Fuel Cell technology has emerged as a fully employable technological tool that could help decrease our current fossil fuel dependence while also lowering harmful gas emissions. For this purpose, platinum has been the benchmark catalyst for oxidation of hydrogen and simple alcohols relying on its high activity at relatively low overpotentials, however it is severely poisoned by chemisorption of intermediate species. Gold (Au) lacks the activity of Pt in proton exchange membrane applications in acidic media, however in alkaline media Au has been tested to be extremely active for alcohol oxidation when its size goes into the nanometer range. Therefore, the Au NP’s synthetic procedure is key in obtaining and sustaining high alcohol oxidation efficiencies. This work focuses on an electrosynthetic procedure to obtain Au NPs deposited on a carbon substrate using a technique called Rotating Disk Slurry Electrodeposition (RoDSE) to further use it as a catalyst for ethanol electrooxidation in alkaline media. Traditional synthesis methods which require a reducing agent and a surfactant are replaced by applying a constant reduction voltage and the agglomeration is tuned by RDE rotations. We also showed that electrolyte media greatly influenced the morphological features of the as deposited catalysts confirmed by Transmission Electron Microscopy (TEM) and surface area analysis using the associated cathodic Au-OH stripping peak in KOH. We reported a 10X increase in electroactive surface area (EAS) when conducting the electrosynthesis in alkaline media compared to neutral and acidic media electrodepositions although the metal precious loading was approximately 10% confirmed by TGA and ICP for all the catalysts. Finally, our synthesized catalysts were compared to the traditional synthesis using a reducing agent to obtain 10% Au sphere nanoparticles for ethanol electrooxidation using cyclic voltammetry and chronoamperometry showing superior activity and stability in the RoDSE materials at similar precious metal loadings (10%). Therefore, the functionalities imparted by the electrolyte media and the rotations of the electrode were key in creating optimal nucleation sites in the support (Vulcan XC-72R) to attach highly dispersed Au NPs.<br/>

Synthesis and characterization of highly active Au NPs using the rotating disk slurry electrodepoition technique for EtOH electrooxidation in alkaline media

253rd National Meeting (2017)

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