Electrochemical activity of several compositions in the system Ag-Pd-Pt-Ru for the oxygen reduction reaction in 0.05 M KOH solution pH 12.5

The dataset comprises electrochemical screening data of several compositions from three different thin film materials libraries in the system Ag-Pd-Pt-Ru. Given are three csv files that contain the measurement coordinates, the chemical composition in atomic percent and the electrochemical current that was evaluated from linear sweep voltammograms at a potential of 0.85V vs. RHE. 

Experimental description

Materials libraries were fabricated by co-sputtering thin films on 100 mm diameter sapphire wafers (c-plane) from 4 elemental tar-gets. The targets were confocally aligned to a 100 mm substrate (target-substrate distance approx. 12 cm). Target materials had a purity of 99.99,%. Ar (99.9999 %) was used as a sputter gas. The deposition pressure was 0.667 Pa. The film thickness was 100 - 150 nm. The chemical composition of the materials libraries was measured by energy dispersive X-ray spectroscopy (EDX) with an acceleration voltage of 20 kV. 81 measurements were done on a regular grid of 9x9 (8.5 mm spacing) on each library. Linear regression was used to interpolate the composition over the 342 measurement areas of a 4.5 mm grid that was used in the scanning droplet cell experiments. Electrochemical measurements were conducted with the use of a high-throughput scanning droplet cell (SDC). The SDC head incorporates counter (Pt wire) and reference (Ag|AgCl|3 M KCl) electrodes and a teflon tip with 1 mm diameter. The materials library is connected as working electrode, e.g. the surface of the investigated sample in every spot where the tip touches the sample. The electrolyte was replaced for every measurement area. Linear sweep voltammograms were measured in 0.05 M KOH, pH 12.5, with a scan rate of 10 mV/s. All potentials are reported versus the RHE according to the following equation: URHE (V) = U(Ag|AgCl|3 M KCl) + 0.210 + (0.059 * pH), where U(Ag|AgCl|3 M KCl) is the potential measured versus Ag|AgCl|3 M KCl reference electrode, 0.210 V is the standard potential of the Ag|AgCl|3 M KCl reference electrode at 25◦C. Note that 0.059 is the result of (RT )· (nF)−1, where R is the gas constant, T is the temperature (298 K), F is the Faraday constant, and n is the number of electrons transferred during the reaction.