Assessment of the Reproducibility of Experimental Results in Aqueous Alkaline Media Using Pt Electrodes

Research in interfacial electrochemistry and electrocatalysis requires establishing standard experimental procedures and conditions that ensure reproducibility and reliability of results. While standard procedures for experimental research employing Pt electrodes in aqueous acidic solutions were established ca. 50 years ago, similar benchmarks for aqueous alkaline media do not exist. In this contribution, cyclic voltammetry (CV) experiments are performed in the 0.05–1.40 V range using polycrystalline and monocrystalline platinum electrodes (Pt(poly) and Pt(POSSC)) in 0.50 M aqueous H2SO4 (a reference electrolyte solution) and 0.10 M aqueous NaOH (a studied electrolyte solution) to verify the systems’ cleanliness and to determine the electrodes’ electrochemically active surface area (Aecsa). Afterward, chronoamperometry (CA) measurements are conducted by holding the applied potential at 0.50 V for various holding times in the 30–1,800 s range, and then Aecsa is re-evaluated by CV experiments. The results demonstrate that unavoidable contamination, present even in the highest purity chemicals and water, adsorbs on the surface of the Pt electrodes and reduces their Aecsa. The reduction in Aecsa increases with increasing the holding time in CA measurements. Energy-dispersive X-ray (EDS) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses of the Pt(poly) and Pt(POSSC) electrodes reveal the presence of C and O-containing compounds in the case of aqueous H2SO4 solution and C, O, and Pb compounds in the case of aqueous NaOH solution. The results demonstrate the complementarity of electrochemical and surface science methods in assessing the cleanliness of electrode materials and highlight the need for rigorous experimental protocols that ensure reproducibility and reliability of experimental results.