Abstract
The effect of the nature of the catalyst on the performance and mechanism of the hydrogen oxidation reaction (HOR) is discussed for the first time in this work. HOR is an anodic reaction that takes place in anionic exchange membrane fuel cells (AEMFCs) and hydrogen pumps (HPs). Among the investigated catalysts, Pt exhibited the best performance in the HOR. However, the cost and the availability limit the usage. Co is incorporated as a co-catalyst due to its oxophylic nature. Five different PtCo catalysts with different Pt loading values were synthesized in order to decrease Pt loading. The catalytic activities and the reaction mechanism were studied via electrochemical techniques, and it was found that both features are a function of Pt loading; low-Pt-loading catalysts (Pt loading < 2.7%) led to a high half-wave potential in the hydrogen oxidation reaction, which is related to higher activation energy and an intermediate Tafel slope value, related to a mixed HOR mechanism. However, catalysts with moderate Pt loading (Pt loading > 3.1%) exhibited lower E1/2 than the other catalysts and exhibited a mechanism similar to that of commercial Pt catalysts. Our results demonstrate that Co plays an active role in the HOR, facilitating Hads desorption, which is the rate-determining step (RDS) in the mechanism of the HOR.
Highlights
Co/MWCNT exhibited two diffracted intensity peaks, at 26.4◦ (002) and 43.1◦ (100), that indexed to the structure of graphite reflections (JCPDS card No 96-120-0018), which have a decrease in the crystallinity order of MWCNTs due to functionalization treatment
The performance and mechanism of the hydrogen oxidation reaction (HOR) for PtCo/MWCNT catalysts were studied in order to optimize the Pt loading on the catalyst
The catalyst with the minimum Pt loading (PtCo/MWCNT 1, Pt loading around 0.4%) did not exhibit a response toward the HOR or the Co/MWCNT template
Summary
The main strategy for the energy policies around the world consists in the incorporation of clean electrical energy from renewable resources in the electrical energy network. The generation rate from renewable resources is relatively unpredictable, depending upon several factors, such as the season, the weather, orography, and the availability of the resource (tidal, wind, solar, chemical, etc.) [1,2]. Of renewable energy to an electrical grid is a difficult task, since the generation/conversion rate does not usually match the requirements of the grid. In this regard, storage of the surplus electricity is important for the management of electrical energy supply.
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