Following adoption and implementation of stringent laws governing sustainability and environmental impact of various energy generation systems, low-temperature fuel cells have attracted much research attention. These cells have gained popularity particularly due to their low operating temperatures, lower carbon emission and higher energy efficiency. Many types of fuel cells have been devised, but of concern here are direct methanol-based fuel cells owing to their applicability in mobile systems. So far, the main issue with the direct methanol fuel cells (DMFCs) is the incomplete reduction of methanol on platinum (Pt) that leads to the absorption of CO-like intermediates, which in turn dramatically impede the kinetics of methanol oxidation on platinum.
To counteract this drawback, various approaches have been developed; where utilization of metal oxides has carried the day based on economics and relative efficiency. In particular, iron oxide has been shown to change the platinum electronic structure and also improve its electrocatalytic properties. Moreover, interesting observation have been reported with the hematite material, thus further exploration would be highly welcome.
To this effect, McGill University scientists: Zishuai Zhang, Dr. Edward J. Harvey, Minnan Ye and Dr Geraldine Merle investigated the electrocatalytic performance of platinum hematene binary composites for MOR in alkaline environments. Their work was motivated by the notion that from an application point of view, combining platinum with hematene would lead to the development of an ideal anodic material for a direct-methanol fuel cell. Their work is currently published in Journal of The Electrochemical Society.
In brief, the research team successfully synthesized platinum-hematene sheets by ultrasonic exfoliation followed by a double pulse deposition strategy to adjust the platinum loading. Next, the morphology, structure, and composition of the new class of platinum decorated metal oxide nanosheet was characterized by transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. Lastly, electrocatalytic characteristics were systematically investigated by cyclic voltammetry and compared with commercial Pt/C catalyst.
The authors reported that the catalysts showed a comparable activity for methanol oxidation but most of all, a CO tolerance three times higher than conventional Pt/C catalyst. Additionally, they were able to relate the high tolerance to CO to the platinum’s nanoparticle size and its uniform distribution on the stable hematene nanosheet support.
In a nutshell, the study led by Dr. Merle at McGill University reported a systematic approach through which a 3-atom-thick hematene sheet was used for the first time as a novel class of catalytic support on which platinum nanoparticles were uniformly deposited. The presented approach employed a well-established double pulse electrodeposition to precisely control morphology, size, density and loading of platinum on hematene. Overall, the findings of McGill University researchers open new avenues for 2D hematene as promising electrocatalytic support for practical use in fuel cells.
Zishuai Zhang, Minnan Ye, Edward J. Harvey, Geraldine Merle. Methanol Electrooxidation with Platinum Decorated Hematene Nanosheet. Journal of The Electrochemical Society, volume 166 (4) page H135-H139 (2019).Go To Journal of The Electrochemical Society