHOR]