This work revises the essentials of electrocatalytic electrochemical measurement done in alkaline electrolytes. The hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR) were considered as a baseline to understand some key critical factors in a half-cell system. The material considered herein was essentially the carbon supported platinum nanoparticles as benchmark material. The main electrochemical techniques considered were cyclic voltammetry (CV) and the rotating disk electrode (RDE). The critical factors considered were the electrochemical cell vessel, reference electrode, nature of the cation in the alkaline electrolyte, and ohmic drop correction. The anion-exchange membrane as electrolyte for alkaline fuel cells (AFCs) provides opportunities to develop non-precious metal (NPM) catalytic centers. This is certainly an advantage that AFC can offer to activate NPM toward the cathodic oxygen reduction reaction (ORR), with a performance approaching that of platinum (Pt). Nonetheless, in such an alkaline medium the hydrogen oxidation reaction (HOR) is challenging, even for platinum that shows a sluggish kinetics and regardless of the fact the mechanism is still not well-understood.2 Numerous efforts to tailor high active and stable nanostructured electrocatalyst (including precious and non-precious centers) for AFCs have been performed. Moreover, important experimental issues have not yet being normalized. This is essential, in order to compare data generated in various laboratories. A series of experimental questions, such as, ink formulation, thin-film coated quality, catalyst loading, electrochemical cell, reference electrode, temperature, electrolyte cation and so on, can indeed affect considerably the electrochemical measurements. One can, moreover, find in the literature excellent protocols to normalize fuel cell electrocatalytic reactions in acid measurements, 3-7 using commercial Pt/C as benchmark material. Protocols for the alkaline medium are seldom, however, a recent work analyses the impact of impurities in alkaline electrolytes. 8 Moreover, to the best of our knowledge, the reported data to obtain reproducible and comparable results in alkaline media are still lacking, since different experimental protocols used for the evaluation of, e.g., benchmark Pt/C in alkaline medium, make it difficult to compare the HOR, and ORR kinetics. Reproducibility and replicability in the measurements is of paramount importance in order to assess good performance of advanced electrocatalytic materials. This work provides a protocol to perform, as a baseline, the HOR and ORR processes, generated on carbon supported platinum NPs in alkaline electrolyte.
An Overview on Alkaline HOR and ORR Data in the Last DecadeThe research on fuel cell reactions (HOR and ORR) in alkaline medium reflects the principal development of the proton-exchange membrane fuel cells (PEMFC). The former approach is more focused on novel NPM catalytic centers. Commercial-based platinum electrocatalytic material in massif, single cr...