Vulcan Xc-72R Supported Silver-Based Bimetallic Nanoparticles As Novel Electrocatalytic Platforms for Improve Performance in Oxygen Reduction Reactions
Authors: Vega Melissa 
Published: February 2020

The Oxygen Reduction Reaction (ORR) is an essential process for energy transformation required by technological devices such as batteries and fuel cells.1,2 This reaction is responsible for controlling the activity and the activity of such devices suffers from a slow kinetic drawback at the cathode which hinders its overall performance.3 Thus, to accelerate ORR kinetics in a fuel cell, an active catalyst is required with qualities such as low cost and high catalytic stability.3 Platinum has proven to be the optimal catalyst for ORR but, due to its high cost and low abundance, adequate efforts have been made to be able to replace it.4 As of now, researchers have focused on silver metal because it is inexpensive and has proven to be a good catalyst for ORR in alkaline media.5 Hence, to improve the ORR in a fuel cell, we are depositing silver nanoparticles (NPs) onto electrochemically reduced vulcan XC-72R to achieve greater conductivity and surface area to the nanocomposite. Silver bimetallics have proven to be five times better in performance than pure silver in alkaline media. Thus, we will compare our Ag/GOx NPs with bimetallic NPs (Ag/Au) and (Ag/ Pd) at a 4:1 ratio to examine the catalytic activity for ORR. These nanocatalysts will be obtained directly using a robust electrodeposition method consisting of the rotating disk slurry electrode (RoDSE) technique in powder form, to obtain Ag nanoparticles highly dispersed on Vulcan XC-72R for ORR in alkaline media minimizing the time spent in catalyst preparation(fig 1). Afterwards, the sample’s electrochemical activity will be assessed for the ORR using both: cyclic voltammetry and spectroscopic analysis. The RoDSE method used to obtain highly dispersed Ag nanoparticles does not require the use of a reducing agent or stabilizing agent, and the noble-metal loading was controlled by the addition and tuning of the metal precursor concentration. This technique consists of dissolving a salt of the precursor metal in a carbon support to form the slurry solution in which a constant reducing potential is applied at a constant speed to achieve the electrodeposition of metal in the carbon support instead of the electrode.Particle size and characteristic of the bimetallic fcc crystal facets were determined by X-ray diffraction with an approximate size of 21.6, 18.8 and 19.8 nm for Ag, Ag/Au and Ag/Pd respectively. Cyclic voltammetry of electrodeposited 12 % Ag/Pd/Vulcan XC-72R showed a higher catalytic current density for oxygen reduction reaction when compared with the others bimetallic under study.

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Figure 1