Cells F 3000Stabilization of Platinum Oxygen-Reduction Electrocatalysts Using Gold Clusters. -Pt oxygen-reduction fuel cell electrocatalysts are stabilized against dissolution under potential cycling regimes (a continuing problem in vehicle applications) by modifying Pt nanoparticles with Au clusters. There are insignificant changes in the activity and surface area of Au-modified Pt under the oxidizing conditions of the O2 reduction reaction and potential cycling between 0.6 and 1.2 V in over 30,000 cycles, in contrast to sizable losses with the pure Pt catalyst under the same conditions. In situ XANES and voltammetry data suggest that the Au clusters confer stability by raising the Pt oxidation potential. -(ZHANG, J.; SASAKI, K.; SUTTER, E.; ADZIC, R. R.; Sci.

The presence of hydroquinone (HQ), a phenol, ubiquitous in nature and widely used in industry needs to be monitored due to its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast and non-invasive electrochemical measurements on ITO electrodes modified with nanoparticles comprising bimetallic Au-In cores and mixed Au-In oxide shells. While bare ITO electrodes show very low activity for the detection of HQ, their modification with Au-In core-shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated with the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au-In oxide shells available for the electrochemical reaction. While adding core-shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone-hydroquinone couple, which gives rise to high oxidation peaks, and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au-In oxide shells. The LODs were in the range of 10-5-10-6 M and were lower than those obtained using bulk Au.

Correction for ‘Alloy oxidation as a route to chemically active nanocomposites of gold atoms in a reducible oxide matrix’ by P. Sutter et al., Nanoscale Horiz., 2016, 1, 212–219.