Parameters Affecting the Fuel Cell Reactions on Platinum Bimetallic Nanostructures

In this paper the electrochemical properties of some platinum-based nanoalloys are reviewed. The revision is centered on electrocatalytic materials generated via the carbonyl chemical route (CCR). In considering the effects of segregation in these bimetals, the reaction of the hydrogen oxidation (HOR) and oxygen reduction (ORR) in the alkaline medium was investigated. The reaction kinetics of these electrochemical processes in the alkaline electrolyte is still a challenge. For the design of high-performance platinum-based electrocatalysts, it is of importance to know that the kinetics of HOR and ORR also depends on the Pt adsorbate. The electrochemical analysis, based on the study of Pt nanoalloyed surfaces with different Pt-adsorbate interactions, was taken into account. A clear trend in the HOR as well as the ORR activity, in the alkaline electrolyte, was established, revealing that the activity changes in the order PtSn/C < PtCr/C < Pt/C (JM) < PtCo/C < PtNi/C for the former, and for the latter Pt/C (Tek) < Pt/C (JM) < PtCr/C < PtNi/C. The decisive effect of the Pt-H-ad energy on the HOR kinetics on Pt surfaces apparently depends on the oxophilicity role of the metal to favor M-OHad. The apparent electronic effect is not evident on these materials, except if a strong metal interaction is induced per se with either the carbon or oxide supports, e.g., the Pt/SnO2-C interface in acidic media. Favorable effects of Pt-H-ad energy on HOR kinetics were found with the oxophilicity of the sp(2) domains of carbon that serve as anchoring or nucleation sites for platinum atoms. These results were compared with the literature data, and it turns out that this type of strong metal support interaction (SMSI) modification is favorably induced by UV-VIS irradiation and outperforms Pt-M materials to some extent. Either for HOR or ORR, it is shown that non-noble metals not only act as a surrogate metal for Pt utilization by inducing a compressive stress effect between the Pt atoms in the outermost layer but also participate in the electrocatalytic reaction. This information is important to understand and develop structures with the Pt/C catalyst for the manufacture of electrode materials in the alkaline medium.